RU2524234C2 - Luminescent coating for improving efficiency of converting energy of incident light and method of producing said coating - Google Patents

Abstract

FIELD: physics, optics.

SUBSTANCE: invention can be used in making solar cells and light-emitting diodes. The luminescent coating is formed from a liquid polymer composition containing, wt %: polyvinyl butyral, having 15-22 wt % hydroxyl groups, 9.0-16.0; cross-linking agent 0.01-8.0; adhesive 0.0-8.0; luminophore or mixture of luminophores, with secondary emission in the spectral range of 400-900 nm, 0.05-3.0 wt %; and a nonpolar aprotic solvent - the balance. Components of said polymer composition are mixed under normal conditions until a homogeneous mass is formed and are deposited in a layer with thickness of 10-200 mcm on a flat, convex, concave surface made of glass, semiconductor material, transparent oxide electroconductive material by pouring or pressure atomisation. The layer is dried at normal conditions until a thin polymer film forms and then held in a drying chamber for 60-90 minutes at temperature of 60-160°C.

EFFECT: high efficiency of converting energy of incident light.

6 cl, 2 dwg, 6 ex

Description

This invention relates to a method for producing a luminescent coating containing inorganic or organic phosphors (or mixtures thereof) used in the manufacture of structural elements of housings (KEK) of solar cells or electrical light sources (eg, LEDs) in which the radiation from the ultraviolet and visible spectral range selectively absorbed and re-emitted with an excellent wavelength, as a result, the density of the spectrally active light flux entering the active absorption increases The covering layer of the photoelectric transducer (PEC) or emanating from lighting or lighting equipment.

The claimed invention relates to a luminescent coating, which is applied to the front or back surface of the KEK from glass, a semiconductor material or a transparent oxide conductive material. The luminescent coating is formed from a liquid polymer composition (GLC), which is applied to the surface of the CEC by pouring a self-flowing polymer composition or by pneumatic (air) spraying. The liquid polymer composition that implements this method, in a generalized form, consists of a polymer, a crosslinking agent, an adhesive or without it, a phosphor or a mixture of phosphors, second emitting in the spectral range of 400 ÷ 900 nm, and a solvent. Inorganic or organic phosphors (or mixtures thereof), which are part of the luminescent coating, selectively absorb radiation from the ultraviolet and visible regions of the electromagnetic spectrum and re-emit it to the region of maximum spectral sensitivity of the light transducer, thereby increasing the photocurrent density or short circuit current.

From the current level of technology, solutions [1-2] are known in which luminescent coatings are used to increase the efficiency of photomultipliers, which transform the short-wave radiation into the longer-wave region of the electromagnetic spectrum due to the Stokes effect.

Such coatings are a polymer layer containing phosphor molecules that absorb light quanta in the wavelength region where the quantum efficiency of the photoelectric transducer is minimal, and they emit secondary radiation in the longer wavelength part of the spectrum, where the quantum efficiency of the photomultiplier is close to unity. As phosphors, semiconductor colloidal quantum dots (obtained according to the method specified in patent RU 2381304 (C1) / 3 /), organic phosphors, rare earth ions and their complexes can be used. Such coatings may have antireflection properties and low production costs.

In the invention US 2010/0012183 (A1) / 4 /, which describes a method for producing a coating on the surface of thin-film chalcogenide photovoltaic modules, this coating may consist of a matrix based on silica gel, silica, epoxy resin or ethylene vinyl acetate. As a luminescent component, phosphors based on inorganic materials of the guest-host type can be included in the matrix, where “guest” is an activator that replaces some atoms of the “host”, and the “host” is the main substance with a certain crystal lattice. As the "host" can be metal oxides, sulfides, nitrides, oxynitrides, and as a "guest" the following group of elements - cerium (Ce), terbium (Tb), europium (Eu), manganese (Mn), praseodium (Pr) . Of the coating methods, the following methods are used: screen printing, silk-screen printing, rolling, extrusion.

The closest technical solution in relation to the claimed invention is a method for producing a transparent film described in WO 2008/110567 (A1), "Photovoltaic modules with improved quantum efficiency" / 5 /. According to this method, a transparent film is included in the photoelectric module as a structural element and / or protective layer and is designed to convert incident electromagnetic radiation using a luminescent material that absorbs incident light in the spectral range from 300 to 500 nm, preferably at 400 nm, where the photovoltaic module has a low value of the external quantum efficiency, and secondly emits in the spectral range from 400 to 700 nm, where the PEC has a high value of the external quantum efficiency activity.

The luminescent material described above contains at least one of the following substances: an organic luminescent material, preferably rhodamine, coumarin, rubrine, laser dye, AIq ₃ , TPD, Gaq ₂ CI; perylene dye, preferably perylene carbonic acid and its derivatives; carbonic naphthalene or its derivatives; Violantron or its derivatives; inorganic luminescent material, preferably Sm ³⁺ , Cr ³⁺ , ZnSe, Eu ²⁺ , Tb ³⁺ , semiconductor quantum dots, Ag nanoparticles.

For the formation of a layer (film) containing a luminescent material on the surface of the photomultiplier, the method of thermal lamination using various polymeric materials based on polyvinyl acetate, polyacrylate and polyepoxide matrices is used.

Unlike the prototype, the claimed luminescent coating is formed after application of the GPC, which implements this method, and drying. GPC is applied to the surface of the KEK by loading or by pneumatic (air) spraying. After application to the surface, the GPC is dried under normal conditions until a thin polymer film is formed, which is kept in an oven for 60 ÷ 90 min at a temperature of 60 to 160 ° C until a heat-resistant luminescent coating is firmly bonded to the surface of the ECC.

A distinctive feature of the above similar technical solutions is the possibility of applying GIC on any type of surface: flat, convex or concave; as well as the use of a wider range of luminescent substances or mixtures thereof, including colloidal quantum dots, silicon dioxide with an attached phosphor, fluorescein and its derivatives; 1,4-bis (5-phenyl-2-oxazolyl) benzene. Each of the phosphors has a certain value of fluorescence wavelengths, which are not a hallmark of analogues, since, based on fundamental assumptions, it is not related to technology as such.

The aim of the claimed invention was the creation of a luminescent coating, which is a durable composite material that allows the use of radiation outside the spectral sensitivity zone of a thin-film photoelectric converter and increases its efficiency.

An additional technical objective of the claimed invention was to reduce the cost of production of solar cells or an electric light source as a result of reducing the cost of a luminescent coating, as well as the use of a GPC to increase the density of the light flux in the required radiation area coming from lighting or lighting equipment.

Achievable technical result in the claimed invention is a method for producing a luminescent coating to increase the efficiency of energy conversion of incident light with improved performance properties, used primarily in solar energy, lighting, optoelectronics and microelectronics.

A schematic representation of a solar cell, in particular a photovoltaic converter with the proposed luminescent coating, is presented in FIG. 1. A schematic representation of an electric light source, in particular an LED with the proposed luminescent coating, is shown in FIG. 2.

A method of obtaining a luminescent coating to increase the efficiency of converting the energy of incident light on the surface of the KEK consists of the main stages: preparation of the GPC, its application to the surface and two-stage drying.

The liquid polymer composition that implements this method consists of a polymer - from 9.0 to 16.0 wt.%; a crosslinking agent from 0.01 to 8.0 wt.%; adhesive - from 0.0 to 8.0 wt.%; a phosphor or a mixture of phosphors that re-emit in the spectral range of 400 ÷ 900 nm, from 0.05 to 3.0 wt.%; and non-polar aprotic solvent - the rest.

GPC as a polymer contains polyvinyl butyral, which contains from 15 to 22 wt.% Hydroxyl groups, including vinyl-alcohol groups.

GPC as a crosslinking agent contains at least one substance: 1,6-diisocyanatohexane (synonym: hexamethylene diisocyanate), 1-isocyano-4 - [(4-isocyanophenyl) methyl] benzene (synonym: methylene diphenyl diisocyanate, 4,4-methylene bis ( phenylisocyanate)) or 2,4-diisocyano-1-methyl-benzene (synonym: toluene diisocyanate).

GPC as an adhesive contains at least one substance: (3-isocyanatopropyl) trimethoxysilane (synonym: 3- (trimethoxysilyl) propyl isocyanate) or (3-isocyanatopropyl) triethoxysilane (synonym: 3- (triethoxysilyl) propyl isocyanate). The proposed non-adhesive luminescent coating in its composition is applied to the surface of semiconductor materials or transparent oxide conductive materials (for example, indium tin oxide coating - ITO coating), or to the surface of a CEC with a substrate structure, or on a transparent conductive coating of a CEC with a substrate structure.

GPC as a phosphor contains at least one substance or mixture of substances from the following groups: fluorescein or its derivatives; 1,4-bis (5-phenyl-2-oxazolyl) benzene; coumarins; rhodamines; colloidal quantum dots; silicon dioxide-based luminescent nanoparticles with attached fluorescent dyes; inorganic phosphors based on yttrium-aluminum garnet (synonym: YAG), activated by cerium (Ce), terbium (Tb), europium (Eu), neodymium (Nd).

GPC as a non-polar aprotic solvent contains at least one substance: tetrahydrofuran, butyl acetate, or dioxane.

The above GPC components are mixed under normal conditions until a homogeneous mass is formed and applied with a layer of thickness from 10 to 200 μm on a flat, convex, concave surface of the CEC of glass, a semiconductor material, a transparent oxide electrically conductive material by pouring or by pneumatic (air) spraying. After applying the GPC to the surface of the ECEC, the resulting coating is dried under normal conditions until a thin polymer film is formed, which is kept in an oven for 60 ÷ 90 minutes at a temperature of 60 to 160 ° C until a heat-resistant luminescent coating is firmly bonded to the ECC surface.

The proposed luminescent coating has high adhesive properties to a glass surface; resistant to alkalis, acids and moisture; withstands temperatures from -40 ° C to + 160 ° C without changing performance.

Due to the combination of essential features belonging to phosphors, the main technical result is achieved, consisting in the fact that a luminescent coating is obtained with a thickness of 10 to 200 μm, which selectively absorbs radiation from the ultraviolet and visible regions of the electromagnetic spectrum and secondly emits it into the region of maximum spectral sensitivity of the photomultiplier, which, accordingly, leads to an increase in the energy conversion efficiency of the incident light. In particular, if the maximum values of the fluorescence fluorescence wavelengths of phosphors fall in the range from 400 to 900 nm, then the luminescent coating allows to increase the photomultiplier efficiency by 5% from the initial value of the photomultiplier efficiency without coating.

In an advantageous embodiment, when along with photostability it is desirable to obtain a relative fluorescence quantum yield above 80%, it is proposed to use phosphor mixtures that absorb incident short-wave light in the spectral range from 300 to 500 nm and emit secondarily from 400 to 900 nm.

A brief description of the drawings of the claimed invention is presented in Fig.1-2 as an illustration in accordance with the variants of implementation of the claimed invention and does not limit the technical results achieved.

Figure 1 shows a schematic illustration of a solar cell, in particular a photovoltaic converter with the proposed luminescent coating.

Figure 1 introduced the notation:

1 - luminescent coating;

2 - a protective glass coating;

3 - transparent oxide conductive layer;

4 - layer of n-semiconductor (CdS, ZnS and others);

5 - p-semiconductor layer (CdTe, CuInGaSe ₂ and others);

6 - back contact;

7 - a protective glass.

Figure 2 shows a schematic illustration of an electric light source, in particular an LED with the proposed luminescent coating.

Figure 2 introduced the notation:

1 - source of primary radiation (LED);

2 - a protective glass coating;

3 - luminescent coating;

4 - luminous flux emanating from the source of primary radiation;

5 - secondary luminous flux with an excellent wavelength, emanating from lighting or lighting equipment.

The implementation of the invention consists in the fact that in a preferred embodiment, the luminescent coating, which is obtained after removal of the solvent from the GPC, has the following quantitative composition in a generalized form: polymer - 68.2 wt.%, Crosslinking agent - 15.8 wt.%, Adhesive - 15.3 wt.%, Phosphor or a mixture of phosphors - 0.7 wt.% A mixture of phosphors, allowing to cover a wider absorption spectrum, consists of coumarin 6 and 1,4-bis (5-phenyloxazol-2-yl) benzene.

Examples of obtaining the claimed luminescent coating:

Example 1. The composition of the GPC using colloidal quantum dots and a method for producing a luminescent coating KEK, the surface of which is made of semiconductor materials. This luminescent coating increases the color rendering efficiency of an electric light source.

Mix 25 volume parts (parts by volume) of a solution of polyvinyl butyral (PVB) in a non-polar aprotic solvent (HAP) with 20 parts by volume a solution of a phosphor in NAR, which is previously incubated in an ultrasonic bath for 20 minutes, with 1 vol.h. crosslinking agent.

In this example, the concentration of polyvinyl butyral in the GPC should be in the range of 16.00 ± 0.01 wt.%, Crosslinking agent - 8.00 ± 0.01 wt.%, Phosphor - 0.30 ± 0.02 wt.% And NAP - the rest.

As a crosslinking agent, 1,6-diisocyanatohexane is used.

Colloidal quantum dots CdSe (wavelength of maximum fluorescence in the range of 520 ± 15 nm), or CdSe / ZnSe (wavelength of maximum of fluorescence in the range of 520 ± 15 nm), or PbSe (wavelength of maximum fluorescence in the range of 790 ± 15, are used as a phosphor) nm).

As a non-polar aprotic solvent (HAP), tetrahydrofuran is used.

To apply GPC to a semiconductor material, the method of filling a self-flowing polymer (paint) composition is used.

The resulting coating is kept in an oven for 90 minutes at a temperature of 80 ° C until a heat-resistant luminescent coating is formed, strongly bonded to the surface.

Example 2. The composition of the GPC using a mixture of organic phosphors and a method for producing a luminescent coating KEK, the surface of which is made of transparent oxide conductive coatings. This luminescent coating by 5% increases the efficiency of converting the energy of the incident light on the surface of the solar cells into electrical energy.

It is carried out analogously to example 1, but as a phosphor using a mixture of phosphors, consisting of 12.5 vol.h. coumarin 6 solution (wavelength of maximum fluorescence in the range of 520 ± 15 nm) in NAR and 7.5 vol.h. a solution of 1,4-bis (5-phenyloxazol-2-yl) benzene (wavelength of maximum fluorescence in the range of 430 ± 15 nm) in HAP.

Butyl acetate is used as HAP.

The concentration of polyvinyl butyral in the GPC should be in the range of 16.00 ± 0.01 wt.%, A crosslinking agent - 8.00 ± 0.01 wt.%, Phosphors: coumarin 6 - 0.70 ± 0.02 wt.%, 1 , 4-bis (5-phenyloxazol-2-yl) benzene - 0.30 ± 0.02 wt.%) And HAP - the rest.

Example 3. The composition of the GPC using a mixture of organic phosphors and a method for producing a luminescent coating KEK, the surface of which is made of glass.

It is carried out analogously to example 2, but as a cross-linking agent, 1-isociano-4 - [(4-isocyanophenyl) methyl] benzene is used.

An additional 1 vol.h. adhesive, which is (3-isocyanatopropyl) triethoxysilane.

Instead of coumarin 6 (wavelength of maximum fluorescence in the range of 520 ± 15 nm), rhodamine 6G (wavelength of maximum of fluorescence in the range of 550 ± 10 nm) or fluorescein (wavelength of maximum of fluorescence in the range of 510 ± 5 nm) are used.

Dioxane is used as HAP.

In this example, the concentration of polyvinyl butyral in the GPC should be in the range of 16.00 ± 0.01 wt.%, Crosslinking agent - 8.00 ± 0.01 wt.%, Adhesive - 8.00 ± 0.01 wt.%, Phosphor - 0.30 ± 0.02 wt.% And NAR - the rest.

Example 4. The composition of the GPC using an inorganic phosphor and a method for producing a luminescent coating of an optically transparent KEK electric light source, the surface of which is made of glass.

It is carried out analogously to example 1, but 2,4-diisociano-1-methyl-benzene is used as a crosslinking agent.

Additionally enter 1 about.h. an adhesive used as (3-isocyanatopropyl) trimethoxysilane.

As the phosphor, nanoparticles based on yttrium-aluminum garnet activated by cerium (Ce), YAG: Ce (wavelength of maximum fluorescence in the range of 520 ± 15 nm), or yttrium-aluminum garnet activated by terbium (Tb), YAG: Tb ( the wavelength of the maximum fluorescence in the range of 525 ± 35 nm), or yttrium-aluminum garnet activated by europium (Eu), YAG: Eu (the wavelength of the maximum of fluorescence in the range of 620 ± 20 nm), or yttrium-aluminum garnet activated by neodymium (Nd ), YAG: Nd (wavelength of maximum fluorescence in the range of 880 ± 20 nm )

As NAR use tetrahydrofuran.

In this example, the concentration of polyvinyl butyral in the GPC should be in the range of 16.00 ± 0.01 wt.%, Crosslinking agent - 8.00 ± 0.01 wt.%, Adhesive - 8.00 ± 0.01 wt.%, Phosphor - 3.00 ± 0.01 wt.% And NAP - the rest.

The resulting coating is kept in an oven for 60 minutes at a temperature of 150 ° C.

Example 5. The composition of the GPC using luminescent nanoparticles of silicon dioxide with covalently attached phosphor fluorescein SiO ₂ -FITC and a method for producing a luminescent coating KEK, the surface of which is made of glass. This luminescent coating by 5% increases the efficiency of converting the energy of the incident light on the surface of the solar cells into electrical energy.

It is carried out analogously to example 4, but silicon dioxide nanoparticles with covalently luminophore fluorescein SiO ₂ -FITC (wavelength of maximum fluorescence in the region of 510 ± 10 nm) are used as a phosphor.

In this example, the concentration of the components of the GPC should correspond to the data given in example 3.

Example 6. The composition of the GPC for applying to the front or back surface of the KEK solar cells or electrical light sources of glass, a semiconductor material or a transparent oxide conductive material by pneumatic spraying using airbrushing equipment.

The preparation of the GPC is carried out similarly to examples 1-3, followed by dilution of the GIC with a solvent 2 times.

Application is carried out under the following conditions: air pressure - 2 atm, airbrush nozzle size - 0.2 mm.

Subsequent operations after application are carried out in full accordance with examples 1-3.

Information sources:

1.WO2008046147 (A1) G02F 2/02, H01L 21/36, H01L 21/36, H01L 31 / 0264. / Up and down conversion using quantum dot arrays. Priority date 10/17/2007. Patentee: Newsouth innovations PTY Limited.

2. US 2007/295383 (A1) H02N 6/00. Wavelength-converting phosphors for enhancing the efficiency of a photovoltaic device. Priority date 03.30.2007. Patentee: INTEMATIX CORP.

3. RU 2381304 (C1) C30B 7/00, C30B 29/46, C09K 11/02, C09K 11/88, B82B 3/00. The method of synthesis of semiconductor quantum dots. Priority date 08.21.2008. Patent holder: Federal State Unitary Enterprise "Research Institute of Applied Acoustics" (RU).

4. US 2010/0012183 (A1) H01L 31/00, B05D 5/12. Thin film solar cell having photo-luminescent medium coated therein and method for fabricating the same. Priority Date 07.17.2008. Patentee: Chih-Hung Yeh, Miaoli.

5. WO 2008/110567 (A1) H01L 31/055, H01L 31/0216, H01L 31/048. Photovoltaic modules with improved quantum efficiency. Priority date 13.03.2007. Patentee: BASF SE (DE), Bohm Arno, Grimm Axel, Richards Bryce.

Claims (6)

1. Luminescent coating for solar cells or LEDs, characterized in that it is formed from a liquid polymer composition consisting of a polyvinyl butyral polymer having in its composition from 15 to 22 wt.% Hydroxyl groups, from 9.0 to 16.0 wt. %; a crosslinking agent from 0.01 to 8.0 wt.%; adhesive - from 0.0 to 8.0 wt.%; a phosphor or a mixture of phosphors that re-emit in the spectral range of 400 ÷ 900 nm, from 0.05 to 3.0 wt.%; and non-polar aprotic solvent - the rest. 2. The luminescent coating according to claim 1, characterized in that the crosslinking agent contains at least one substance: 4,4-methylene bis (phenylisocyanate), or hexamethylene diisocyanate, or toluene diisocyanate, or mixtures thereof. 3. The luminescent coating according to claim 1, characterized in that the adhesive contains at least one substance: isocyanatopropyltrimethoxysilane or isocyanatopropyltriethoxysilane. 4. The luminescent coating according to claim 1, characterized in that as a phosphor contains at least one substance or mixture of substances from the following groups: fluorescein or its derivatives; 1,4-bis (5-phenyl-2-oxazolyl) benzene; coumarins; rhodamines; colloidal quantum dots; silicon dioxide-based luminescent nanoparticles with attached fluorescent dyes; inorganic phosphors based on yttrium-aluminum garnet containing the following activators: cerium (Ce), terbium (Tb), europium (Eu), neodymium (Nd). 5. The luminescent coating according to claim 1, characterized in that as a non-polar aprotic solvent contains at least one substance: either tetrahydrofuran, or butyl acetate, or dioxane. 6. The method for producing a luminescent coating according to claim 1, characterized in that the components of the liquid polymer composition are mixed under normal conditions until a homogeneous mass is formed and applied with a layer thickness of 10 to 200 microns on a flat, convex, concave surface of glass, a semiconductor material, transparent oxide conductive material by filling or pneumatic spraying, and then dried under normal conditions to form a thin polymer film and kept in an oven for 60 ÷ 90 min at temperature from 60 to 160 ° C.

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