KR20150143258A - Photochromic glass - Google Patents

Abstract

According to an embodiment of the present invention, a photochromic glass comprises: a photochromic layer whose transmittance of visible light is reduced in short-wavelength light and the transmittance of the visible light is increased in long-wavelength light; a short wavelength transmittance layer provided on one surface of the photochromic layer to transmit only the short-wavelength light from the light incident to the photochromic layer; and a wavelength conversion layer provided on the other surface which is opposite to the photochromic layer to convert a wavelength of the light incident to the photochromic layer into a long-wavelength, or a long-wavelength transmittance layer for transmitting only the light of the long-wavelength from the light incident to the photochromic layer. The transmittance of the visible light of the photochromic layer can be controlled through an incident direction of the light to both facing surfaces of the photochromic layer. Accordingly, the photochromic glass can realize various colors according to the photochromic layer, and have a thermal insulation function due to infrared blocking of a short-wavelength transmittance layer.

Description

[0001] PHOTOCHROMIC GLASS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photochromic glass, and more particularly, to a photochromic glass which is switched by irradiation with selective light.

Most of the functional windows used today use electrochromic devices whose transmittance varies with the applied voltage. Since general electrochromic devices use electrolytes, they are difficult to apply to windows and have problems in terms of stability and reaction time. Therefore, it is necessary to develop a photochromic device having a characteristic in which the molecular structure is changed and the transmittance of visible light is reduced when light of a specific wavelength is irradiated. The photochromic layer for photochromic devices is mostly organic and reacts with ultraviolet light to cause photochromism. Recently, organic dyes have been developed that maintain stability at room temperature and maintain a photochromic state before light of a different wavelength is applied.

An object of the present invention is to add a light switching function to a photochromic glass.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

A photochromic glass is provided to solve the above technical problems. A photochromic glass according to an embodiment of the present invention includes a photochromic layer, a short-wavelength transmittance layer disposed on a first surface of the photochromic layer and having a high transmittance to light with a shorter wavelength than a long wavelength, And a wavelength conversion layer disposed on a second surface opposing the surface and converting light of a short wavelength into light of a long wavelength.

For example, when the photochromic layer is irradiated with ultraviolet rays, the absorbance of visible light increases, and when the near infrared rays are irradiated, the transmittance may increase.

For example, the photochromic layer may comprise at least one selected from the group consisting of azobenzene, spiro-naphtoxazine, naphtopyran, spiropyran, furylfulgide, stilbene, ), Nitron, fulgide, triarylmethane, diarylethene, MoO _x , or WO _x .

The short wavelength transmissive layer has a thickness of less than 500 nm and may include a transparent electrode selected from ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ .

The short-wavelength transmissive layer may be a multi-layer thin film of photonic function including an insulator having a thickness of less than 500 nm and an ultra-thin metal. The insulator may be selected from ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ . The ultra-thin metal may be selected from Ag, Cu, Al, Au, Pt, Zn, Cr, and Mo.

The wavelength conversion layer may include an organic dye, a lanthanide inorganic thin film, TiO _x, or ZnO _x .

The photochromic glass according to another embodiment of the present invention comprises a photochromic layer, A short wavelength transmitting layer disposed on the first surface of the photochromic layer and having high transmittance to light having a shorter wavelength than light having a long wavelength and a second wavelength transmitting layer disposed on a second surface opposing the first surface of the photochromic layer, And a long wavelength transmission layer that absorbs and blocks the light.

For example, when the photochromic layer is irradiated with ultraviolet rays, the absorbance of visible light increases, and when the near infrared rays are irradiated, the transmittance may increase.

For example, the photochromic layer may comprise at least one selected from the group consisting of azobenzene, spiro-naphtoxazine, naphtopyran, spiropyran, furylfulgide, stilbene, ), Nitron, fulgide, triarylmethane, diarylethene, MoO _x , or WO _x .

The short wavelength transmissive layer has a thickness of less than 500 nm and may include a transparent electrode selected from ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ .

The short-wavelength transmissive layer may be a multi-layer thin film of photonic function including an insulator having a thickness of less than 500 nm and an ultra-thin metal. The insulator may be selected from ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ . The ultra-thin metal may be selected from Ag, Cu, Al, Au, Pt, Zn, Cr, and Mo.

The long wavelength transmissive layer may include a light absorbing material having a band gap of 1.5 to 2.5 eV. The light absorbing material may include amorphous silicon, microcrystalline silicon, amorphous silicon-germanium, CIGS, CdTe, GaAs, INP, SiC, SiN or SiO.

The long wavelength transmissive layer may further include a dielectric selected from ITO, ZnO: Al, ZnO: Ga, SnO ₂ , ZnO, TiO ₂ , Al ₂ O ₃ , SiO ₂ and ZrO ₂ .

The long wavelength transmissive layer may be an inorganic thin film having a thickness of 20 to 500 nm.

The photochromic glass according to embodiments of the present invention includes a photochromic layer.

Light having a specific wavelength can change the transmittance of the photochromic layer. The wavelength region of the incident component can be controlled by the short wavelength transmission layer, the wavelength conversion layer, and the long wavelength transmission layer. If the wavelength of the incident component is shortened, the visible light transmittance of the photochromic layer becomes low. The incident light having a short wavelength is limited to the short wavelength transmission layer. Further, when the wavelength of the incident component becomes long, the visible light transmittance of the photochromic layer becomes high. The incident long wavelength light is limited to the wavelength converting layer or the long wavelength transmitting layer. Therefore, the transmittance of the photochromic layer can be adjusted according to the incident direction of light.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding and assistance of the invention, reference is made to the following description, taken together with the accompanying drawings,
1 is a graph showing characteristics of a photochromic layer according to embodiments of the present invention.
2 is a cross-sectional view of a photochromic glass according to an embodiment of the present invention.
FIG. 3 is a graph of transmittance change according to wavelength of a short-wavelength transmittance layer according to an embodiment of the present invention.
4 is a graph of wavelength conversion characteristics according to wavelength of a wavelength conversion layer according to an embodiment of the present invention.
5 is a cross-sectional view illustrating a photochromic glass according to another embodiment of the present invention.
6 is a graph of transmittance variation according to wavelength of a long wavelength transmission layer according to another embodiment of the present invention.
7 is a view illustrating the coloring and decoloring principle of the optical switching discoloration sunglass according to the embodiments of the present invention.
8 is a view illustrating the coloring and decoloring principles of an optical switching discoloration window for a building according to embodiments of the present invention.
9 is a view illustrating the coloring and decoloring principles of an optical switching vehicle color fading window according to embodiments of the present invention.

In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It will be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof. Those of ordinary skill in the art will understand that the concepts of the present invention may be practiced in any suitable environment.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms 'comprises' and / or 'comprising' mean that the stated element, step, operation and / or element does not imply the presence of one or more other elements, steps, operations and / Or additions.

In the present specification, when it is mentioned that a surface (or layer) is on another surface (or layer) or substrate, it may be directly formed on the other surface (or layer) or substrate, or a third surface Or layer) may be interposed.

 Although the terms first, second, third, etc. have been used in various embodiments herein to describe various regions, faces (or layers), etc., it is to be understood that these regions, do. These terms are only used to distinguish certain regions or faces (or layers) from other regions or faces (or layers). Thus, the surface referred to as the first surface in any one embodiment may be referred to as the second surface in other embodiments. Each embodiment described and exemplified herein also includes its complementary embodiment. Like numbers refer to like elements throughout the specification.

The terms used in the embodiments of the present invention may be construed as commonly known to those skilled in the art unless otherwise defined.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The concept of the present invention relates to a photochromic glass whose transmittance is controlled by light. Preferably, the photochromic glass according to the embodiments of the present invention includes a photochromic layer, and the photochromic layer is sandwiched between two layers transmitting light (for example, ultraviolet light and near infrared light) Loses.

1, the photochromic layer of the short wavelength light λ _on irradiated (e.g., ultraviolet rays) increases the absorption of visible light, and the long wavelength light λ _off the transmission when examined (for example, near infrared) And has an increased photochromic property. For example, when the photochromic layer is irradiated with short-wavelength light (? _On ), the absorption of visible light increases. Even when light (? _On ) having a short wavelength irradiated to the photochromic layer is removed, the absorption of visible light is maintained to be increased. When the photochromic layer is irradiated with long-wavelength light (? _Off ), the transmittance of visible light increases. Even when the long-wavelength light (? _Off ) irradiated to the photochromic layer is removed, the transmittance of the visible light is maintained to be increased.

The photochromic layer may include an organic material having photochromic properties. For example, the photochromic layer may comprise at least one of azobenzene, spiro-naphtoxazine, naphtopyran, spiropyran, furylfulgide, stilbene, ), Nitron, fulgide, triarylmethane, or diarylethene. Alternatively, the photochromic layer may be an inorganic oxide. For example, the photochromic layer may be formed of MoO _x , or WO _x .

2 is a cross-sectional view of a photochromic glass according to an embodiment of the present invention.

2, the photochromic glass 10 according to an embodiment of the present invention may include a short wavelength transmitting layer 14, a photochromic layer 12, and a wavelength conversion layer 16. [

The photochromic layer 12 includes the photochromic layer described with reference to FIG. The photochromic layer 12 has a first surface 12a and a second surface 12b which are opposed to each other.

A short wavelength transmitting layer 14 is formed on the first surface 12a of the photochromic layer 12. 3 is a graph showing a change in transmittance according to the wavelength of the short-wavelength transmitting layer 14. Referring to FIG. 3, the short-wavelength transmitting layer 14 may have a high transmittance at a short wavelength. The short-wavelength transmitting layer 14 reflects or absorbs light having a long wavelength, and can have a low transmittance at a long wavelength. For example, the transmittance at a long wavelength of 700 nm or longer may be as low as 50% or less. The short wavelength transmissive layer 14 may be oriented. For example, the transmittance or reflectivity of the short-wavelength transmittance layer 14 may be different depending on the incident direction of light.

The short wavelength transmissive layer 14 may comprise a transparent electrode having a thickness of less than 500 nm. For example, the transparent electrodes are ITO, ZnO: may include B, SnO _2, ZnO, TiO ₂ or _{V 2 O 5: Al, ZnO} : Ga, ZnO. The short-wavelength transmissive layer 14 may be a multi-layered thin film having a thickness of less than 500 nm. The multi-layered photonic thin film may comprise an insulator, or an ultra-thin metal. For example, the insulator may comprise ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ or V ₂ O ₅ . For example, the ultra-thin metal may include Ag, Cu, Al, Au, Pt, Zn, Cr or Mo.

Only the short wavelength light? _{On in the} natural light is irradiated to the photochromic layer 12 because the short-wavelength transmitting layer 14 is disposed on the first surface 12a of the photochromic layer 12. The short wavelength transmitting layer 14 serves as a switch for lowering the visible light transmittance of the photochromic layer 12.

The wavelength conversion layer 16 is formed on the second surface 12b of the photochromic layer 12. 4 is a graph of wavelength conversion characteristics according to the wavelength of the wavelength conversion layer 16. Referring to FIG. 4, the wavelength conversion layer 16 converts light having a short wavelength into light having a long wavelength (? _Off ). The wavelength conversion layer 16 transmits the long wavelength light? _Off and the short wavelength light? _On into long wavelength light.

The wavelength conversion layer 16 may include an organic dye, an inorganic thin film of lanthanide group, TiO _x, or ZnO _x . For example, organic dyes may be selected from the group consisting of metal oxinoid compounds, stilbene compounds, anthracine compounds, oxadiazole metal chelating compounds, polyfluorenes, poly Polyphenylenevinylenes, and mixtures thereof. For example, the lanthanide inorganic thin film may be a compound containing a lanthanide cation and a derivative thereof.

Since the wavelength conversion layer 16 is disposed on the second surface 12b of the photochromic layer 12, only the long wavelength light? _{Off in the} natural light is irradiated to the photochromic layer 12. The wavelength conversion layer 16 serves as a switch for increasing the visible light transmittance of the photochromic layer 12.

5 is a cross-sectional view showing a photochromic glass 20 according to another embodiment of the present invention

Referring to FIG. 5, the photochromic glass 20 according to another embodiment of the present invention may include a short-wavelength transmitting layer 24, a photochromic layer 22, and a long-wavelength transmitting layer 26.

The photochromic layer 22 may be the photochromic layer described with reference to FIG. The photochromic layer 22 has a first surface 22a and a second surface 22b opposite to each other.

A short wavelength transmissive layer 24 is formed on the first surface 22a of the photochromic layer 22. As described with reference to FIG. 3, the short-wavelength transmitting layer 24 can reflect or absorb light of a long wavelength and have low transmittance in a long wavelength. The short wavelength transmissive layer 14 may be oriented. For example, the transmittance or reflectivity of the short-wavelength transmittance layer 14 may be different depending on the incident direction of light.

The short wavelength transmissive layer 24 may comprise a transparent electrode having a thickness of less than 500 nm. For example, ITO, ZnO: may include _{B, SnO 2, ZnO, TiO} 2 or _{V 2 O 5: Al, ZnO} : Ga, ZnO. The short wavelength transmissive layer 24 may be a multilayered thin film of photonic functionality having a thickness of less than 500 nm. The multi-layered photonic thin film may comprise an insulator, or an ultra-thin metal. For example, the insulator may comprise ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ or V ₂ O ₅ . For example, the ultra-thin metal may include Ag, Cu, Al, Au, Pt, Zn, Cr or Mo.

Only the short wavelength light? _{On in the} natural light is irradiated to the photochromic layer 22 because the short wavelength transmitting layer 24 is disposed on the first surface 22a of the photochromic layer 22. The short-wavelength transmitting layer 24 serves as a switch for lowering the visible light transmittance of the photochromic layer 22.

A long wavelength transmissive layer 26 is formed on the second surface 22b of the photochromic layer 20. 6 is a graph showing a change in transmittance with respect to the wavelength of the long wavelength transmissive layer 26. FIG. Referring to FIG. 6, the long wavelength transmitting layer 26 absorbs the short wavelength light? _On . The long wavelength transmissive layer 26 may be oriented. For example, the long-wavelength transmissive layer 26 may have different degrees of transmittance or reflectance depending on the incident direction of light.

The long wavelength transmissive layer 26 may be an inorganic thin film formed to a thickness of 20 to 500 nm. The inorganic thin film may be composed of a light absorbing material having a band gap of 1.5 to 2.5 eV. For example, the light absorbing material may include amorphous silicon, microcrystalline silicon, amorphous silicon-germanium, CIGS, CdTe, GaAs, INP, SiC, SiN and SiO. The long wavelength transmissive layer 26 may further include a dielectric. For example, the dielectric is ITO, ZnO: may include Ga, SnO _2, ZnO, TiO _2, Al ₂ O _3, SiO ₂ or ZrO _2: Al, ZnO.

Due to the disposed on the second surface (22b) of a long wavelength transmitted through layer 26 is a photochromic layer 22, the light (λ _on) of short wavelength is absorbed blocking projection is light (λ _off) of a long wavelength is transmitted through do. Only the light (? _On ) of long wavelength in the natural light is irradiated to the photochromic layer 22. The long wavelength transmissive layer 26 serves as a switch for increasing the visible light transmittance of the photochromic layer 22.

The photochromic layers 12 and 22 according to the embodiments of the present invention can realize various colors depending on the photochromic layer.

The short wavelength transmission layers 14 and 24 according to the embodiments of the present invention can perform the function of low thermal radiation. In other words, the short-wavelength transmitting layers 14 and 24 can improve the heat shielding efficiency by blocking infrared rays.

In embodiments of the present invention, the photochromic glass may be used as sunglass glass. The photochromic glass on the sunglasses may be arranged such that the short wavelength transmission layers 14 and 24 are oriented in the outer direction and the wavelength conversion layer 16 or the long wavelength transmission layer 26 is oriented in the inner direction.

7 is a diagram illustrating the coloring and decoloring principles of the optical switching discoloration sunglasses as embodiments of the present invention. Referring to FIG. 7, when sunlight is irradiated to the sunglass having a high visible light transmittance from the outside, only short-wavelength light (? _Off ) is irradiated to the photochromic layers 12 and 22 by the short-wavelength transmitting layers 14 and 24 . Therefore, the visible light transmittance of the photochromic layers 12 and 22 is lowered, and the sunglasses remain in a colored state. When light is irradiated on the inner surface of the colored sunglasses for the conversion into the discolored state, only the long wavelength light? _On is converted into the photochromic layers 12, 22 by the wavelength conversion layer 16 or the long wavelength transmission layer 26 ). Therefore, the visible light transmittance of the photochromic layers 12 and 22 increases, and the sunglasses return to the high transmittance state.

In the embodiments of the present invention, the photochromic glass can be used as a color change window for a building. The photochromic glass on the window of the building is arranged such that the short wavelength transmission layers 14 and 24 are oriented outdoors and the wavelength conversion layer 16 or long wavelength transmission layer 26 is oriented toward the interior.

8 is a diagram illustrating the coloring and decoloring principles of an optical switching discoloration window for a building as an embodiment of the present invention. Referring to FIG. 8, when sunlight is irradiated from the outside of the optical switching window for buildings, only the light of short wavelength λ _off is irradiated to the photochromic layers 12 and 22 by the short wavelength transmission layers 14 and 24. Therefore, the visible light transmittance of the photochromic layers 12 and 22 is lowered, and the photo-switching discoloration window of the building is shielded by the sunlight outside. When the room light is irradiated on the optical switching window of the building, only the long wavelength light? _On is irradiated onto the photochromic layers 12 and 22 by the wavelength conversion layer 16 or the long wavelength transmission layer 26. Therefore, the visible light transmittance of the photochromic layers 12 and 22 is increased, and the light switching window for buildings returns to the decolored state.

In the embodiments of the present invention, the photochromic glass can be used as an automobile discoloration window. The photochromic glass on the car window is arranged such that the short wavelength transmission layers 14 and 24 are oriented outdoors and the wavelength conversion layer 16 or the long wavelength transmission layer 26 is oriented toward the interior.

9 is a diagram illustrating the coloring and decoloring principles of automotive optical switching discoloration windows as embodiments of the present invention. 9, when sunlight is irradiated from the outside of the automotive optical switching discoloration window, only short-wavelength light (? _Off ) is irradiated to the photochromic layers 12 and 22 by the short-wavelength transmitting layers 14 and 24. Therefore, the visible light transmittance of the photochromic layers 12 and 22 is lowered, and the automobile optical switching discoloration window is shielded from outside sunlight. When the room light is irradiated on the automotive optical switching discoloration window, only the long wavelength light? _On is irradiated to the photochromic layers 12 and 22 by the wavelength conversion layer 16 or the long wavelength transmission layer 26. Therefore, the visible light transmittance of the photochromic layers 12 and 22 increases, and the automotive light switching discoloration window returns to the decolored state.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative and non-restrictive in every respect.

Claims (20)

A photochromic layer having an increase in absorbance of visible light upon irradiation with ultraviolet rays and an increase in transmittance upon irradiation with near infrared rays;
A short-wavelength transmittance layer disposed on the first surface of the photochromic layer and having high transmittance with respect to light having a shorter wavelength than a long wavelength; And
And a wavelength conversion layer disposed on a second surface of the photochromic layer opposite to the first surface and converting light having a short wavelength into a long wavelength. The method according to claim 1,
The photochromic layer may comprise at least one selected from the group consisting of azobenzene, spiro-naphtoxazine, naphtopyran, spiropyran, furylfulgide, stilbene, Photochromic glass comprising nitron, fulgide, triarylmethane, diarylethene, MoO _x , or WO _x . The method according to claim 1,
The transmittance or reflectivity of the short-wavelength transmittance layer is determined by the light incident on the first surface of the short-wavelength transmittance layer and the light incident on the second surface of the short-wavelength transmittance layer opposite to the first surface of the short- Discoloration glass. The method according to claim 1,
Wherein the short wavelength transmissive layer has a thickness of less than 500 nm and comprises a transparent electrode selected from the group consisting of ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ . The method according to claim 1,
Wherein the short wavelength transmitting layer is a multilayered photonic thin film having a thickness of less than 500 nm. 6. The method of claim 5,
Light function of the multi-layer thin film is ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO 2, ZnO, TiO 2 and V ₂ O ₅ photochromic glass comprising selected from the insulator. 6. The method of claim 5,
Wherein the multi-layered photo-functional thin film comprises an ultra-thin metal selected from Ag, Cu, Al, Au, Pt, Zn, Cr and Mo. The method according to claim 1,
Wherein the wavelength conversion layer is an organic dye, a lanthanide inorganic thin film, a photochromic glass containing TiO _x or ZnO _x . A photochromic layer having an increase in absorbance of visible light upon irradiation with ultraviolet rays and an increase in transmittance upon irradiation with near infrared rays;
A short wavelength transmission layer disposed on the first surface of the photochromic layer and having a higher transmittance to light with a shorter wavelength than light having a longer wavelength; And
And a long wavelength transmitting layer disposed on a second surface of the photochromic layer opposite to the first surface and absorbing light of a short wavelength and blocking the long wavelength light. 10. The method of claim 9,
The photochromic layer may comprise at least one selected from the group consisting of azobenzene, spiro-naphtoxazine, naphtopyran, spiropyran, furylfulgide, stilbene, Photochromic glass comprising nitron, fulgide, triarylmethane, diarylethene, MoO _x , or WO _x . 10. The method of claim 9,
The transmittance or reflectivity of the short-wavelength transmittance layer is determined by the light incident on the first surface of the short-wavelength transmittance layer and the light incident on the second surface of the short-wavelength transmittance layer opposite to the first surface of the short- Discoloration glass. 10. The method of claim 9,
Wherein the short wavelength transmissive layer has a thickness of less than 500 nm and comprises a transparent electrode selected from the group consisting of ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO ₂ , ZnO, TiO ₂ and V ₂ O ₅ . 10. The method of claim 9,
Wherein the short wavelength transmitting layer is a multilayered photonic thin film having a thickness of less than 500 nm. 14. The method of claim 13,
Light function thin film is a thin film light function of the multiple layers of the multi-layer is ITO, ZnO: Al, ZnO: Ga, ZnO: B, SnO 2, ZnO, TiO 2 and V ₂ O ₅ photochromic glass comprising selected from the insulator. 14. The method of claim 13,
Wherein the multi-layered photo-functional thin film comprises an ultra-thin metal selected from Ag, Cu, Al, Au, Pt, Zn, Cr and Mo. 10. The method of claim 9,
The transmittance or reflectance of the long wavelength transmissive layer is determined by the light incident on the first surface of the long wavelength transmissive layer and the light incident on the second surface of the long wavelength transmissive layer opposed to the first surface of the long wavelength transmissive layer Photochromic glass containing another. 10. The method of claim 9,
Wherein the long wavelength transmitting layer is an inorganic thin film having a thickness of 20 to 500 nm. 10. The method of claim 9,
Wherein the long wavelength transmissive layer comprises a light absorbing material having a band gap of 1.5 to 2.5 eV. 19. The method of claim 18,
Wherein the light absorbing material comprises amorphous silicon, microcrystalline silicon, amorphous silicon-germanium, CIGS, CdTe, GaAs, INP, SiC, SiN or SiO. 19. The method of claim 18,
Wherein the long wavelength transmissive layer further comprises a dielectric selected from the group consisting of ITO, ZnO: Al, ZnO: Ga, SnO ₂ , ZnO, TiO ₂ , Al ₂ O ₃ , SiO ₂ and ZrO ₂ .

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