WO2008029775A1

WO2008029775A1 - Color conversion substrate

Info

Publication number: WO2008029775A1
Application number: PCT/JP2007/067158
Authority: WO
Inventors: Takashi Sekiya
Original assignee: Idemitsu Kosan Co., Ltd.
Priority date: 2006-09-05
Filing date: 2007-09-04
Publication date: 2008-03-13

Abstract

A color conversion substrate is provided with a color conversion medium containing at least organic nano-crystal light emitting fine particles, and a color filter which is provided with a 70nm or wider transmissive region having a transmissivity of 0.5 or more on one side of the color conversion medium. The light absorbance of the color conversion medium is 0.1 or more but not more than 2, at a wavelength of a transmissive region end on a short wavelength side where the transmissivity of the color filter is 0.5.

Description

Specification

Color conversion board

Technical field

[0001] The present invention relates to a color conversion substrate. For example, the present invention relates to a color conversion substrate that can form an organic electoluminescence color light emitting device in combination with an organic electroluminescence device. More specifically, the present invention relates to a color conversion substrate in which a color conversion medium containing nanocrystal luminescent fine particles and a color filter having a transmission band width of 70 nm or more with a transmittance of 0.5 or more are combined.

Background art

A color conversion medium that converts the wavelength of light emitted from a light source using a fluorescent material has been applied to various fields including the electronic display field. For example, an organic electroluminescent material that emits blue light or blue-green light (hereinafter, the electroluminescent material may be referred to as EL), and absorbs the light emitted from the light emitting layer, and at least one visible color from blue-green to red is visible. An EL element in which a fluorescent material part that emits photofluorescence is disposed is disclosed (for example, see Patent Document 1).

[0003] According to this method, a blue light source is used and color conversion is performed with a color conversion medium to obtain three primary colors. That is, in the color conversion medium, blue light is irradiated to excite the fluorescent dye to generate longer wavelength green light or red light.

Conventionally, organic fluorescent dyes and organic fluorescent pigments have been commonly used as fluorescent materials for color conversion media. For example, a red color comprising a rhodamine fluorescent pigment and a fluorescent pigment having absorption in the blue region and inducing energy transfer or reabsorption to the rhodamine fluorescent pigment dispersed in a light-transmitting medium. A conversion medium is disclosed (see, for example, Patent Document 2).

[0004] As a method for improving the color purity of an EL element using a color conversion medium and improving the contrast ratio in the presence of external light, a technique using a color conversion medium in combination with a color filter has been disclosed ( Patent Document 3).

In order to improve the green performance, the peak wavelength of transmittance is in the range of 490 to 530 nm. It has been proposed to use a phthalocyanine dye as the element! /, (Patent Document 4).

Furthermore, in order to improve color purity, a technique is disclosed in which the absorbance at a wavelength of 450 to 500 nm is 1 or more and the absorbance at 550 to 650 nm is 0.1 or more (Patent Document 5).

[0005] However, Patent Document 15 described above is a technique using an organic fluorescent dye or pigment as a fluorescence conversion material.

In this case, there was a problem of the conversion efficiency deterioration due to the limit of conversion efficiency due to concentration quenching and the thermal chemical reaction history in the manufacturing process. In addition, since the emission band of the organic fluorescent material has a wide emission band, in order to improve the color purity, it was necessary to cut off some of the fluorescence using a narrow band of power filter. Therefore, the energy of fluorescence was lost and the efficiency of the device was lowered! /.

[0006] In order to solve these problems, Patent Document 6 proposes a full-color technology for organic EL elements using inorganic nanocrystals. A film in which CdS, CdSe, and CdTe are dispersed in a light-transmitting resin as an inorganic nanocrystal is used as a color conversion medium, and combined with an organic EL device that emits blue monochromatic light with a peak wavelength of 450 nm. Yes. The conversion colors such as red and green are controlled by controlling the particle size of inorganic nanocrystals.

[0007] Patent Document 7 discloses a color light emitting device that combines an organic EL light source unit and a color conversion medium in which inorganic nanocrystals are dispersed to achieve high fluorescence conversion efficiency and high durability. Considering the high refractive index of inorganic nanocrystals, the color conversion medium is optimally designed to maximize the conversion efficiency.

[0008] In the techniques described in Patent Documents 6 and 7, by using inorganic nanocrystals as fluorescence conversion materials, conversion efficiency limits due to concentration quenching, and conversion performance deterioration due to thermal chemical reaction history in the manufacturing process The problem is solved. However, when inorganic nanocrystals, especially semiconductor nanocrystals, have strong absorption and excitation near the emission peak wavelength, even if a color filter is used in combination, the organic nanocrystal is affected by external light that passes through the color filter. Is excited, and fluorescence is emitted, which causes a reduction in contrast ratio.

Patent Document 1: Japanese Patent Laid-Open No. 3-152897 Patent Document 2: JP-A-8-286603

Patent Document 3: Patent No. 2838064

Patent Document 4: Japanese Patent Laid-Open No. 2000-3786

Patent Document 5: Japanese Patent Application Laid-Open No. 2001_52866

Patent Document 6: U.S. Pat.No. 6,608,439

Patent Document 7: WO2005 / 097939 Nonfret

[0009] The present invention has been made in view of the above problems, and provides a color conversion substrate using inorganic nanocrystals and having an improved contrast ratio in the presence of external light. With the goal.

Disclosure of the invention

[0010] According to the present invention, the following color conversion substrate is provided.

1. a color conversion medium comprising at least inorganic nanocrystal light-emitting fine particles, and a color filter having a transmission band width of 70 nm or more with a transmittance of 0.5 or more on one side of the color conversion medium. The color conversion substrate in which the absorbance of the color conversion medium is 0.1 or more and 2 or less at the wavelength of the short wavelength side transmission band where the transmittance of the color filter is 0.5

Yes

2. The color conversion substrate according to 1, wherein the color conversion medium comprises a transparent medium and inorganic nanocrystal light emitting fine particles dispersed in the transparent medium.

3. The color conversion substrate according to 1 or 2, wherein the inorganic nanocrystal luminescent particle force S is a semiconductor nanocrystal.

4. The color conversion substrate according to any one of [1] to [3], wherein a transmission band width of the color filter is 70 nm or more and 120 nm or less.

5. The color conversion substrate according to any one of 1 to 3, wherein a transmission band width of the color filter is 80 nm or more and lOnm or less.

6. The color conversion substrate according to any one of 1 to 5, which is a green color conversion substrate having an emission peak wavelength in the range of 470 to 550 nm.

7. A color color conversion board, wherein the at least one color pixel includes the color conversion board according to any one of! [[00001111]] According to the present invention, the conversion efficiency efficiency is very high and the high contrast contrast is achieved in the presence of external light. The color and color conversion substrate board that can be produced in actual realization can be provided. . The color-to-color conversion substrate board here is suitable for the organic EELL Kakarara light emitting / emitting device, and it is used for the light emitting / emitting device using this. Then, it becomes possible to increase power saving and power saving. .

Simple and simple explanation on the drawing

[[00001122]] [[FIG. 11]] is a schematic, schematic cross-sectional view of a color-color conversion substrate board according to an embodiment 11 of the present invention. There is. .

[[Fig. 22]] Emission spectrum of the fluorescent lamp used in the calculation, and spectroscopic spectrophotometry of the color-change conversion medium This is the spectral transmittance of Torulu, and the hypothetical Kakararafirru Rata. .

[[Figure 33]] The calculated anti-reflective reflected light outer lure. .

[[FIG. 44]] FIG. 44 is a diagram showing a transmission and overband region of a Kakaralar filter used in calculation. .

[[Fig. 55]] Anti-reflection reflected light intensity, constant contrast index index and variable conversion efficiency rate, and transmission band of Kakaralar filter filter Bandwidth width

[[Fig.66]] Intensity of anti-reflective reflected light, index of contrast finger index and conversion conversion efficiency, and absorption / absorption absorbance of color-change conversion medium FIG. 7] is a schematic cross-sectional view of a color color conversion substrate according to Embodiment 2 of the present invention.

8] It is a schematic cross-sectional view of an organic EL color light emitting device combining a color color conversion substrate and an organic EL element.

[Fig. 9] Transmittance spectrum of color filter CF;! To CF4.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is a schematic cross-sectional view of a color conversion substrate according to Embodiment 1 of the present invention.

The color conversion substrate 1 has a structure in which a color filter 12 and a color conversion medium 13 are laminated on a base material 11 in this order.

The base material 11 supports the color filter 12 and the like, and those used in this field such as a transparent glass substrate and resin substrate can be used without any problem.

The color filter 12 has a function of adjusting the emission color to a desired color. In addition, the color conversion medium emits fluorescence by light incident from the outside of the light emitting device, such as sunlight or indoor illumination light, or the incident light is reflected by the reflective electrode and re-emitted, so that the contrast ratio, The ratio of the brightness when the light-emitting device is in the light-emitting state and in the non-light-emitting state is prevented from decreasing. Stop.

The color conversion medium 13 is a film in which luminous particles 13b are dispersed in a transparent medium 13a, which absorbs excitation light emitted from a light source (not shown) and emits light having a spectrum different from that of the light source (fluorescence). To emit.

[0014] In the present invention, the color conversion medium contains nanocrystal luminescent fine particles, and the width of the transmission band where the transmittance of the power filter is 0.5 or more is 70 nm or more. By adopting such a configuration, the color conversion substrate can achieve high power consumption with high efficiency and high contrast in the presence of external light.

In this specification, the transmission band means a wavelength range where the light transmittance of the color filter is 0.5 (50%) or more, and the width of the transmission band means that the transmittance of the color filter is 0.5. It means the width between two wavelengths (short wavelength end and long wavelength end). The transmission band of the color filter can be obtained by measuring the transmittance of the color filter using an ultraviolet-visible spectrophotometer and measuring the wavelength region where the transmittance is 0.5 or more.

[0015] In general, a color filter having a narrow transmission band is used to cut outside light and improve the contrast ratio. Specifically, a transmission band having a width of about 60 to 70 nm is used. However, the present inventor has found that a unique performance can be exhibited by combining a color filter having a wide transmission band with a color conversion medium using inorganic nanocrystals.

[0016] Fig. 2 shows the emission spectrum of a fluorescent lamp that is external light, the absorbance spectrum of a color conversion medium (green, CdSe / ZnS core-shell semiconductor nanocrystal, emission peak wavelength 525 nm, emission half-value width 30 nm), and The transmission spectrum of a virtual color filter (transmission characteristics are parabolic, and the transmission band width of transmittance 0.5 or more is 70 nm).

FIG. 3 shows a reflected light spectrum calculated from these.

In order to consider reflection, the reflectance of the organic EL element (light source) combined with the color conversion substrate was set to 0.8. The spectrum of the reflected light was calculated as follows.

[0017] The external light is filtered by the set color filter and then enters the color conversion medium. This light is propagated toward the light source while being absorbed by the color conversion medium, reflected by the light source, and then passes through the color conversion medium while being absorbed again. The light is transmitted through the color filter. On the other hand, the light absorbed by the color conversion medium re-emits longer wavelengths with a certain fluorescence quantum yield (assuming 0.8). The re-emitted light propagates toward the color filter and the light source unit while being reabsorbed by the color conversion medium. The light directed to the color filter passes through the color filter and is emitted. The light directed to the light source unit reaches the light source unit while being absorbed by the color conversion medium, is reflected, passes through the color conversion medium again, passes through the color filter, and exits. Considering the above process, the reflected light vector was calculated.

[0018] The reflected light includes a re-emission component of the semiconductor nanocrystal in addition to the reflection component of the external light passing through the color filter. A unique characteristic of using inorganic nanocrystals is that reflected light is strongly suppressed on the short wavelength side of the transmission band of the color filter. This is due to the absorption by the absorption edge of inorganic nanocrystals (absorption maximum near 500 nm), and almost all external light is absorbed.

FIG. 4 shows the transmission band of the color filter used in the calculation. In this manner, the performance as a color conversion substrate was calculated by changing the width of the transmission band from 40 to OOnm.

[0020] The reflected light luminance is the luminance of light emitted by external light (the sum of the reflected light and the re-emission component: arbitrary unit). The conversion efficiency is estimated based on the performance of the color conversion substrate assuming that a bottom emission type organic EL device with a peak emission wavelength of 470 nm is used as the light source. The conversion efficiency is the ratio of the brightness of the outgoing converted light to the brightness of the incident organic EL element light, and its unit is%. That is, this conversion efficiency may be considered to represent the light emission luminance when a constant power is applied. Therefore, the value obtained by dividing the conversion efficiency by the reflected light luminance represents the contrast ratio, so this value was scaled appropriately to obtain the contrast index [arbitrary unit].

FIG. 5 is a graph showing the relationship between the reflected light intensity, the contrast index and the conversion efficiency, and the width of the transmission band of the color filter.

The results in Figure 5 are contrary to expectations, indicating that increasing the width of the color filter transmission band improves the contrast ratio. This is because if the width of the transmission band is increased, light emitted from the color conversion medium can be extracted sufficiently. At this time, the reflection of external light on the short wavelength side of the transmission band is also increased as the fluorescent component from the color conversion medium excited by external light increases. Constrained by the unique absorption of the inorganic nanocrystals, the increase in the emission of the element exceeds the increase in the output light as a whole, so the contrast is improved.

[0022] From the above results, as a region in which the conversion efficiency and contrast ratio of the color conversion substrate are compatible, a transmission band width of 7 Onm or more is preferable, and 70 nm to 120 nm is particularly preferable. Especially 80nm or more and 1 lOnm or less is preferred!

[0023] In particular, the color conversion substrate of the present invention can be preferably used as a green color conversion substrate having an emission peak wavelength in the range of 470 to 550 nm.

In the present invention, the absorbance of the color conversion medium is 0.1 or more and 2 or less at the wavelength at the end of the transmission band on the short wavelength side where the transmittance of the color filter is 0.5.

The absorbance of the color conversion medium can be obtained as follows using a general ultraviolet-visible spectrophotometer.

First, the transmitted light intensity I at the wavelength of an uncoated substrate on which no color conversion medium is formed is calculated.

0 Measure.

Next, the substrate on which the color conversion medium is formed is placed, and the transmitted light intensity I is measured. At this time, the absorbance A at the wavelength is obtained by A = log (I / 1).

10 0

[0025] As described above, absorption of inorganic nanocrystals is important in the present invention. Therefore, by changing the concentration of inorganic nanocrystals, the reflected light brightness, conversion efficiency, and contrast index for the absorbance at the transmission band edge of the color filter (510 nm for the short wavelength side, transmission band 70ηm color filter). Was calculated.

Fig. 6 shows the relationship between reflected light intensity, contrast index, and conversion efficiency, and the absorbance of the color conversion medium. From this, the absorbance of the color conversion medium is 0.;! ~ 2, and 0.2 ~ 2 is particularly preferable. I know that there is. If it is smaller than 0.1, neither the light emission brightness nor the contrast ratio may be sufficient. If it is greater than 2, it indicates that the concentration of inorganic nanocrystals is very high, and the dispersibility in a transparent medium may be impaired.

Embodiment 2

FIG. 7 is a schematic cross-sectional view of a color color conversion substrate according to Embodiment 2 of the present invention.

The color color conversion substrate 2 uses the color conversion substrate of the first embodiment. Color change The replacement substrate 2 includes a blue color filter 21B, a green color filter 21G and a green color conversion medium 22G stack, and a red color filter 21R and a red color conversion medium 22R stack.

In the color color conversion substrate 2, a blue pixel B is formed by a light source (not shown) and a blue color filter 21B. Similarly, the stacked body of the light source, the green color filter 21G and the green conversion medium 22G forms a green pixel G, and the stacked body of the light source, the red color filter 21R and the red conversion medium 22R forms a red pixel R. As shown in FIG. 7, a black matrix 23 may be formed between the pixels.

Full-color display is possible by independently driving the light source corresponding to each pixel by a known method.

In the present embodiment, it is possible to suitably use the color conversion substrate of Embodiment 1 particularly in a green pixel. For the blue pixel and the red pixel, for example, the configuration of Patent Document 7 described above can be suitably used.

FIG. 8 is a schematic cross-sectional view of an organic EL color light emitting device in which a color color conversion substrate and an organic EL element are combined.

The organic EL color light emitting device 3 has a configuration in which an organic EL element 30 serving as a light source and a color color conversion substrate 2 are stacked with a transparent medium 40 interposed therebetween.

As the organic EL element, for example, those exemplified in Patent Document 7 can be used.

[0030] As the transparent medium, an organic material, an organic material, a laminate thereof, and the like can be appropriately used as long as the transparent medium has a transmittance of visible light of 50% or more.

Among inorganic materials, inorganic oxide layers, inorganic nitride layers, and inorganic oxynitride layers are preferable. Examples include silica, alumina, AION, SiAlON, SiNx (l≤x≤2), SiOxNy (preferably 0.l≤x≤l, 0.l≤y≤l).

As the organic material, silicone gel, fluorinated hydrocarbon liquid, acrylic resin, epoxy resin, silicone resin, or the like can be used.

In the case of an inorganic material, the transparent medium can be formed by a sputtering method, a CVD method, a sol-gel method, or the like. In the case of organic materials, the spin coating method, printing method, dripping method, etc. can be used. The layer thickness of the transparent medium is preferably 0 · Ol ^ m-lOmm, more preferably 0.l ^ umlmm.

[0031] Each component forming the color conversion member of the present invention will be described below.

[Color conversion media]

(1) Luminescent fine particles

The luminescent fine particles used in the present invention are composed of inorganic nanocrystals in which inorganic crystals are made ultrafine to the nanometer order. As the inorganic nanocrystal, a material that absorbs visible and / or near-ultraviolet light and emits visible fluorescence is used. Since the transparency is high and the scattering loss is small, it is preferable to use inorganic nanocrystals with ultrafine particles having a particle size of 20 nm or less, more preferably 10 nm or less.

When the transparent medium described later is a resin, the surface of the inorganic nanocrystal is preferably subjected to a compatibilizing treatment in order to improve dispersibility in the resin. Examples of the compatibilizing treatment include a treatment such as modifying or coating the surface with a long-chain alkyl group, phosphoric acid, resin or the like.

[0032] Specific examples of the inorganic nanocrystal used in the present invention include the following.

(1 a) Nanocrystal phosphor with metal oxide doped with transition metal ions

Nano crystal phosphors doped with transition metal ions in metal oxides include Y O, G

2 3 d O, ZnO, Y Al O, ZnSiO, etc., Eu ²⁺ , Eu ³⁺ , Ce ³⁺ , Tb ³⁺ etc.

2 3 3 5 12 2 4

And those doped with transition metal ions that absorb visible light.

(1 b) Nanocrystal phosphor in which metal chalcogenide is doped with transition metal ions As nanocrystal phosphor in which metal chalcogenide is doped with transition metal ions,

Metal chalcogenides such as ZnS, CdS, and CdSe doped with transition metal ions that absorb visible light, such as Eu ²⁺ , Eu ³⁺ , Ce ³⁺ , and Tb ³⁺ . In order to prevent S and Se from being pulled out by the reaction components of the matrix resin described later, the surface may be modified with a metal oxide such as silica or an organic substance.

[0034] (1 c) Nanocrystal phosphor (semiconductor nanocrystal) that absorbs and emits visible light using the semiconductor band gap

The semiconductor nano-kustal materials include group IV elements, group Ila elements VI group elements, group Ilia elements, group Vb elements, and group Illb elements, group Vb elements in the long-period periodic table. The compound and the crystal | crystallization which consists of a chalcopyrite type compound can be mentioned.

[0035] Concrete Hakuho (Ma, Si, Ge, MgS, MgSe, ZnS, ZnSe, ZnTe, A1P, AlAs, AlSb, GaP, GaAs, GaSb, CdS, CdSe, CdTe, InP, InAs, InSb, AgAlAs, AgAlSe

twenty two

, AgAlTe, AgGaS, AgGaSe, AgGaTe, AglnS, AglnSe, AglnTe, ZnS

2 2 2 2 2 2 2 iP, ZnSiAs, ZnGeP, ZnGeAs, ZnSnP, ZnSnAs, ZnSnSb, CdSiP, C

2 2 2 2 2 2 2 2 Crystals of dSiAs, CdGeP, CdGeAs, CdSnP, CdSnAs, etc.

2 2 2 2 2

Can include mixed crystal crystals of the compound.

[0036] Preferably, Si, A1P, AlAs, AlSb, GaP, GaAs, InP, ZnSe, ZnTe, CdS, Cd Se, CdTe, CuGaSe, CuGaTe, CuInS, CuInSe, CuInTe, direct transition

2 2 2 2 2

Type semiconductors such as ZnSe, ZnTe, GaAs, CdS, CdTe, InP, CuInS, CuInSe

2 2 The luminous efficiency is high, and it is more preferable in terms of points.

[0037] Among the inorganic nanocrystals, the emission wavelength can be easily controlled by the particle size, and has a large absorption in the blue wavelength range and the near-ultraviolet wavelength range, and the degree of overlap between absorption and emission in the emission range is large. Preferably, a semiconductor nanocrystal is used.

[0038] The function of the semiconductor nanocrystal will be described below.

As known in documents such as JP 2002-510866, these semiconductor materials are bandages of 0.5 to 4. OeV at room temperature for Balta materials (meaning non-particulate materials). Has a gap. By forming fine particles with these materials and making the particle size nanosized, electrons in the semiconductor are confined in the nanocrystal. As a result, the band gap in the nanocrystal increases.

[0039] It is known that the width in which the band gap increases is theoretically inversely proportional to the square of the particle diameter of the semiconductor fine particles. Therefore, it is possible to control the band gap by controlling the particle size of the semiconductor particles. These semiconductors absorb light having a wavelength shorter than the wavelength corresponding to the band gap, and emit fluorescence having a wavelength corresponding to the band gap.

[0040] The band gap of the Balta semiconductor is preferably 1.0 eV to 3. OeV at 20 ° C. 1. Below OeV, when nanocrystallized, the fluorescence wavelength shifts too sensitively to changes in particle size, which is not preferable in terms of difficulty in production control. Also, when it exceeds 3. OeV, it emits only fluorescence with a wavelength shorter than the near ultraviolet region, and it can be applied as a color light emitting device. If it ’s difficult, it ’s a good point.

[0041] The semiconductor nanocrystal can be produced by a known method, for example, a method described in US Pat. No. 6,501,091. As a production example described in this publication, trioctylphosphine oxide (TOPO) obtained by heating a precursor solution in which trioctylphosphine (TOP) is mixed with trioctylphosphine selenide and dimethylcadmium to 350 ° C is used. ).

[0042] The semiconductor nanocrystal preferably includes a core particle made of a semiconductor nanocrystal, and a core layer made of a semiconductor material having a band gap larger than that of the semiconductor material used for the core particle. 'Shell-type semiconductor nanocrystal. This has a structure in which, for example, the surface of a core fine particle made of CdSe (band gap: 1.74 eV) is coated with a shell of a semiconductor material having a large band gap, such as ZnS (node gap: 3.8 eV). This facilitates the confinement effect of excitons generated in the core fine particles. In the specific examples of semiconductor nanocrystals described above, S, Se, etc. are pulled out by the active components (unreacted monomers, moisture, etc.) in the transparent medium described later, the crystal structure of the nanocrystals is broken, and the fluorescence disappears It is easy to happen. In order to prevent this, the surface may be modified with a metal oxide such as silica or an organic substance.

[0043] The core-shell type semiconductor nanocrystal can be produced by a known method, for example, the method described in US Pat. No. 6,501,091. For example, in the case of a CdSe core / ZnS shell structure, it can be produced by introducing a precursor solution in which jethyl zinc and trimethylsilyl sulfide are mixed with TOP into a TOPO liquid in which CdSe core particles are dispersed and heated to 140 ° C.

[0044] Also, the carrier forming excitons is separated between the core and the shell, so-called Type

Type II nanocrystallinole (J. Am. Chem. Soc., Vol. 125, No. 38, 2003, pl l466-l

1467) can also be used.

In addition, a nanocrystal (Angewandte Chemie, Vol. 2) with a multi-shell structure by laminating two or more layers on the core to improve stability, light emission efficiency, and emission wavelength adjustment.

115, 2003, p5189- 5193) even when the ffllヽJ: Rere ₀

[0045] The above light-emitting fine particles may be used alone or in combination of two or more. May be used.

Particularly suitable in the present invention are inorganic light-emitting fine particles having an emission peak wavelength of fluorescence of 470 to 550 nm, and the ability S to obtain good results in combination with a color filter described later.

[0046] (2) Transparent medium

The transparent medium is a medium for dispersing and holding inorganic nanocrystals, and a transparent material such as glass or transparent resin can be selected. In particular, from the viewpoint of workability of the color conversion medium, a resin such as a non-curable resin, a thermosetting resin, or a photocurable resin is preferably used.

Specifically, oligomeric or polymeric melamine resin, phenolic resin, alkyd resin, epoxy resin, polyurethane resin, maleic acid resin, polyamide resin, polymethylol methacrylate, polyacrylate, polycarbonate, polybulualcohol, Examples thereof include polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, and the like, and copolymers having monomers forming them as constituent components.

[0047] For the purpose of patterning the color conversion medium, a photocurable resin can be used. As the photocurable resin, a photopolymerization type such as acrylic acid having a reactive bur group or a methacrylic acid-based photopolymerization type or a polycacinic acid bur is generally used. In addition, if it contains no photosensitizer, a thermosetting type may be used!

[0048] In a full color display, a color conversion medium is formed in which phosphor layers separated from each other are arranged in a matrix. For this reason, as the matrix resin (transparent medium), it is preferable to use a photocurable resin to which a photolithography method can be applied.

In addition, as these matrix resins, one kind of resin may be used alone, or a plurality of kinds may be mixed and used.

If no photosensitizer is included, a light-emitting pattern can be formed by printing such as screen printing.

[0049] (3) Production of color conversion medium

The color conversion medium is produced by using a dispersion obtained by mixing and dispersing luminous particles and matrix resin (transparent medium) using a known method such as a mill method or an ultrasonic dispersion method. At this time, a good solvent for the matrix resin can be used. This luminous fine particle dispersion is A color conversion medium is produced by forming a film on a support substrate by a known film formation method, for example, a spin coating method, a screen printing method, or the like.

In addition, in the range which does not impair the object of the present invention, an ultraviolet absorber, a dispersant, a leveling agent and the like may be added to the color conversion medium in addition to the luminescent fine particles and the transparent medium.

[0050] [Color filter]

The color filter adjusts the color of emitted light to a desired color, and the color conversion medium emits fluorescence by light incident from the outside of the light emitting device, such as sunlight or indoor illumination light, or incident light is reflected by the reflective electrode. Thus, by re-emission, it is possible to prevent a reduction in contrast ratio, that is, the specific power of brightness when the light emitting device is in a light emitting state and in a non-light emitting state.

[0051] Examples of the color filter used in the present invention include the following dyes alone or those in a solid state in which a dye is dissolved or dispersed in a binder resin. Red (R) dye: Perylene pigment, lake pigment, azo pigment, etc.

Green (G) dyes: Halogen polysubstituted phthalocyanine pigments, halogen polysubstituted copper phthalocyanine pigments, trifelmethane basic dyes, etc.

Blue (B) dye: Copper phthalocyanine pigment, indanthrone pigment, indophenol pigment, cyanine pigment, etc.

[0052] On the other hand, the binder resin is preferably a transparent material (visible light transmittance of 50% or more). For example, transparent resins (polymers) such as polymethylmethacrylate, polyacrylate, polycarbonate, polybutyl alcohol, polyvinylpyrrolidone, hydroxyethinoresenorelose, canolepoxymethinoresolerose, etc. Examples of the photosensitive resin to which the method can be applied include photocurable resist materials having a reactive bur group such as acrylic acid or methacrylic acid. When the printing method is used, a printing ink (medium) using a transparent resin such as polychlorinated bur resin, melamine resin, or phenol resin is selected.

[0053] When the color filter is mainly composed of a dye, the film is formed by vacuum deposition or sputtering through a mask of a desired color filter pattern. On the other hand, when the color filter is composed of a dye and a binder resin, the fluorescent dye and the above-described dye are formed. Resin and resist are mixed, dispersed, or solubilized, formed into a film by a method such as spin coating, roll coating, or casting, and patterned with a desired color filter pattern by a photolithography method or desired by a method such as printing. Color filter It is common to pattern with this pattern.

[0054] As described above, the color filter of the present invention has a transmission band width of 70 nm or more. The adjustment of the transmission band of the power filter is, for example, a yellow pigment that absorbs light on the short wavelength side and transmits light on the long wavelength side (for example, PY138, manufactured by BASF), short wavelength side, and long wavelength side It can be carried out by appropriately combining with a green pigment having absorption in both (for example, PG7, manufactured by BASF).

[Example]

[0055] Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the following examples unless it exceeds the gist.

[0056] Production Example 1 [Production of light source (organic EL element)]

An organic EL device having the following configuration was fabricated. In addition, the numerical value in Katsuko is a film thickness. The structure of the compound used is shown below.

Device configuration: Glass substrate (0 · 7mm) / ITO (indium tin oxide) (130nm) / HT1 (6 Onm) / HT2 (20nm) / BH: BD ((40: 2) 42nm) / Alq (20nm) / LiF (lnm) / Al (150nm)

[0057] [Chemical 1]

HT 2 HT

A 1 q

[0058] On a glass substrate having a thickness of 0.7 mm, ITO was deposited to a thickness of 130 nm by sputtering. This substrate was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes, followed by UV ozone cleaning for 30 minutes, and then the substrate with the ITO electrode was mounted on the substrate holder of the vacuum deposition apparatus.

[0059] Each of the above materials was mounted on each molybdenum heating boat in advance.

First, an HT1 film that functions as a hole injection layer is formed at a thickness of 60 nm, and then an HT2 film that functions as a hole transport layer is formed at a thickness of 20 nm. As a medium layer, Compound BH and Compound BD were co-deposited at a film thickness of 42 nm so as to have a film thickness ratio of 40: 2. On this film, an Alq film was formed as an electron transport material layer with a thickness of 20 nm, a LiF film was formed as an electron injection layer with a thickness of 1 nm, and then A1 was deposited as a cathode with a thickness of 150 nm to produce an organic EL device.

[0060] A voltage was applied to the device, and the current efficiency and emission color of lOmA / cm- ² of the blue organic EL device were measured with a spectral radiance meter. As a result, current efficiency 7.9cd / A, CIE Blue emission with color coordinates (0.135, 0.198) was obtained.

[0061] Production Example 2 [Preparation of color filter]

As organic pigments for the green color filter, the four types shown in Table 1 were used. An ink was prepared by dissolving these pigments in an Atalinole negative photoresist (V259PA, solid content concentration 50%: manufactured by Nippon Steel Chemical Co., Ltd.). This ink is spin-coated on a glass substrate, exposed to ultraviolet light, developed with a 2% aqueous sodium carbonate solution, and baked at 200 ° C to form a green conversion film pattern (film thickness 1.5 111). did. The formulation of the organic pigment of the ink was prepared, and four kinds of colorinoleta (CF;! To CF4) shown in Table 1 were prepared.

Table 1 shows the pigment composition of the color filter, the film thickness, the width of the transmission band where the transmittance is 50% or more, and the wavelength at the short wavelength end where the transmittance is 50%.

The transmission band and its width were determined by measuring the transmittance spectrum of the color filter with an ultraviolet-visible spectrophotometer. Figure 9 shows the transmittance spectrum of each color filter.

[0062] [Table 1]

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The following materials were used as materials for the color conversion medium.

(a) Luminescent fine particles

As the light-emitting fine particles, a core-shell type semiconductor nanocrystal with a ZnS shell attached to a CdSe core (diameter 3.9 nm) was used. Fluorescence peak wavelength is 525nm, emission half width is 30η m.

(b) Transparent medium solution for dispersing and holding luminescent particles

As the transparent medium, methacrylic acid-methyl methacrylate copolymer (methacrylic acid copolymer spoon ^{_{= 15~20 0/0, Mw =}} 20, 000-25, 000, refractive skewer 1.60) use the Rere, which 1 Dissolved in methoxy-2-acetoxypropane to give a clear medium solution.

[0064] (1) Fabrication of color conversion substrate

The above light-emitting particles, the solids concentration in the film 5. put into 0 X 10- ³ mol / transparent medium solution so that L, and was subjected to dispersion treatment.

This dispersion is formed on the color filter film of the green color filter substrate (CF1) prepared in Production Example 2 by spin coating, dried at 200 ° C for 30 minutes, and converted to a color with a thickness of 20 111 The medium was formed into a film to obtain a color conversion substrate (CCM1).

For evaluation, a color conversion medium was formed on a glass substrate in the same manner as the film formation on the color conversion substrate. The absorption spectrum of this color conversion medium was measured with an ultraviolet-visible spectrophotometer.

[0065] (2) Evaluation

Silicone oil with a refractive index of 1.53 so that the glass substrate side (light extraction side) of the organic EL device produced in Production Example 1 and the color conversion medium layer of the color conversion substrate produced in (1) above face each other. A light-emitting device was obtained by pasting them together.

The light emission luminance (luminance: A [nit]) from the color conversion substrate was measured under the condition that the organic EL device emits light at 150 [nit].

Also, the brightness of reflected light (brightness B [nit]) from the color conversion board under fluorescent lighting (5001x) with the organic EL element turned off is measured, and the contrast ratio is obtained from the ratio (A / B). It was. As a result, the emission luminance when the organic EL element was turned on was 218 nits, the emission luminance when the organic EL element was turned off (under fluorescent lighting) was 0.59 nits, and the contrast ratio was 370. The absorbance of the color conversion medium at the short wavelength end wavelength (480 nm) at which the transmittance of the color filter (CF1) is 50% was 0.571.

Table 2 shows the configuration and evaluation results of the color conversion substrate prepared in Example 1 and each example described later.

[0066] [Table 2]

Example 2

A color conversion substrate was prepared and evaluated in the same manner as in Example 1 except that the color filter (CF2) was used instead of the color filter (CF1).

As a result, the light emission brightness when the organic EL element is on is 210 nits, and the light emission when the organic EL element is off The brightness was 0.57 nit and the contrast ratio was 370, which was good. The absorbance of the color conversion medium at the short wavelength end wavelength (486 nm) at which the transmittance of the color filter (C F2) is 50% was 0.670.

[0068] Example 3

A color conversion substrate was prepared and evaluated in the same manner as in Example 1 except that the color filter (CF3) was used instead of the color filter (CF1).

As a result, the emission brightness when the organic EL element was turned on was 198 nits, the emission brightness when the organic EL element was turned off was 0.57 nits, and the contrast ratio was 350, which was slightly lower than in Examples 1 and 2, but was good. there were. The absorbance of the color conversion medium at the wavelength (503 nm) at the short wavelength end where the transmittance of the color filter (CF3) is 50% was 1.07.

[0069] Comparative Example 1

A color conversion substrate was prepared and evaluated in the same manner as in Example 1 except that the color filter (CF4) was used instead of the color filter (CF1).

As a result, the emission luminance when the organic EL element was turned on decreased to 172 nits, the emission luminance when the organic EL element was turned off was 0.57 nits, and the contrast ratio also decreased to 300. The absorbance of the color conversion medium at the short wavelength end wavelength (522 nm) at which the transmittance of the color filter (CF4) was 50% was 0.728.

[0070] Comparative Example 2

(1) Fabrication of color conversion board

The luminescent particles, solid content concentration in the film 1. put into 0 X 10- ² mol / transparent medium solution so that L, and was subjected to dispersion treatment.

This dispersion was formed on the color filter film of the green color filter substrate (CF2) prepared in Production Example 2 by spin coating, and dried at 200 ° C for 30 minutes. A color conversion medium was formed into a film to obtain a color conversion substrate (CCM2).

[0071] (2) Evaluation

A light emitting device was formed and evaluated in the same manner as in Example 1. As a result, the light emission luminance when the organic EL element was turned on decreased to lOOnit, the light emission luminance when the organic EL element was turned off was 0.48 nit, and the contrast ratio also decreased to 210. The absorbance of the color conversion medium at the short wavelength (486 nm) at which the transmittance of the color filter (CF2) was 50% was 2.68.

[0072] Comparative Example 3

In the preparation of the color conversion substrate, a light-emitting particles, the solids concentration in the film was put in a transparent medium solution so that a ^{5. 0 X 10- 4 mol / L} , except that was distributed processing, similarly to Comparative Example 2 A color conversion substrate (CCM3) was prepared and evaluated.

As a result, the emission luminance when the organic EL element was turned on decreased to 122 nits, the emission luminance when the organic EL element was turned off was 0.64 nits, and the contrast ratio also decreased to 190. The absorbance of the color conversion medium was 0.04 at the short wavelength (486 nm) at which the transmittance of the color filter (CF2) was 50%.

Industrial applicability

[0073] The color conversion substrate of the present invention can be suitably used as a member for forming a light-emitting device in combination with various light sources such as an organic EL element and a light-emitting diode. In particular, it is suitable as a color conversion substrate for organic EL elements.

Claims

The scope of the claims

[1] a color conversion medium comprising at least inorganic nanocrystal luminescent particles;

A color filter having a transmission band width of 70 nm or more on one side of the color conversion medium having a transmittance of 0.5 or more;

A color conversion substrate, wherein the color conversion medium has an absorbance of 0.1 or more and 2 or less at a wavelength at a transmission band edge on a short wavelength side where the transmittance of the color filter is 0.5.

2. The color conversion substrate according to claim 1, wherein the color conversion medium is composed of a transparent medium and inorganic nanocrystal luminescent fine particles dispersed in the transparent medium.

[3] The color conversion substrate according to [1] or [2], wherein the inorganic nanocrystal luminescent fine particle force is a semiconductor nanocrystal.

[4] The transmission band width of the color filter is not less than 70 nm and not more than 120 nm.

3! /, The color conversion board described in the gap.

[5] The transmission band width of the color filter is not less than 80 nm and not more than lOnm.

3! /, The color conversion board described in the gap.

6. The color conversion substrate according to any one of claims 1 to 5, which is a green color conversion substrate having an emission peak wavelength in the range of 470 to 550 nm.

[7] A color color conversion substrate, wherein the at least one color pixel includes the color conversion substrate according to any one of claims;! To 6.