WO2014208356A1 - Optical film and light emitting device - Google Patents

Abstract

The objective of the present invention is to provide: an optical film which has excellent transparency and is provided with durability that enables suppression of deterioration of semiconductor nanoparticles for a long period of time, said deterioration being caused by oxygen or the like; and a light emitting device which is provided with this optical film. An optical film according to the present invention comprises a base and a semiconductor nanoparticle layer that is provided on the base. This optical film is characterized in that the semiconductor nanoparticle layer contains semiconductor nanoparticles, each of which is covered with a resin, and a polysilazane or modified polysilazane, in which the semiconductor nanoparticles are dispersed and held.

Description

Optical film and light emitting device

The present invention relates to an optical film and a light emitting device. In particular, the present invention relates to an optical film having durability capable of suppressing deterioration of semiconductor nanoparticles due to oxygen or the like over a long period of time and excellent in transparency, and a light emitting device including the optical film.

In recent years, semiconductor nanoparticles have gained commercial interest due to their variable electronic properties. Semiconductor nanoparticles are, for example, biomarkers, solar power generation, catalysis, bioimaging, light emitting diodes (hereinafter abbreviated as LEDs), general spatial illumination, and electroluminescent displays. It is expected to be used in various fields.

For example, as a light emitting device using semiconductor nanoparticles, the amount of light incident on a liquid crystal display (hereinafter abbreviated as LCD) by irradiating the semiconductor nanoparticles with LED light to emit light. Has been proposed (see, for example, Patent Document 1).

Here, it is known that semiconductor nanoparticles deteriorate when they come into contact with oxygen, and various means for preventing the semiconductor nanoparticles from coming into contact with oxygen have been adopted. As such means, for example, a method of sealing semiconductor nanoparticles with a barrier film or a sealing material can be mentioned. In such a method, although oxygen blocking performance can be secured, sealing is performed in a nitrogen gas atmosphere. Manufacturing facilities are expensive and sophisticated, such as the need for stopping work, and are inferior in versatility.

On the other hand, a method for preventing the semiconductor nanoparticles from coming into contact with oxygen by coating the semiconductor nanoparticles themselves with silica or glass has been proposed (see, for example, Patent Document 2 and Patent Document 3).

In addition, a method of forming a semiconductor nanoparticle layer by dispersing semiconductor nanoparticles in an inorganic matrix has been proposed (for example, see Patent Document 4).

However, the conventional technique of covering the surface of the semiconductor nanoparticles with silica or glass, or the method of dispersing them in an inorganic matrix can obtain oxygen barrier performance, but the silica nanoparticles of the semiconductor nanoparticles are formed. By increasing the particle size, the dispersibility in the layer is lowered, the transparency is lowered, or the oxygen blocking performance is lowered due to the influence of the external environment, the brightness is deteriorated, etc. It was insufficient in terms of durability.

On the other hand, Patent Document 5 proposes a method of dispersing and holding semiconductor nanoparticles in a transparent resin layer. However, the method proposed here is insufficient in terms of durability, for example, the luminance is deteriorated due to a decrease in oxygen barrier performance due to the influence of the external environment.

JP 2011-202148 A International Publication No. 2007/034877 Special table 2013-505347 gazette JP 2009-263621 A International Publication No. 2012/132239

The present invention has been made in view of the above problems, and its solution is an optical film having durability that can prevent deterioration of semiconductor nanoparticles due to oxygen or the like over a long period of time and having excellent transparency. It is to provide a light emitting device including the optical film.

As a result of intensive studies in view of the above problems, the present inventor contains, as a semiconductor nanoparticle layer, at least one compound selected from polysilazane and a modified polysilazane and semiconductor nanoparticles coated with a resin. It has been found that an optical film having excellent durability capable of preventing the deterioration of semiconductor nanoparticles due to oxygen or the like over a long period of time and further excellent in transparency can be obtained by constituting the present invention.

That is, the above-mentioned problem of the present invention is solved by the following means.

1. An optical film having a substrate and a semiconductor nanoparticle layer provided on the substrate,
The optical film, wherein the semiconductor nanoparticle layer contains at least one selected from semiconductor nanoparticles coated with a resin, polysilazane and a polysilazane modified body that disperses and holds the semiconductor nanoparticles.

2. The semiconductor nanoparticle layer contains the polysilazane modified body, and the polysilazane modified body is formed by irradiating the polysilazane with vacuum ultraviolet rays, and at least one selected from silicon oxide, silicon nitride, and silicon oxynitride 2. The optical film according to item 1, which is a compound containing the optical film.

3. 3. The optical film according to item 1 or 2, wherein the semiconductor nanoparticles have a core-shell structure.

4. The optical film according to any one of Items 1 to 3, wherein the resin is an ultraviolet curable resin.

5. The optical film according to any one of items 1 to 3, wherein the resin is a water-soluble resin.

6. The semiconductor nanoparticle layer having two or more layers, wherein the two or more semiconductor nanoparticle layers contain semiconductor nanoparticles having different emission wavelengths, respectively. The optical film as described in any one of the above.

7. A light emitting device comprising the optical film according to any one of items 1 to 6.

By the above means of the present invention, an optical film having excellent luminous efficiency and excellent durability capable of suppressing deterioration of semiconductor nanoparticles due to oxygen or the like over a long period of time and having excellent transparency and the optical film are provided. The light emitting device can be provided.

In the structure defined in the present invention, the polysilazane and the polysilazane modified body, which are constituent elements of the present invention, not only have an oxygen-blocking property but also an oxygen-absorbing performance, so that it is possible to effectively reduce oxygen in contact with semiconductor nanoparticles. As a result, it is speculated that sufficient durability (oxidation resistance) can be secured. In addition, the polysilazane and the modified polysilazane can further improve the oxygen barrier property by light irradiation such as vacuum ultraviolet irradiation.

In the present invention, by incorporating semiconductor nanoparticles coated with a resin into the polysilazane or polysilazane modified body having the above properties, the semiconductor nanoparticles in the polysilazane or polysilazane modified body are contained. It is presumed that the optical film and the light-emitting device, which are greatly improved in dispersibility and excellent in transparency, luminous efficiency and durability, can be obtained.

Schematic sectional view showing an example of the configuration of the optical film of the present invention Schematic sectional drawing which shows an example of a structure of the light-emitting device which comprised the optical film containing the semiconductor nanoparticle of this invention

The optical film of the present invention is an optical film having a base material and a semiconductor nanoparticle layer provided on the base material, wherein the semiconductor nanoparticle layer is coated with a resin, It is characterized by containing at least one compound selected from polysilazane and a modified polysilazane as a binder for dispersing and holding semiconductor nanoparticles (hereinafter also referred to as “quantum dots”). This feature is a technical feature common to the inventions according to claims 1 to 7.

As an embodiment of the present invention, the semiconductor nanoparticle layer contains the polysilazane modified product, and the polysilazane modified product applies a vacuum ultraviolet ray to the polysilazane from the viewpoint of more manifesting the intended effect of the present invention. A compound containing at least one selected from silicon oxide, silicon nitride, and silicon oxynitride formed by irradiation is preferable from the viewpoint of obtaining higher-order oxygen barrier properties for semiconductor nanoparticles. .

In addition, the fact that the semiconductor nanoparticles have a core-shell structure can suppress the aggregation of the semiconductor nanoparticles, can further increase dispersibility, and can improve luminance efficiency. Good.

In addition, it is preferable that the resin is an ultraviolet curable resin from the viewpoint of easy manufacture of the optical film.

It is preferable that the resin is a water-soluble resin from the viewpoint that an optical film can be easily manufactured with simple manufacturing equipment.

Further, two or more semiconductor nanoparticle layers are provided, and the two or more semiconductor nanoparticle layers each contain semiconductor nanoparticles having different emission wavelengths, so that various optical emissions can be obtained as an optical film. It is preferable from a viewpoint which can be obtained.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the following description, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<Structure of optical film>
The optical film of the present invention comprises a base material, at least one compound selected from polysilazane and a modified polysilazane as a binder on the base material, and semiconductor nanoparticles whose particle surfaces are coated with a resin in the binder. It is characterized by having a semiconductor nanoparticle layer dispersed and contained.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the optical film of the present invention.

1, an optical film 11 of the present invention has a configuration in which a semiconductor nanoparticle layer 13 is laminated on a base material 12. The semiconductor nanoparticle layer 13 according to the present invention has a configuration in which the semiconductor nanoparticles 15 whose surfaces are coated with the resin 16 are dispersed in the polysilazane or polysilazane modified body 14 as a binder.

Hereinafter, details of each component constituting the optical film of the present invention will be described.

"Base material"
The base material applicable to the optical film of the present invention is not particularly limited as long as it has optical transparency, such as glass and plastic. Examples of the material preferably used as the base material having translucency include glass, quartz, and a resin film. Particularly preferred is a resin film from the viewpoint of imparting flexibility to the optical film.

The light transmittance of the substrate as used in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, more preferably 90% or more.

The thickness of the substrate is not particularly limited, but is generally in the range of 15 to 300 μm, preferably in the range of 15 to 200 μm, and more preferably in the range of 18 to 150 μm. .

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), and cellulose acetate. Cellulose esters such as phthalate and cellulose nitrate or derivatives thereof, polyethylene, polypropylene, cellophane, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, Polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, cyclone resins such as Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Etc.

Moreover, the gas barrier film | membrane which consists of an inorganic substance, an organic substance, or both may be formed in the surface of the said resin film. As such a gas barrier film, for example, a water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by a method according to JIS K 7129-1992 is 0.01 g. / (M ² · 24 h) or less is preferable, and the oxygen permeability measured by a method according to JIS K 7126-1987 is 1 × 10 ⁻³ ml / (m ² More preferably, it is a high gas barrier film having a water vapor permeability of 1 × 10 ⁻⁵ g / (m ² · 24 h) or less.

As a material for forming the gas barrier film, any material that has a function of suppressing intrusion of semiconductor nanoparticles such as moisture and oxygen may be used. For example, silicon oxide, silicon dioxide, silicon nitride, oxynitride Silicon or the like can be used. Furthermore, from the viewpoint of improving the brittleness of the gas barrier film, it is more preferable to have a laminated structure of these inorganic layers and organic layers made of organic materials. Although there is no restriction | limiting in particular about the lamination order of an inorganic layer and an organic layer, The structure which laminates | stacks two or more layers alternately is preferable.

The method for forming the gas barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is preferable.

《Semiconductor nanoparticle layer》
The semiconductor nanoparticle layer according to the present invention comprises at least one compound selected from polysilazane and a modified polysilazane and semiconductor nanoparticles coated with a resin. The optical film of the present invention is characterized by having at least one semiconductor nanoparticle layer according to the present invention, but the semiconductor nanoparticle layer may have a structure in which two or more layers are provided. . In the case of having two or more semiconductor nanoparticle layers, it is preferable that each semiconductor nanoparticle layer contains semiconductor nanoparticles having different emission wavelengths.

As one method for forming a semiconductor nanoparticle layer, a coating solution for forming a semiconductor nanoparticle layer containing a semiconductor nanoparticle coated with a polysilazane modified material and a resin is applied on a substrate, followed by drying treatment. The method of forming can be mentioned.

The coating method is not particularly limited, and a conventionally known wet coating method can be appropriately selected and applied. Specific wet methods include, for example, spin coating methods, roller coating methods, flow coating methods, ink jet methods, spray coating methods, printing methods, dip coating methods, cast film forming methods, bar coating methods, gravure printing methods, and the like. Is mentioned.

In addition, as a solvent that can be used when preparing a coating solution for forming a semiconductor nanoparticle layer, any solvent can be used as long as it does not react with semiconductor nanoparticles, polysilazane, modified polysilazane, and the like. It can be used even if it exists.

In addition, as another method for forming the semiconductor nanoparticle layer, after applying a semiconductor nanoparticle layer forming coating solution containing semiconductor nanoparticles coated with polysilazane and resin on a substrate, a method described later, for example, Alternatively, a method of forming a semiconductor nanoparticle layer by performing a modification treatment in which a part or all of polysilazane is modified into a polysilazane modified body by irradiation with excimer light or the like can also be used.

Further, the semiconductor nanoparticle layer preferably further contains a resin material, and more preferably contains an ultraviolet curable resin or a water-soluble resin. If the semiconductor nanoparticle layer contains an ultraviolet curable resin, that is, if the semiconductor nanoparticle layer forming coating solution contains an ultraviolet curable resin, apply the semiconductor nanoparticle layer forming coating solution. The coating layer thus formed is subjected to ultraviolet irradiation treatment. The ultraviolet irradiation treatment may also serve as a modification treatment for modifying the polysilazane described above. Details of the ultraviolet curable resin and the water-soluble resin will be described later.

The thickness of the semiconductor nanoparticle layer is not particularly limited, but is approximately in the range of 20 to 300 μm, preferably in the range of 50 to 200 μm, and more preferably in the range of 80 to 140 μm. is there.

<Semiconductor nanoparticles>
One feature of the semiconductor nanoparticle layer constituting the optical film of the present invention is that it contains semiconductor nanoparticles whose surface is coated with a resin. That is, the semiconductor nanoparticles are contained in the coating solution for forming the semiconductor nanoparticle layer.

The semiconductor nanoparticle according to the present invention refers to a particle having a predetermined size, which is composed of a crystal of a semiconductor material and has a quantum confinement effect, and whose particle diameter is in the range of several nanometers to several tens of nanometers. In this case, the quantum dot effect shown below is obtained.

Specifically, the particle diameter of the semiconductor nanoparticles according to the present invention is preferably in the range of 1 to 20 nm, more preferably in the range of 1 to 10 nm.

The energy level E of such semiconductor nanoparticles is generally expressed by the following formula (1) when the Planck constant is “h”, the effective mass of electrons is “m”, and the radius of the semiconductor nanoparticles is “R”. expressed.

Formula (1)
E∝h ² / mR ²
As shown by the formula (1), the energy level E (hereinafter also referred to as a band gap) of the semiconductor nanoparticles increases in proportion to the radius “R ⁻² ” of the semiconductor nanoparticles, so-called quantum dots. An effect is obtained. In this way, the band gap value of the semiconductor nanoparticles can be controlled by controlling and defining the particle diameter of the semiconductor nanoparticles. That is, by controlling and defining the particle diameter of the semiconductor nanoparticles, it is possible to impart diversity not found in ordinary atoms. Therefore, it can be excited by light, or converted into light having a desired wavelength and emitted. In the present invention, such a light-emitting semiconductor nanoparticle material is defined as “semiconductor nanoparticle” or quantum dot.

As described above, the average particle diameter of the semiconductor nanoparticles is in the range of several nanometers to several tens of nanometers, and is set to an average particle diameter corresponding to each target emission color. For example, when red light emission is desired, the average particle size of the semiconductor nanoparticles is preferably set within a range of 3.0 to 20 nm. When green light emission is desired, the average particle size of the semiconductor nanoparticles is selected. The diameter is preferably set in the range of 1.5 to 10 nm. When blue light emission is desired, the average particle diameter of the semiconductor nanoparticles is preferably set in the range of 1.0 to 3.0 nm. .

As a method for measuring the average particle diameter of the semiconductor nanoparticles according to the present invention, a known method can be used. For example, a method of observing semiconductor nanoparticles using a transmission electron microscope (TEM) and obtaining the number average particle size of the particle size distribution therefrom, or a method of obtaining an average particle size using an atomic force microscope (AFM) In addition, a particle size measuring apparatus using a dynamic light scattering method, for example, a method using a “Zeta Sizer Nano Series Zeta Sizer Nano ZS” manufactured by Malvern, Inc. can be used. In addition, there is a method of deriving the particle size distribution from the spectrum obtained by the X-ray small angle scattering method using the particle size distribution simulation calculation of the semiconductor nanoparticles. In the present invention, an atomic force microscope ( A method of obtaining an average particle size using AFM) is preferred.

In the semiconductor nanoparticles according to the present invention, the average aspect ratio (major axis diameter / minor axis diameter) value is preferably in the range of 1.0 to 2.0, more preferably 1.0. Is within the range of 1.7. The average aspect ratio (major axis diameter / minor axis diameter) of the semiconductor nanoparticles according to the present invention can be determined by measuring the major axis diameter and the minor axis diameter using, for example, an atomic force microscope (AFM). it can. The number of particles to be measured is 300 or more, and the average value is calculated.

The addition amount of the semiconductor nanoparticles is preferably in the range of 0.01 to 50% by mass, and in the range of 0.5 to 30% by mass, where 100% by mass of all the constituent materials of the semiconductor nanoparticle layer is taken. Is more preferable, and most preferably in the range of 2.0 to 25% by mass. If the addition amount is 0.01% by mass or more, sufficient luminance efficiency can be obtained, and if it is 50% by mass or less, an appropriate inter-particle distance of the semiconductor nanoparticles can be maintained, and the quantum size effect can be sufficiently obtained. Can be expressed.

(1) Preparation of semiconductor nanoparticles <1.1: Constituent material of semiconductor nanoparticles>
Examples of the constituent material of the semiconductor nanoparticle according to the present invention include a simple substance of Group 14 element of the periodic table such as carbon, silicon, germanium and tin, a simple substance of Group 15 element of the periodic table such as phosphorus (black phosphorus), and selenium. And simple substances of Group 16 elements of the periodic table such as tellurium.

Further, compounds composed of a plurality of Group 14 elements of the periodic table such as silicon carbide (SiC), for example, tin (IV) (SnO ₂ ), tin (II, IV) (Sn (II) Sn (IV) S ₃ ), tin sulfide (IV) (SnS ₂ ), tin sulfide (II) (SnS), tin selenide (II) (SnSe), tin telluride (II) (SnTe), lead sulfide (II) (PbS) , Lead selenide (II) (PbSe), lead telluride (II) (PbTe) periodic table group 14 element and periodic table group 16 element compound, boron nitride (BN), boron phosphide (BP ), Boron arsenide (BAs), aluminum nitride (AlN), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), arsenic Gallium phosphide (GaAs Periodic group 13 elements and periodic table group 15 elements such as gallium antimonide (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), etc. (Or III-V group compound semiconductor), aluminum sulfide (Al ₂ S ₃ ), aluminum selenide (Al ₂ Se ₃ ), gallium sulfide (Ga ₂ S ₃ ), gallium selenide (Ga ₂ Se ₃ ), Periods of gallium telluride (Ga ₂ Te ₃ ), indium oxide (In ₂ O ₃ ), indium sulfide (In ₂ S ₃ ), indium selenide (In ₂ Se ₃ ), indium telluride (In ₂ Te ₃ ), etc. Compounds of Group 13 elements and Group 16 elements of the periodic table, thallium chloride (I) (TlCl), thallium bromide (I) ( LBR), include compounds of thallium iodide (I) (TlI) periodic table group 13 elements and the periodic table Group 17 element such.

Furthermore, zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe) and other compounds of Group 12 elements and Group 16 elements (or II-VI compound semiconductors) Arsenic (III) sulfide (As ₂ S ₃ ), arsenic selenide (III) (As ₂ Se ₃ ), arsenic telluride (III) (As ₂ Te ₃ ), antimony sulfide (III) (Sb ₂ S ₃ ) selenide antimony _{(III) (Sb 2 Se 3} ), antimony telluride _{(III) (Sb 2 Te 3} ), bismuth sulfide _{(III) (Bi 2 S 3} ), bismuth selenide (III _(Bi 2 _Se 3), bismuth telluride _{(III) (Bi 2 Te 3} ) Periodic Table compounds of a Group 15 element and Periodic Table Group 16 element such as copper oxide _{(I) (Cu 2 O)} , selenium Examples include compounds of Group 11 elements of the periodic table and Group 16 elements of the periodic table such as copper (I) chloride (Cu ₂ Se).

Further, Group 11 of the periodic table of copper (I) chloride (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), silver chloride (AgCl), silver bromide (AgBr), etc. Compounds of elements and group 17 elements of the periodic table, compounds of group 10 elements of the periodic table and group 16 elements of the periodic table such as nickel oxide (II) (NiO), cobalt (II) oxide (CoO), cobalt sulfide (II) (CoS) periodic table group 9 element and periodic table group 16 element compound, triiron tetroxide (Fe ₃ O ₄ ), iron sulfide (II) (FeS) periodic table 8 A compound of a group element and a group 16 element of the periodic table, a compound of a group 7 element of the periodic table and a group 16 element of the periodic table such as manganese oxide (II) (MnO), molybdenum sulfide (IV) (MoS ₂ ), Compounds of periodic table group 6 elements and periodic table group 16 elements such as tungsten oxide (IV) (WO ₂ ); Compound of periodic table group 5 element and periodic table group 16 element such as vanadium oxide (II) (VO), vanadium oxide (IV) (VO ₂ ), tantalum oxide (V) (Ta ₂ O ₅ ), oxidation Compounds of Group 4 elements of the periodic table and Group 16 elements of the periodic table such as titanium (TiO ₂ , Ti ₂ O ₅ , Ti ₂ O ₃ , Ti ₅ O _9, etc.), magnesium sulfide (MgS), magnesium selenide ( Compounds of Group 2 elements of the periodic table and elements of Group 16 of the periodic table, such as MgSe), cadmium (II) chromium (III) (CdCr ₂ O ₄ ), cadmium selenide (II) chromium (III) (CdCr ₂ Se ₄ ), chalcogen spinels such as copper (II) chromium (III) (CuCr ₂ S ₄ ), mercury selenide (III) (HgCr ₂ Se ₄ ), barium titanate (BaTiO ₃ ), etc. Cited The

In the present invention, a compound of a periodic table group 14 element and a periodic table group 16 element such as SnS ₂ , SnS, SnSe, SnTe, PbS, PbSe, PbTe, GaN, GaP, GaAs, GaSb, InN, InP, III-V group compound semiconductors such as InAs and InSb, Ga ₂ O ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ , In ₂ Te Compounds of Group 13 elements of the periodic table such as ₃ and Group 16 elements of the Periodic Table, II-VI compounds such as ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe _{semiconductor, As 2 O 3, As 2} S 3, As 2 Se 3, As 2 Te 3, Sb 2 O 3, Sb 2 S 3, Sb 2 Se 3, Sb 2 Te 3, _{i 2 O 3, Bi 2 S} 3, Bi 2 Se 3, a compound of the _Bi 2 Te ₃ Periodic Table Group 15 element and Periodic Table Group 16 element such as, MgS, a Group 2 element such as MgSe Compounds with Group 16 elements of the periodic table are preferred, among which Si, Ge, GaN, GaP, InN, InP, Ga ₂ O ₃ , Ga ₂ S ₃ , In ₂ O ₃ , In ₂ S ₃ , ZnO, ZnS, CdO and CdS are more preferable.

Since these substances do not contain highly toxic negative elements, they have excellent resistance to environmental pollution and safety to living organisms. In addition, a pure spectrum can be stably obtained in the visible light region, so that luminescence is achieved. It is advantageous for forming a device. Among these materials, CdSe, ZnSe, and CdS are particularly preferable in terms of light emission stability. On the other hand, semiconductor nanoparticles of ZnO and ZnS are preferred from the viewpoints of luminous efficiency, high refractive index, safety and economy. Moreover, said material may be used by 1 type and may be used in combination of 2 or more type.

The semiconductor nanoparticles described above can be doped with a small amount of various elements as impurities as necessary. By adding such a doping substance, the light emission characteristics can be greatly improved.

In the case of semiconductor nanoparticles that are inorganic substances, the emission wavelength (band gap) as used in the present invention is the band gap (eV) in the semiconductor nanoparticles, and the energy difference between the valence band and the conduction band. nm) = 1240 / band gap (eV).

The band gap (eV) of the semiconductor nanoparticles can be measured using a Tauc plot.

The Tauc plot, which is one of the optical scientific measurement methods of the band gap (eV), will be described.

The measurement principle of the band gap (E ₀ ) using Tauc plot is shown below.

In the vicinity of the optical absorption edge on the long wavelength side of the semiconductor material, in a relatively large absorption region, the light absorption coefficient α, the light energy hν (where h is the Planck constant, ν is the vibration frequency), and the band cap energy E ₀ It is considered that the relationship represented by the following formula (A) is established between them. However, B represents a constant.

Formula (A)
αhν = B (hν−E ₀ ) ²
Therefore, an absorption spectrum is measured, and hν is plotted with respect to (αhν) to the power of 0.5, so-called Tauc plot, and the value of hν at α = 0 obtained by extrapolating the straight section is sought. The band gap energy E ₀ of the semiconductor nanoparticles is obtained.

In the case of semiconductor nanoparticles, since the difference between the absorption and emission spectra (Stokes shift) is small and the waveform is sharp, the maximum wavelength of the emission spectrum can be simply used as an index of the band gap.

As another method for estimating the energy levels of these organic functional materials and inorganic functional materials, energy required by scanning tunneling spectroscopy, ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and the like. There are a method of obtaining from a level and a method of optically estimating a band gap.

The surface of the semiconductor nanoparticles is preferably coated with an inorganic coating layer or a coating composed of an organic ligand. That is, the surface of the semiconductor nanoparticle has a core-shell structure having a core region composed of a semiconductor nanoparticle material and a shell region composed of an inorganic coating layer or an organic ligand. preferable.

This core / shell structure is preferably formed of at least two kinds of compounds, and may form a gradient structure (gradient structure) with two or more kinds of compounds. Thereby, aggregation of the semiconductor nanoparticles in the coating liquid can be effectively prevented, the dispersibility of the semiconductor nanoparticles can be improved, the luminance efficiency is improved, and the optical film of the present invention is used. When the light emitting device is continuously driven, the occurrence of color misregistration can be suppressed. In addition, stable emission characteristics can be obtained due to the presence of the coating layer (shell region).

Further, since the surface of the semiconductor nanoparticles is coated with the coating layer (shell region), a surface modifier as described later can be reliably supported in the vicinity of the surface of the semiconductor nanoparticles.

The thickness of the coating layer (shell region) is not particularly limited, but is preferably in the range of 0.1 to 10 nm, and more preferably in the range of 0.1 to 5 nm.

In general, a semiconductor nanoparticle can control the emission color by its average particle diameter, and if the thickness of the coating layer is within the above range, the thickness of the coating corresponds to the number of atoms. Thus, the thickness is less than one semiconductor nanoparticle, the semiconductor nanoparticle can be filled with high density, and a sufficient amount of light emission can be obtained. In addition, the presence of the coating can suppress non-luminous electron energy transfer due to defects existing on the particle surfaces of the core particles and electron traps on the dangling bonds, thereby suppressing a decrease in quantum efficiency.

<1.2: Manufacturing method of semiconductor nanoparticles>
As a method for producing semiconductor nanoparticles, any conventionally known method can be used. Moreover, it can also be purchased as a commercial product from Aldrich, Crystalplex, NN-Labs, etc.

For example, the production method in a high vacuum environment includes a molecular beam epitaxy method, a CVD method, and the like. As the liquid phase production method, a raw material aqueous solution is used, for example, an alkane such as n-heptane, n-octane, or isooctane. Or a reverse micelle method in which a crystal is grown in a reverse micelle phase in a non-polar organic solvent such as aromatic hydrocarbon such as benzene, toluene, xylene, etc. Examples include a hot soap method in which crystals are grown by injecting into a phase organic medium, and a solution reaction method involving crystal growth at a relatively low temperature using an acid-base reaction as a driving force, as in the hot soap method. Any method can be applied from these production methods, and among these, the liquid phase production method is preferable.

In addition, in the synthesis | combination of the semiconductor nanoparticle by a liquid phase manufacturing method, the organic surface modifier which exists on the surface is called an initial stage surface modifier. For example, examples of the initial surface modifier in the hot soap method include trialkylphosphines, trialkylphosphine oxides, alkylamines, dialkyl sulfoxides, alkanephosphonic acid and the like. These initial surface modifiers are preferably exchanged for the following functional surface modifiers by an exchange reaction.

Specifically, for example, the initial surface modifier such as trioctyl phosphine oxide obtained by the hot soap method described above is subjected to an exchange reaction performed in a liquid phase containing a functional surface modifier, and the following (2) It can be exchanged for the functional surface modifier shown in FIG.

(2) Functional surface modifier The semiconductor nanoparticle according to the present invention is characterized in that its surface is coated with a resin. Before coating with a resin, a surface modifier is applied to the semiconductor nanoparticle. It may be given.

By attaching a surface modifier in the vicinity of the surface of the semiconductor nanoparticles, the dispersion stability of the semiconductor nanoparticles in the coating solution for forming the semiconductor nanoparticle layer can be improved. In addition, when the semiconductor nanoparticles are manufactured, the surface of the semiconductor nanoparticles is attached to the surface of the semiconductor nanoparticles, so that the shape of the formed semiconductor nanoparticles becomes high in sphericity, and the particle size distribution of the semiconductor nanoparticles Can be kept narrow, and therefore can be made particularly excellent.

The functional surface modifier that can be applied in the present invention may be those directly attached to the surface of the semiconductor nanoparticles, or those attached via the shell, that is, the surface modifier is directly attached. May be a shell that is not in contact with the core of the semiconductor nanoparticles.

As specific examples of functional surface modifiers,
1) Polyoxyethylene alkyl ethers: for example, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, etc.
2) Trialkylphosphines: For example, tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, etc.
3) Polyoxyethylene alkylphenyl ethers: for example, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, etc.
4) Tertiary amines: for example, tri (n-hexyl) amine, tri (n-octyl) amine, tri (n-decyl) amine, etc.
5) Organophosphorus compounds: for example, tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tridecylphosphine oxide, etc.
6) Polyethylene glycol diesters: for example, polyethylene glycol dilaurate, polyethylene glycol distearate, etc.
7) Organic nitrogen compounds: For example, nitrogen-containing aromatic compounds of pyridine, lutidine, collidine, quinolines, etc.
8) Aminoalkanes: for example, hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, etc.
9) Dialkyl sulfides: for example, dibutyl sulfide
10) Dialkyl sulfoxides: for example, dimethyl sulfoxide, dibutyl sulfoxide, etc.
11) Organic sulfur compounds: For example, sulfur-containing aromatic compounds such as thiophene, etc.
12) Higher fatty acids: For example, palmitic acid, stearic acid, oleic acid, etc.
13) Others: alcohols, sorbitan fatty acid esters, fatty acid-modified polyesters, tertiary amine-modified polyurethanes, polyethyleneimines, etc.
In the case where the semiconductor nanoparticles are prepared by the method described later, the surface modifier is a substance that is coordinated and stabilized by the fine particles of the semiconductor nanoparticles in a high-temperature liquid phase. Specifically, 2) Trialkylphosphines, 4) Tertiary amines, 5) Organophosphorus compounds, 7) Organonitrogen compounds, 8) Aminoalkanes, 9) Dialkyl sulfides, 10 ) Dialkyl sulfoxides, 11) organic sulfur compounds, 12) higher fatty acids and alcohols are preferred. By using such a surface modifier, the dispersibility of the semiconductor nanoparticles in the coating solution can be made particularly excellent. Moreover, the shape of the semiconductor nanoparticles formed during the production of the semiconductor nanoparticles can be made higher in sphericity, and the particle size distribution of the semiconductor nanoparticles can be made sharper.

In the present invention, polysilazane described later can also be used as a surface modifier.

In the present invention, the size (average particle diameter) of the semiconductor nanoparticles is preferably in the range of 1 to 20 nm. The size of the semiconductor nanoparticles referred to in the present invention is composed of a core region composed of a semiconductor nanoparticle material, a shell region composed of an inert inorganic coating layer or an organic ligand, and a surface modifier. Represents the total size. If the surface modifier or shell is not included, the size does not include it.

(3) Resin component used for coating of semiconductor nanoparticles The semiconductor nanoparticles according to the present invention are characterized in that their surfaces are coated with a resin, and it is preferable that the resin is a transparent resin. is there. The semiconductor nanoparticles coated with the resin according to the present invention may be either in a state having the surface modifier on the surface or in a state having no surface modifier.

The transparent resin referred to in the present invention means a resin having optical transparency, and more specifically, the visible light transmittance is 60% or more, preferably 80% or more, more preferably 90%. That's it. Therefore, the transparent resin referred to in the present invention is a resin having the above transmittance in the visible light region, and the transparent resin covering the surface of the semiconductor nanoparticles according to the present invention is not limited as long as it satisfies the above conditions. In particular, an ultraviolet curable resin or a water-soluble resin is preferable.

Hereinafter, details of the ultraviolet curable resin and the water-soluble resin suitable as the resin according to the present invention will be described.

<3.1: UV curable resin>
In the present invention, it is one of preferred embodiments that the surface of the semiconductor nanoparticles is coated with an ultraviolet curable resin.

Examples of the ultraviolet curable resin applicable to the present invention include radical polymerization such as an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, and an ultraviolet curable polyol acrylate resin. A cationic polymerizable resin such as a functional resin or an ultraviolet curable epoxy resin is preferably used. Among these, an ultraviolet curable acrylate resin which is a radical polymerizable resin is preferable.

UV curable urethane acrylate resins are generally obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer, and further adding 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate (hereinafter referred to as methacrylate to the acrylate). It can be easily obtained by reacting an acrylate monomer having a hydroxy group such as 2-hydroxypropyl acrylate. For example, those described in JP-A-59-151110 can be used. Specifically, a mixture of 100 parts Unidic 17-806 (manufactured by DIC Corporation) and 1 part of Coronate L (manufactured by Nippon Polyurethane Corporation) is preferably used.

Examples of the UV curable polyester acrylate resin include those that are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyol. No. 151112 can be used.

Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate oligomer, a reactive diluent and a photopolymerization initiator added to the oligomer, and a reaction product. Those described in JP-A No. 1-105738 can be used.

Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

In the present invention, polymethyl methacrylate and polylauryl methacrylate obtained by polymerizing methyl methacrylate or lauryl methacrylate using ultraviolet rays are also classified as ultraviolet curable resins according to the present invention.

Specific examples of the photopolymerization initiator used for forming these ultraviolet curable resins include benzoin and its derivatives, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof. Can do. You may use with a photosensitizer. The photopolymerization initiator can also be used as a photosensitizer. Further, when an epoxy acrylate photopolymerization initiator is used, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used. The photopolymerization initiator or photosensitizer used in the ultraviolet curable resin composition is in the range of 0.1 to 15 parts by mass, preferably in the range of 1 to 10 parts by mass, per 100 parts by mass of the composition. is there.

In the present invention, the resin coverage when the resin is coated on the surface of the semiconductor nanoparticles according to the present invention is not particularly limited, but when the total mass of the semiconductor nanoparticles coated with the resin is 100% by mass The ratio of the resin to be coated is preferably in the range of 5 to 50% by mass, more preferably in the range of 10 to 35% by mass, and still more preferably in the range of 15 to 30% by mass. is there.

In addition, as a method for coating the surface of the semiconductor nanoparticles according to the present invention with a resin such as an ultraviolet curable resin, an ultraviolet curable resin is added to the solution containing the semiconductor nanoparticles while the surface of the semiconductor nanoparticles is irradiated with ultraviolet rays. A method of forming a resin on the surface of the semiconductor nanoparticle by coating the curable resin and then subjecting the semiconductor nanoparticle coated with the ultraviolet curable resin to UV curing by ultraviolet irradiation, or UV curing on the surface of the semiconductor nanoparticle. UV curable resin is applied to the particle surface by a solution polymerization method in a solution in which semiconductor nanoparticles are present, or after applying a functional resin using a spray-type wet coating apparatus such as a spray coater. Examples of the method include a method of preparing semiconductor nanoparticles coated with a resin by performing UV curing after coating.

In the present invention, as a method for confirming whether or not the surface of the semiconductor nanoparticles according to the present invention is coated, the prepared semiconductor nanoparticles coated with the resin are, for example, focused ion beam (FB-) manufactured by Hitachi High-Technologies. 2000A), a cross section is processed, and a surface passing through the vicinity of the particle center is cut out. Next, by observing the exposed cut surface of the center line with an electron microscope, the presence or absence of the coating resin, the thickness of the coated resin layer, and the ratio of the coated resin to the entire particles can be determined.

Also, as another method, similarly, a cross section is processed by a focused ion beam (FB-2000A) manufactured by Hitachi High-Technologies, and a surface passing near the particle center is cut out. Then, from the cut surface, it can also be obtained by performing elemental analysis using STEM-EDX (HD-2000) manufactured by Hitachi High-Technologies, and measuring the composition distribution of the resin component and the semiconductor nanoparticle component.

As a light source applied to the UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. The irradiation conditions vary depending on individual irradiation light source, the irradiation amount of ultraviolet rays is usually within the range of 5 ~ 500mJ / cm ^2, preferably in the range of 5 ~ 150mJ / cm ^2.

<3.2: Water-soluble resin>
In the present invention, it is also a preferred embodiment to use a water-soluble resin as the resin for coating the semiconductor nanoparticles.

The water-soluble resin applicable to the present invention is not particularly limited, but polyvinyl alcohol resins, gelatin, celluloses, thickening polysaccharides, and resins having reactive functional groups can be used. Of these, it is preferable to use a polyvinyl alcohol-based resin. The water-soluble in the present invention means a compound in which 1% by mass or more, preferably 3% by mass or more dissolves in an aqueous medium.

Examples of the polyvinyl alcohol resin preferably used in the present invention include, in addition to normal polyvinyl alcohol (unmodified polyvinyl alcohol) obtained by hydrolysis of polyvinyl acetate, cation-modified polyvinyl alcohol having a terminal cation-modified, anion Anionic modified polyvinyl alcohol having a functional group, modified polyvinyl alcohol modified with acrylic, reactive polyvinyl alcohol (for example, “Gosefimer Z” manufactured by Nihon Gosei Co., Ltd.), vinyl acetate resin (for example, “Kuraray Co., Ltd.” "Exeval") is also included. These polyvinyl alcohol-based resins can be used in combination of two or more different polymerization degrees and different types of modification. Further, silanol-modified polyvinyl alcohol having a silanol group (for example, “R-1130” manufactured by Kuraray Co., Ltd.) can be used in combination.

Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups as described in JP-A No. 61-10383. Polyvinyl alcohol contained therein and obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-307979. Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group is added to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. The block copolymer of the vinyl compound and vinyl alcohol which have the described hydrophobic group is mentioned. Polyvinyl alcohol can be used in combination of two or more different degrees of polymerization and different types of modification.

Examples of vinyl acetate resins include Exeval (trade name: manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (trade name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

The polymerization degree of the polyvinyl alcohol-based resin is preferably in the range of 1500 to 7000, and more preferably in the range of 2000 to 5000. A polymerization degree of 1500 or more is preferable because crack resistance of the coating film during formation of the refractive index layer is improved. On the other hand, when the degree of polymerization is 7000 or less, the coating liquid at the time of forming the refractive index layer is preferable.

As a method of coating the surface of the semiconductor nanoparticles according to the present invention with a resin such as a water-soluble resin, the semiconductor nanoparticles are formed by immersing the semiconductor nanoparticles in a solution containing the water-soluble resin under vacuum for a certain period of time. Can do.

<3.3: Other resins>
In addition, as resin which coat | covers a semiconductor nanoparticle, thermoplastic resins, such as a polymethylmethacrylate resin (PMMA; Poly (methyl methacrylate)), may be sufficient, for example, An acrylic polyol and an isocyanate prepolymer A thermosetting resin such as a thermosetting urethane resin, a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, or a silicone resin may be used.

<Polysilazane and modified polysilazane>
In the optical film of the present invention, the constituent semiconductor nanoparticle layer contains at least one compound selected from polysilazane and a modified polysilazane.

The polysilazane modified product is preferably a compound that is generated by subjecting polysilazane to a modification treatment and includes at least one selected from silicon oxide, silicon nitride, and silicon oxynitride.

Here, the polysilazane may be dispersed together with the semiconductor nanoparticles in the coating solution for forming the semiconductor nanoparticle layer, or the semiconductor nanoparticles are coated with polysilazane in advance, and the particles are in the coating solution for forming the semiconductor nanoparticle layer. May be dispersed. In the present invention, the term “covering” means covering the surface of the semiconductor nanoparticles, but the surface of the semiconductor nanoparticles may not cover all, but covers a part. It may be. Whether or not this condition is satisfied can be determined by analyzing the structure of the semiconductor nanoparticles coated with the resin by the above confirmation method.
By providing at least one compound of polysilazane and a modified polysilazane in the semiconductor nanoparticle layer, the semiconductor nanoparticle layer is provided with durability capable of suppressing contact of the semiconductor nanoparticles with oxygen or the like over a long period of time. Furthermore, it can be set as a highly transparent layer.

(1) Constituent material of polysilazane “Polysilazane” as used in the present invention is a polymer having a silicon-nitrogen bond, and is composed of SiO ₂ , Si ₃ N ₄ composed of Si—N, Si—H, NH, etc. Ceramic precursor inorganic polymer such as intermediate solid solution SiO _x N _y . A polysilazane and a polysilazane derivative are compounds having a structure represented by the following general formula (I).

 

In order to apply so as not to impair the flatness of the base material, it is preferable to use a ceramic material which is converted to silica at a relatively low temperature as described in JP-A-8-112879.

In general formula (I), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylsilyl group, an alkylamino group or an alkoxy group. .

Perhydropolysilazane (PHPS) in which all of R ₁ , R ₂ and R ₃ are hydrogen atoms is particularly preferred from the viewpoint of the denseness of the resulting layer.

On the other hand, organopolysilazane in which part of the hydrogen part bonded to Si is substituted with an alkyl group or the like has an alkyl group such as a methyl group, so that the adhesion to the base material is improved and the polysilazane which is hard and brittle It is possible to impart toughness to the ceramic film by the above, and there is an advantage that generation of cracks can be suppressed even when the (average) film thickness is increased. These perhydropolysilazane and organopolysilazane may be appropriately selected according to the application, and can also be mixed and used.

Perhydropolysilazane is presumed to have a linear structure and a ring structure centered on 6- and 8-membered rings. Its molecular weight is about 600 to 2000 (polystyrene conversion) in terms of number average molecular weight (Mn), is a liquid or solid substance, and varies depending on the molecular weight. These are commercially available in a solution state dissolved in an organic solvent, and the commercially available product can be used as it is as a polysilazane-containing liquid.

As another example of polysilazane which is ceramicized at a low temperature, a silicon alkoxide-added polysilazane obtained by reacting the polysilazane represented by the general formula (I) with a silicon alkoxide (see, for example, JP-A No. 5-23827), glycidol A glycidol-added polysilazane obtained by reacting (see, for example, JP-A-6-122852), an alcohol-added polysilazane obtained by reacting an alcohol (see, for example, JP-A-6-240208), and a metal carboxylate Metal carboxylate-added polysilazane obtained by reaction (for example, see JP-A-6-299118), acetylacetonate complex-added polysilazane obtained by reacting a metal-containing acetylacetonate complex (for example, JP-A-6-299) No. 306329 Irradiation), fine metal particles of the metal particles added polysilazane obtained by adding (e.g., JP-see JP 7-196986), and the like.

Also, amines and metal catalysts can be added to the semiconductor nanoparticle layer in order to promote the conversion of polysilazane into a silicon oxide compound. Specific examples include Aquamica NAX120-20, NN110, NN310, NN320, NL110A, NL120A, NL150A, NP110, NP140, and SP140 manufactured by AZ Electronic Materials.

(2) Modification treatment The modification treatment is preferably performed on the polysilazane contained in the semiconductor nanoparticle layer, whereby a part or all of the polysilazane contained in the semiconductor nanoparticle layer is modified by polysilazane modification. Become a body.

When polysilazane is dispersed together with semiconductor nanoparticles in the coating solution for forming a semiconductor nanoparticle layer, the modification treatment is performed on the coating layer formed by coating the coating solution for forming a semiconductor nanoparticle layer. .

Further, when the semiconductor nanoparticles are coated with polysilazane in advance, the modification treatment may be performed in advance on the semiconductor nanoparticles coated with the polysilazane, or may be coated with the polysilazane. It may be performed on the coating layer formed by coating the semiconductor nanoparticles, or may be performed on both.

Specifically, for the modification treatment, a known method based on the conversion reaction of polysilazane can be selected. Production of a silicon oxide film or a silicon oxynitride film by a substitution reaction of a silazane compound requires a heat treatment at 450 ° C. or more, and is difficult to apply to a flexible substrate such as plastic. In order to apply to a plastic substrate, it is preferable to use a method such as plasma treatment, ozone treatment, or ultraviolet irradiation treatment that allows the conversion reaction to proceed at a low temperature.

In addition, when performing a modification process with respect to the coating layer containing polysilazane, it is preferable that the water | moisture content is removed before the said modification process.

In the present invention, as the modification treatment, ultraviolet irradiation, vacuum ultraviolet irradiation (excimer irradiation), and plasma irradiation are desirable, and vacuum ultraviolet irradiation (also referred to as VUV) is particularly preferable from the viewpoint of the modification effect of polysilazane.

(2-1) Ultraviolet irradiation treatment As the modification treatment method, treatment by ultraviolet irradiation is also preferred. Ozone and active oxygen atoms generated by ultraviolet light (synonymous with ultraviolet light) have high oxidation ability, and modify polysilazane at low temperature to produce silicon oxide or silicon oxynitride with high density and insulation. Is possible.

In the present invention, any commonly used ultraviolet ray generator can be used.

In this example, “ultraviolet rays” generally refers to electromagnetic waves having a wavelength in the range of 10 to 400 nm, but in the case of ultraviolet irradiation treatment in order to distinguish from the vacuum ultraviolet ray (10 to 200 nm) treatment described later. Preferably uses ultraviolet rays in the range of 210 to 350 nm.

For UV irradiation, set the irradiation intensity and irradiation time as long as the substrate carrying the applied coating film is not damaged.

Examples of the ultraviolet ray generation method used for the modification include a metal halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a xenon arc lamp, a carbon arc lamp, and an excimer lamp (single wavelengths of 172 nm, 222 nm, and 308 nm, for example, USHIO (Made by Co., Ltd.), UV light laser etc. are mentioned, It does not specifically limit. In addition, when irradiating the applied ultraviolet rays to the coating layer, a method of applying the ultraviolet rays from the generation source to the coating layer after reflecting the ultraviolet rays from the generation source is desirable in order to achieve uniform irradiation and improve efficiency. .

UV irradiation can be adapted to either batch processing or continuous processing, and can be appropriately selected depending on the shape of the substrate to be coated.

(2-2) Vacuum Ultraviolet Irradiation Treatment; Excimer Irradiation Treatment In the present invention, a more preferable modification treatment method is treatment by vacuum ultraviolet radiation. The treatment by vacuum ultraviolet irradiation uses light energy in the range of 100 to 200 nm, preferably light energy having a wavelength in the range of 100 to 180 nm, which is larger than the interatomic bonding force in the silazane compound, and bonds the atoms. This is a method of forming a silicon oxide film at a relatively low temperature by causing an oxidation reaction with active oxygen or ozone to proceed while cutting directly by the action of only photons called a photon process.

As a vacuum ultraviolet light source necessary for this, a rare gas excimer lamp is preferably used.

The detailed contents and specific conditions of the vacuum ultraviolet irradiation treatment (excimer irradiation treatment) are not particularly limited. For example, paragraphs [0079] to [0091] of JP 2011-031610 A The contents described therein or the contents described in paragraph numbers [0086] to [0098] of JP 2012-016854 A can be referred to.

<Light emitting device>
The light-emitting device of the present invention includes an optical film containing the above-described semiconductor nanoparticles of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a light-emitting device provided with an optical film containing the semiconductor nanoparticles of the present invention.

2, the light emitting device 1 includes a blue or ultraviolet light source 3 (also referred to as a primary light source) and an image display panel 2 disposed in an optical path from the light source 3. The image display panel 2 includes an image display layer 7 such as a liquid crystal layer.

Components such as a substrate for supporting the image display layer 7, electrodes and drive circuits for driving the image display layer, and an alignment film for aligning the liquid crystal layer in the case of the liquid crystal image display layer are shown in FIG. It is omitted in 2.

In the light emitting device 1 shown in FIG. 2, the image display layer 7 is a pixelated image display layer. In the image display layer 7, individual regions (“pixels”) of the image display layer are used as other regions. And can be driven independently.

The light-emitting device 1 of the present invention is intended to provide a color display. Therefore, the image display panel 2 is provided with a color filter unit 6. In the case of a full-color red, green, and blue (RGB) display, the image display panel 2 includes a red color filter 6R, a blue color filter 6B, and a green color filter 6G, as shown in the figure. A plurality of filter set units 6 are provided. The individual color filters are aligned with the pixels or sub-pixels of each image display layer 7 and installed.

In the light emitting device 1, the light source 3 may include one or more light emitting diodes (LEDs), and is preferably a blue light source or an ultraviolet light source.

The light emitting device 1 has a light guide 5 as an optical system that enables the image display panel 2 to be illuminated substantially uniformly by light from the light source 3. In FIG. 2, the optical system includes a light guide 5 having a light emission surface 5 a that has substantially the same extent as the image display panel 2. The light from the light source 3 enters the light guide 8 along the light incident surface 5b, is reflected in the light guide 5 according to the principle of total internal reflection, and finally the light emission surface 5a of the light guide. Radiated from. The light guide body having such a configuration is publicly known, and details of the light guide body 5 are omitted here. The optical film 4 of the present invention is provided on the emission surface 5 a of the light guide 5.

The optical film 4 containing the semiconductor nanoparticles of the present invention emits light in a plurality of wavelength ranges different from each other and different from the emission wavelength range of the primary light source 3 when illuminated by light from the primary light source 3. It is preferably composed of two or more different materials. The primary light source 3 preferably emits light outside the visible spectrum region (for example, light in the ultraviolet (UV) region) or blue light.

Furthermore, the color filter unit 6 shown in FIG. 2 includes a color filter having a narrow transmission band. The narrow transmission band filter preferably has a full width at half maximum (FWHM) of 100 nm or less, and particularly preferably has a FWHM of 80 nm or less.

Moreover, in FIG. 2, although the optical film 4 containing the semiconductor nanoparticle of this invention demonstrated the example provided on the discharge | release surface 5a of the light guide 5, in the light-emitting device 1 of this invention, an optical film 4 may be provided inside the light guide 5 main body. For example, the semiconductor nanoparticles according to the present invention are disposed in a suitable transparent matrix, for example, in a resin that is molded to have a desired shape of the light guide 5 and then curved. It can be set as the optical film 4 comprised.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

Example 1
<Synthesis of semiconductor nanoparticles>
[Synthesis of Semiconductor Nanoparticle A: Core / Shell InP / ZnS Semiconductor Nanoparticle A]
Indium myristate 0.1 mmol, stearic acid 0.1 mmol, trimethylsilylphosphine 0.1 mmol, dodecanethiol 0.1 mmol, and undecylenic acid zinc 0.1 mmol were placed in a three-necked flask together with octadecene 8 ml and refluxed under a nitrogen atmosphere. The mixture was heated at 0 ° C. for 1 hour to obtain an octadecene solution containing InP / ZnS (semiconductor nanoparticles). Then, it dried under vacuum and obtained InP / ZnS semiconductor nanoparticle A powder. In the present invention, the semiconductor nanoparticle A having a core / shell structure is represented by InP / ZnS, where the core is InP and the shell is ZnS.

The semiconductor nanoparticle A was directly observed with a transmission electron microscope, and it was confirmed that the surface of the InP core part was an InP / ZnS semiconductor nanoparticle having a core / shell structure coated with a ZnS shell. Further, according to this observation, the InP / ZnS semiconductor nanoparticles A synthesized by this synthesis method have a core part particle diameter in the range of 2.1 to 3.8 nm and a core part particle size distribution of 6 to 40. %. Here, a JEM-2100 transmission electron microscope manufactured by JEOL Ltd. was used for the observation.

Also, the optical properties of the InP / ZnS semiconductor nanoparticles A were measured using an octadecene solution containing the semiconductor nanoparticles A. It was confirmed that the emission peak wavelength was in the range of 430 to 720 nm, and the emission half width was in the range of 35 to 90 nm. The luminous efficiency reached a maximum of 70.9%. Here, a fluorescence spectrophotometer FluoroMax-4 manufactured by JOBIN YVON is used to measure the emission characteristics of InP / ZnS semiconductor nanoparticles A, and a spectrophotometer manufactured by Hitachi High-Technologies Corporation is used to measure the absorption spectrum. A total of U-4100 was used.

[Synthesis of Semiconductor Nanoparticle B: CdSe / ZnS Semiconductor Nanoparticle B with Core / Shell Structure]
0.7896 g of Se powder was added to 7.4 g of trioctylphosphine (abbreviation: TOP), the mixture was heated to 150 ° C., and a TOP-Se stock solution was prepared under a nitrogen stream. Separately, 0.450 g of cadmium oxide (CdO) and 8 g of stearic acid were heated to 150 ° C. in a three-necked flask under an argon atmosphere. After CdO was dissolved, the CdO solution was cooled to room temperature. To this CdO solution, 8 g of trioctylphosphine oxide (abbreviation: TOPO) and 12 g of 1-heptadecyl-octadecylamine (abbreviation: HDA) were added, and the mixture was heated again to 150 ° C., where the TOP-Se stock solution was added. Added quickly.

Thereafter, the temperature of the chamber was heated to 220 ° C., and further increased to 250 ° C. over 120 minutes at a constant rate (0.25 ° C./min). Thereafter, the temperature was lowered to 100 ° C., zinc acetate dihydrate was added and dissolved by stirring, and then a trioctylphosphine solution of hexamethyldisilylthiane was dropped, and stirring was continued for several hours to complete the reaction. CdSe / ZnS (semiconductor nanoparticles) was obtained. Then, it dried under vacuum and obtained CdSe / ZnS semiconductor nanoparticle B powder.

Similarly to the semiconductor nanoparticle A, the synthesized semiconductor nanoparticle B is directly observed with a transmission electron microscope, whereby a CdSe / ZnS semiconductor nanoparticle having a core / shell structure in which the surface of the CdSe core is covered with a ZnS shell. I was able to confirm that. In addition, it was confirmed that the CdSe / ZnS semiconductor nanoparticles B had a core part particle size in the range of 2.0 to 4.0 nm and a core part particle size distribution in the range of 6 to 40%. As for the optical characteristics, it was confirmed that the emission peak wavelength was in the range of 410 to 700 nm and the emission half width was in the range of 35 to 90 nm. The luminous efficiency reached a maximum of 73.9%.

[Synthesis of Semiconductor Nanoparticle C: Core / Shell InP / ZnS Semiconductor Nanoparticle C Surface-Modified with Thiol Comonomer]
Polystyrene microspheres having 1.0% divinylbenzene (abbreviation: DVB) and 1.0% thiol comonomer were suspended in toluene (1 ml) by shaking and sonication. The microspheres were centrifuged (6000 rpm, about 1 minute), and the supernatant was drained. Washing with toluene was repeated, after which the microspheres were resuspended in toluene (1 ml).

Next, the synthesized core / shell structure InP / ZnS semiconductor nanoparticles A were dispersed in 0.5 ml of chloroform, and then filtered to remove insoluble matters. The semiconductor nanoparticle A-chloroform dispersion was added to the microspheres dispersed in toluene prepared above, and shaken on a shaker plate at room temperature for 16 hours for thorough mixing.

Next, the semiconductor nanoparticles A-microspheres were centrifuged and settled, and the supernatant liquid containing excess semiconductor nanoparticles A was drained. The precipitate was washed twice with 2 ml of toluene, and the washed precipitate was resuspended in toluene (2 ml) and then transferred to a glass sample Bayer tube. A core-shell structure InP surface-modified with a thiol comonomer, placed on the inside of the centrifuge tube, centrifuged, and separated from excess toluene by sedimentation at the bottom of the glass Bayer tube and separation. / ZnS semiconductor nanoparticle C powder was obtained.

[Synthesis of Semiconductor Nanoparticle D: Core-Shell Structured CdSe / ZnS Semiconductor Nanoparticle D Surface-Modified with Thiol Comonomer]
In the synthesis of the InP / ZnS semiconductor nanoparticles C, except that the core / shell structure CdSe / ZnS semiconductor nanoparticles B were used instead of the core / shell structure InP / ZnS semiconductor nanoparticles A, A powder of CdSe / ZnS semiconductor nanoparticles D having a core / shell structure surface-modified with a thiol comonomer was obtained.

[Synthesis of Semiconductor Nanoparticle E: InP / ZnS Semiconductor Nanoparticle E with Core / Shell Structure Coated with Polyvinyl Alcohol]
Prepare a stock solution by dissolving 0.05 g of poly (vinyl alcohol) (87-89% hydrolyzate, MW = 85000-124000) at 100 ° C. in 5 ml of ethylene glycol at 100 ° C. did. Next, the core / shell structure InP / ZnS semiconductor nanoparticle A powder is added to the stock solution of poly (vinyl alcohol) / ethylene glycol and mixed in a nitrogen gas atmosphere, and stored overnight under high vacuum. Thus, a powder of InP / ZnS semiconductor nanoparticles E having a core / shell structure in which the particle surface was coated with polyvinyl alcohol was obtained.

[Synthesis of Semiconductor Nanoparticle F: Core / Shell CdSe / ZnS Semiconductor Nanoparticle F Coated with Polyvinyl Alcohol]
In the synthesis of the semiconductor nanoparticles E, the surface of the particles was similarly obtained except that the core / shell structure CdSe / ZnS semiconductor nanoparticles B were used instead of the core / shell structure InP / ZnS semiconductor nanoparticles A. A powder of CdSe / ZnS semiconductor nanoparticles F having a core / shell structure coated with polyvinyl alcohol was obtained.

[Synthesis of Semiconductor Nanoparticle G: Core / Shell InP / ZnS Semiconductor Nanoparticle G Coated with UV-Curable Resin 1]
25 mg of InP / ZnS semiconductor nanoparticles C powder having a core / shell structure prepared by surface modification with the thiol comonomer was dispersed in degassed methyl methacrylate (abbreviation: MMA). Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide as a photoinitiator and trimethylolpropane trimethacrylate (abbreviation: TMPTM) as a crosslinking agent were added, and the solution was dissolved while degassing. Then, TMPTM which is a crosslinking agent was added to the liquid mixture of MMA and the semiconductor nanoparticle C, and the mixture of the monomer and the crosslinking agent was stirred with a whirl mixer. The prepared slurry was transferred to a syringe, and then continuously stirred at 1200 rpm while being poured into 5 ml of 2% polyvinyl acetate (abbreviation: PVAc) deaerated from the syringe. The suspension was then exposed to 365 nm UV light for 30 minutes. The mixture was stirred overnight and separated the next morning by washing and centrifuging. Washing was performed twice with 20 mL H ₂ O and twice with 20 mL ethanol, and centrifugation was performed at 2000 rpm for 2 minutes between washes. Finally the isolate was dried under vacuum and purged with nitrogen gas. In this manner, a powder of InP / ZnS semiconductor nanoparticles G having a core / shell structure coated with polymethyl methacrylate (abbreviation: PMMA) was obtained.

[Synthesis of Semiconductor Nanoparticle H: CdSe / ZnS Semiconductor Nanoparticle H with Core / Shell Structure Coated with UV Curing Resin 1]
In the synthesis of the semiconductor nanoparticles G, instead of the core / shell structure InP / ZnS semiconductor nanoparticles C surface-modified with thiol comonomer, the core / shell structure CdSe / ZnS semiconductor nanoparticles surface-modified with thiol comonomer A powder of CdSe / ZnS semiconductor nanoparticles H having a core / shell structure coated with an ultraviolet curable resin (PMMA) was obtained in the same manner except that D was used.

[Synthesis of Semiconductor Nanoparticle I: InP / ZnS Semiconductor Nanoparticle I with Core / Shell Structure Coated with UV-Curable Resin 2]
In the synthesis of the semiconductor nanoparticles G, an InP / ZnS semiconductor having a core / shell structure coated with an ultraviolet curable resin (PLMA) is used in the same manner except that lauryl methacrylate (LMA) is used instead of methyl methacrylate (MMA). Nanoparticle I powder was obtained.

[Synthesis of Semiconductor Nanoparticle J: Core-Shell Structure CdSe / ZnS Semiconductor Nanoparticle J Coated with UV-Curable Resin 2]
In the synthesis of the semiconductor nanoparticles H, a core / shell structure CdSe / ZnS coated with an ultraviolet curable resin (PL) is used in the same manner except that lauryl methacrylate (LMA) is used instead of methyl methacrylate (MMA). Semiconductor nanoparticle J powder was obtained.

[Synthesis of Semiconductor Nanoparticle K: InP / ZnS Semiconductor Nanoparticle K with Core / Shell Structure Coated with Silica]
To 70 mg of the prepared InP / ZnS semiconductor nanoparticles A, 0.1 ml of 3- (trimethoxysilyl) propyl methacrylate (abbreviation: TMOPM) and 0.5 ml of triethyl orthosilicate (abbreviation: TEOS) were injected. InP / ZnS semiconductor nanoparticles A having a core / shell structure were dispersed and a dispersion was prepared, followed by overnight incubation in a nitrogen atmosphere. The dispersion was then poured into 10 ml inverse microemulsion (cyclohexane / CO-520 (see below) = 18 ml / 1.35 g) in a 50 ml flask under stirring at 600 rpm and the mixture was stirred for 15 minutes. Then, 0.1 ml of 4% NH ₄ OH was added to initiate the formation reaction of the coating layer on the particle surface. The reaction was stopped by centrifugation on the next day, and the solid phase (particles) was separated. The obtained particles were washed twice with 20 ml of cyclohexane and dried under vacuum to obtain a powder of InP / ZnS semiconductor nanoparticles K having a core / shell structure in which silica was coated on the particle surfaces.

CO-520: Igepal (registered trademark) CO-520 (nonionic surfactant), polyoxyethylene (5) nonylphenyl ether [4- (C ₉ H ₁₉ ) C ₆ H ₄ O (CH ₂ CH ₂ O) ₄ CH ₂ CH ₂ OH]
[Preparation of Semiconductor Nanoparticle L: Preparation of Semiconductor Nanoparticle L with InP Structure Coated with UV-Curable Resin 1]
(Preparation of semiconductor nanoparticles L ₁ having an InP structure)
In accordance with the contents described in paragraph number (0105) of JP 2013-505347 A, semiconductor nanoparticles L ₁ having an InP structure were prepared by the following method.

Dibutyl ester (100 ml) and myristic acid (10.0627 g) were placed in a three-necked flask and degassed at 70 ° C. under vacuum for 1 hour. Nitrogen gas was then introduced and the temperature was raised to 90 ° C. ZnS molecular cluster [Et ₃ NH ₄ ] [Zn ₁₀ S ₄ (SPh) ₁₆ ] (4.77076 g) was added and the mixture was stirred for 45 minutes. Then, after raising the temperature to 100 ° C., In (MA) ₃ (1 mol / L, 15 ml) was added dropwise (TMS) ₃ P (1 mol / L, 15 ml). The temperature was raised to 140 ° C. while stirring the reaction mixture. At 140 ° C., In (MA) ₃ (1 mol / L, 35 ml) (with stirring for 5 minutes) and (TMS) ₃ P (1 mol / L, 35 ml) were further added dropwise. Thereafter, the temperature was slowly raised to 180 ° C., and In (MA) ₃ (1 mol / L, 55 ml) was added dropwise (TMS) ₃ P (1 mol / L, 40 ml). By adding the precursor as described above, the maximum emission value gradually increased from 520 nm to a maximum of 700 nm as InP nanoparticles grew. This allows the reaction to be stopped when the desired emission maximum is obtained and can be left stirring at this temperature for half an hour. After this period, the temperature was lowered to 160 ° C. and the reaction mixture was allowed to anneal for up to 4 days (at a temperature 20-40 ° C. below the temperature of the reaction). A UV lamp was also used at this stage to assist the anneal.

Via the cannula technique, degassed dry methanol (about 200 ml) was added to separate the nanoparticles. After allowing the precipitate to settle, the methanol was removed via a cannula with the help of a filter rod. Degassed dry chloroform (about 10 ml) was added to wash the solids. The solid was dried under vacuum for 1 day. Thereby, 5.60 g of semiconductor nanoparticles L ₁ having an InP structure were prepared.

The InP semiconductor nanoparticles L ₁ prepared as described above were washed with dilute hydrofluoric acid (HF) acid. Semiconductor nanoparticles L were dissolved in degassed anhydrous chloroform (˜270 ml). A 50 ml portion was removed and placed in a plastic flask and flushed with nitrogen. Using a plastic syringe, 3 ml of 60 wt / wt% HF was added to water and added to degassed tetrahydrofuran (THF) (17 ml) to make an HF solution. HF was added dropwise to the semiconductor nanoparticles L over 5 hours. After the addition was complete, the solution was left stirring overnight. Excess HF was removed by drying the etched InP semiconductor nanoparticles L ₁ through extraction with an aqueous calcium chloride solution.

(Preparation of semiconductor nanoparticles L ₂ having an InP structure surface-modified with thiol comonomer)
In the synthesis of the InP / ZnS semiconductor nanoparticles C, a thiol comonomer was used in the same manner except that the semiconductor nanoparticles L ₁ having the InP structure were used instead of the core / shell structure InP / ZnS semiconductor nanoparticles A. to obtain a powder of semiconductor nanoparticles L ₂ having a surface modified InP structure.

(Preparation of semiconductor nanoparticles L having InP structure coated with UV curable resin 1)
In the synthesis of the semiconductor nanoparticles G, instead of the core / shell structure InP / ZnS semiconductor nanoparticles C surface-modified with a thiol comonomer, the semiconductor nanoparticles L ₂ having an InP structure surface-modified with the thiol comonomer prepared above. A semiconductor nanoparticle L powder having an InP structure coated with an ultraviolet curable resin (PMMA) was obtained in the same manner except that was used.

[Preparation of Semiconductor Nanoparticle M: Preparation of Semiconductor Nanoparticle M with CdSe Structure Coated with Ultraviolet Curing Resin 1]
(Preparation of semiconductor nanoparticles M ₁ having a CdSe structure)
In accordance with the method described in paragraph number (0103) of JP 2013-505347 A, semiconductor nanoparticles M ₁ having a CdSe structure were prepared.

HDA (500 g) was placed in a three-necked round bottom flask and heated to 120 ° C. for 1 hour or more under dynamic vacuum to dry and degas. The solution was then cooled to 60 ° C. To this was added 0.718 g of [HNEt ₃ ] ₄ [Cd ₁₀ Se ₄ (SPh) ₁₆ ] (0.20 mmol). In total, 42 mmol, 22.0 ml of TOPSe, and 42 mmol (19.5 ml, 2.15 M) of Me ₂ Cd · TOP were used. First, 4 mmol of TOPSe and 4 mmol of Me ₂ Cd · TOP were added to the reaction solution at room temperature, and the temperature was raised to 110 ° C. and stirred for 2 hours. The reaction solution was dark yellow, and the temperature was gradually raised at a rate of ˜1 ° C./5 min while adding equimolar amounts of TOPSe and Me ₂ Cd · TOP dropwise. When the PL emission maximum reached ˜600 nm, the reaction was stopped by cooling to 60 ° C. and then adding 300 ml of dry ethanol or acetone. This produced a deep red particle precipitate that was further separated by filtration. The resulting CdSe particles were redissolved in toluene and then filtered through celite followed by recrystallization from warm ethanol to remove any excess HDA, selenium or cadmium present. This produced 10.10 g of CdSe semiconductor nanoparticles M ₁ capped with HDA.

(Preparation of semiconductor nanoparticles M ₂ having a surface modified CdSe structure thiol comonomers)
In the synthesis of the InP / ZnS semiconductor nanoparticles C, a thiol comonomer is used in the same manner except that the semiconductor nanoparticles M ₁ having the CdSe structure are used instead of the core / shell structure InP / ZnS semiconductor nanoparticles A. to obtain a powder of semiconductor nanoparticles M ₂ having a surface modified CdSe structure.

(Preparation of semiconductor nanoparticles M having CdSe structure coated with UV curable resin 1)
In the synthesis of the semiconductor nanoparticles G, instead of the core / shell structure InP / ZnS semiconductor nanoparticles C surface-modified with thiol comonomer, semiconductor nanoparticles M ₂ having a CdSe structure surface-modified with thiol comonomer were used. In the same manner, a powder of semiconductor nanoparticles M having a CdSe structure coated with an ultraviolet curable resin (PMMA) was obtained.

<< Production of optical film >>
Using the semiconductor nanoparticles C to M prepared as described above, optical films 1 to 22 were produced by the following method. In addition, preparation and application | coating of the coating liquid were performed in the environment which interrupted | blocked UV light.

[Preparation of optical film 1]
In the preparation of semiconductor nanoparticles E, 4.12 mg of semiconductor nanoparticles E _G of 0.75mg and green light-emitting semiconductor nanoparticles E _R of the red were prepared by adjusting the particle size so as to emit red light and green light emitting It was dispersed in toluene solvent, further perhydropolysilazane: was added (abbreviation PHPS, Aquamica NN120-10, no catalyst type, AZ Electronic Materials Co., Ltd.), the mass content of the semiconductor nanoparticle _{E R} and _{E G} A coating solution 1 for forming a semiconductor nanoparticle layer was prepared under the condition that the rate was 1.0%.

The above-mentioned coating solution 1 for forming a semiconductor nanoparticle layer has a dry film thickness of 100 μm on a 125 μm-thick polyethylene terephthalate film (KDL86WA, abbreviated as PET: manufactured by Teijin DuPont Films, Ltd.) with easy adhesion processing on both sides. It apply | coated on conditions and dried for 3 minutes at 60 degreeC. Next, excimer irradiation was performed by the following excimer apparatus to produce the optical film 1 of the present invention.

<Excimer irradiation system>
Apparatus: Ex-dimer irradiation apparatus manufactured by M.D.Com Co., Ltd. MODEL: MECL-M-1-200
Irradiation wavelength: 172 nm
Lamp filled gas: Xe
<Reforming treatment conditions>
The film coated with the coating solution 1 for forming a semiconductor nanoparticle layer fixed on the operation stage was subjected to a modification treatment under the following conditions.

Excimer lamp light intensity: 130 mW / cm ² (172 nm)
Distance between sample and light source: 1mm
Stage heating temperature: 70 ° C
Oxygen concentration in the irradiation device: 0.01%
Excimer lamp irradiation time: 5 seconds.

[Preparation of optical films 2 to 6]
Optical films 2 to 6 of the present invention were produced in the same manner as the production of the optical film 1 except that the semiconductor nanoparticles E were changed to the respective semiconductor nanoparticles shown in Table 1.

[Production of optical films 7 and 8]
The optical films 7 and 8 of the present invention were prepared in the same manner as the optical film 1 except that the semiconductor nanoparticles E were changed to the semiconductor nanoparticles shown in Table 1 and no excimer irradiation was performed.

[Preparation of optical films 9 to 11]
Optical films 9 to 11 of comparative examples were produced in the same manner as in the production of the optical film 1 except that the semiconductor nanoparticles E were changed to the respective semiconductor nanoparticles shown in Table 1.

[Preparation of optical film 12]
The 4.12mg of 0.75mg and green light-emitting semiconductor nanoparticles E _G of the semiconductor nanoparticles emitting red light prepared by adjusting the particle diameter E _R to emit semiconductor nanoparticles E in red and green, toluene solvent Further, a photopolymerization initiator Irgacure 184 (manufactured by BASF Japan) is added to UV curing resin Unidic V-4025 manufactured by DIC Corporation in a solid content ratio (mass%) of resin / initiator: 95 / The UV curable resin solution adjusted to 5 was added to prepare a coating solution 12 for forming a semiconductor nanoparticle layer in which the mass content of the semiconductor nanoparticles was 1.0%.

The semiconductor nanoparticle layer forming coating solution 12 was applied to a 125 μm-thick polyethylene terephthalate film (KDL86WA, manufactured by Teijin DuPont Films, Ltd.) with easy adhesion on both sides so that the dry film thickness was 100 μm. The film was dried at 3 ° C. for 3 minutes and cured under a curing condition: 0.5 J / cm ² air using a high-pressure mercury lamp to produce an optical film 12 of a comparative example.

[Preparation of optical films 13 to 16]
Optical films 13 to 16 of comparative examples were produced in the same manner as the production of the optical film 12 except that the semiconductor nanoparticles E were changed to the respective semiconductor nanoparticles shown in Table 1.

[Preparation of optical film 17]
An optical film 17 of the present invention was prepared in the same manner as the optical film 5 except that the substrate was changed to a polycarbonate film having a thickness of 100 μm (manufactured by Teijin Chemicals Ltd., Pure Ace WR-S5, abbreviated as PC). .

[Preparation of optical film 18]
The optical film 18 of the present invention was produced in the same manner as the production of the optical film 5 except that the substrate was changed to a triacetyl cellulose film having a thickness of 100 μm (manufactured by Konica Minolta, abbreviation: TAC).

[Preparation of optical film 19]
An optical film 19 of the present invention was produced in the same manner as the production of the optical film 5 except that the base material was changed to a cycloolefin polymer film having a thickness of 100 μm (manufactured by Nippon Zeon Co., Ltd., abbreviation: COP).

[Preparation of optical film 20]
The particle size was adjusted so that the semiconductor nanoparticles E emitted red and green light. The 0.75mg of semiconductor nanoparticles _{E R} of the red light emitting dispersed in toluene solvent, by adding further perhydropolysilazane (PHPS, Aquamica NN120-10, manufactured by non-catalytic type, AZ Electronic Materials Co.), semiconductor nano A red semiconductor nanoparticle layer forming coating solution R having a particle mass content of 1.0% was prepared.

Then, a 4.12mg of semiconductor nanoparticles _{E G} green light is dispersed in toluene solvent, by adding further perhydropolysilazane (PHPS, Aquamica NN120-10, manufactured by non-catalytic type, AZ Electronic Materials Co.) A coating solution G for forming a green semiconductor nanoparticle layer in which the mass content of the semiconductor nanoparticles was 1.0% was prepared.

Next, the prepared red light emitting semiconductor nanoparticle layer forming coating solution R is applied to a 125 μm thick polyethylene terephthalate film (KDL86WA, manufactured by Teijin DuPont Films, Ltd.) with easy adhesion on both sides, and the dry film thickness is 100 μm. The coating was carried out under the following conditions and dried at 60 ° C. for 3 minutes. Next, excimer irradiation was performed with the following excimer apparatus.

Next, the green light emitting semiconductor nanoparticle layer forming coating solution G was applied on the red light emitting semiconductor nanoparticle layer R under the condition that the dry film thickness was 100 μm, and dried at 60 ° C. for 3 minutes. Next, excimer irradiation was performed with the following excimer apparatus to produce an optical film 20 of the present invention having a semiconductor nanoparticle layer having a two-layer structure of red light emission / green light emission.

[Production of optical film 21]
An optical film 21 was prepared in the same manner as the optical film 3 except that the semiconductor nanoparticles G were changed to the semiconductor nanoparticles L shown in Table 1.

[Preparation of optical film 22]
An optical film 22 was prepared in the same manner as the optical film 4 except that the semiconductor nanoparticles H were changed to the semiconductor nanoparticles M shown in Table 1.

The details of the constituent materials used in the production of the optical films 1 to 22 described in Table 1 and described in abbreviations are as follows.

(material)
PET: Polyethylene terephthalate film PC: Polycarbonate film TAC: Triacetylcellulose film COP: Cycloolefin polymer film (Coating material for semiconductor nanoparticles)
PVA: Polyvinyl alcohol (water-soluble resin)
PMMA: Polymethylmethacrylate (acrylic resin)
PMMA: Polylauryl methacrylate (acrylic resin)
(Dispersion retention material)
PHPS: Perhydropolysilazane UV polymer: UV curable resin (Modification after coating)
VUV: Vacuum ultraviolet irradiation (excimer irradiation)
UV: UV irradiation (high pressure mercury lamp)
<< Evaluation of optical film >>
The following evaluations were performed on the optical films 1 to 22 produced as described above.

[Evaluation of transparency: measurement of haze]
Using the haze meter NDH5000 manufactured by Tokyo Denshoku Co., Ltd., the haze values of the optical films 1 to 22 prepared above were measured, and the transparency was evaluated according to the following criteria.

The optical film is preferably less than 1.5% (◎ to ○ △) from the viewpoint of use in a light emitting device.

A: Haze value is less than 0.5% B: Haze value is 0.5% or more and less than 1.0% B: Haze value is 1.0% or more and less than 1.5% Δ: The haze value is 1.5% or more and less than 3.0%. ×: The haze value is 3.0% or more. [Evaluation of Luminescence Characteristics]
When the optical films 1 to 22 were excited with 405 nm blue-violet light, the luminous efficiency of white light emission at a color temperature of 7000 K was measured. For the measurement, a light emission measurement system MCPD-7000 manufactured by Otsuka Electronics Co., Ltd. was used. For each of the obtained results, the relative luminous efficiency was obtained when the luminous efficiency of the optical film 16 as a comparative example was set to 100, and the luminous characteristics were evaluated according to the following criteria.

A: Relative luminous efficiency is 125 or more. O: Relative luminous efficiency is 115 or more and less than 125. O: Relative luminous efficiency is 105 or more and less than 115. Δ: Relative luminous efficiency is 95 or more. Δ: Less than 105 Δ: Relative luminous efficiency is 85 or more and less than 95 ×: Relative luminous efficiency is less than 85 [Durability Evaluation]
Each optical film produced was subjected to an accelerated deterioration treatment for 3000 hours in an environment of 85 ° C. and 85% RH, and then the light emission efficiency was measured by the same method as the evaluation of the light emission characteristics. The ratio of the luminous efficiency after the accelerated deterioration process to the luminous efficiency (the luminous efficiency after the accelerated deterioration process / the luminous efficiency before the accelerated deterioration process) was determined, and the durability was evaluated according to the following criteria.

○: The value of the luminous efficiency ratio before and after the accelerated deterioration treatment is 0.95 or more. ○ Δ: The value of the luminous efficiency ratio before and after the accelerated deterioration treatment is 0.90 or more and less than 0.95. Δ: The ratio value of the luminous efficiency before and after the accelerated deterioration process is 0.80 or more and less than 0.90. Δ ×: The ratio value of the luminous efficiency before and after the accelerated deterioration process is 0.50 or more, 0. Less than .80 ×: The value of the ratio of the luminous efficiency before and after the accelerated deterioration treatment is less than 0.50. Table 1 shows the evaluation results obtained as described above.

 

As is clear from the results shown in Table 1, it can be seen that the optical film of the present invention is higher in transparency and superior in luminous efficiency and durability than the comparative example.

Example 2
<Production of light emitting device>
The optical films 1 to 22 produced in Example 1 were provided in the light emitting device shown in FIG. 2 to produce the light emitting devices 1 to 22.

Specifically, as shown in FIG. 2, each optical film 4 was pasted on the light emitting surface 5 a of the light guide 5.

<Evaluation of light emitting device>
Each of the produced light-emitting devices was allowed to stand for 3000 hours in an environment of 85 ° C. and 85% RH, and the light emission efficiency was measured. It was confirmed that the rate of change was small and the durability was excellent.

The optical film of the present invention is excellent in luminous efficiency and has excellent durability capable of suppressing deterioration of semiconductor nanoparticles due to oxygen or the like over a long period of time, and high transparency. It can be suitably used as an optical film for various light emitting devices such as space illumination and electroluminescent displays.

DESCRIPTION OF SYMBOLS 1 Light emitting device 2 Image display panel 3 Light source (primary light source)
4 Optical film 5 Light guide 5a Light emission surface 5b Light incident surface 6 Color filter unit 6B, 6G, 6R Color filter 7 Image display layer

Claims (7)

1. An optical film having a substrate and a semiconductor nanoparticle layer provided on the substrate,
   The optical film, wherein the semiconductor nanoparticle layer contains at least one selected from semiconductor nanoparticles coated with a resin, polysilazane and a polysilazane modified body that disperses and holds the semiconductor nanoparticles.
2. The semiconductor nanoparticle layer contains the polysilazane modified body, and the polysilazane modified body is formed by irradiating the polysilazane with vacuum ultraviolet rays, and at least one selected from silicon oxide, silicon nitride, and silicon oxynitride The optical film according to claim 1, which is a compound containing the optical film.
3. The optical film according to claim 1, wherein the semiconductor nanoparticles have a core-shell structure.
4. 4. The optical film according to any one of claims 1 to 3, wherein the resin is an ultraviolet curable resin.
5. 4. The optical film according to any one of claims 1 to 3, wherein the resin is a water-soluble resin.
6. 6. The semiconductor nanoparticle layer comprising two or more semiconductor nanoparticle layers, wherein the two or more semiconductor nanoparticle layers contain semiconductor nanoparticles each having a different emission wavelength. The optical film as described in any one of the above.
7. A light-emitting device comprising the optical film according to any one of claims 1 to 6.

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