Solar spectrum wavelength conversion material and solar cell comprising the same

Abstract

Provided are a solar spectrum wavelength conversion material with improved efficiency and a solar cell comprising the same. According to one embodiment of the present invention, a solar spectrum wavelength conversion material is provided, comprising an aluminum hydroxide precursor anchored with 1-pyrenecarboxylic acid. The solar spectrum wavelength conversion material also comprises an aromatic ring compound or a derivative thereof.

Description

Technical Field

[0001] Embodiments relate to solar spectrum wavelength conversion materials with improved efficiency and solar cells including the same. Background Art

[0002] The most commonly commercialized solar cells are made from a single silicon material and fail to utilize approximately 30% of the light due to a mismatch between the natural solar spectrum and the band gap of the single silicon material. Specifically, the natural solar spectrum has a broad distribution from the ultraviolet to infrared wavelength region (280 to 2500 nm and 0.5 to 4.4 eV), while silicon solar cells are only able to absorb some wavelengths in the ultraviolet and visible wavelength regions.

[0003] Recently, research on utilizing solar spectrum converters has been proposed to address limitations and improve the light conversion efficiency of natural sunlight and silicon solar cells (Chem. Soc. Rev., 2013, 42, 173). That is, a solar spectrum converter is introduced into a silicon solar cell, wherein the solar spectrum converter converts light in the ultraviolet region, where silicon has insufficient solar absorption, or in the infrared region, which has less energy than the silicon band gap, into light in the visible region, which silicon can absorb well.

[0004] According to Wang, Fengyou, et al.'s "Boosting spectral response of multi-crystalline Si solar cells with Mn2+ doped CsPbCl3 quantum dots downconverter," when manganese-doped CsPbCl3 is introduced into multi-crystalline Si solar cells as a downconverter, it can capture more sunlight, resulting in a 6.2% improvement in efficiency based on EQE measurements. This material is a perovskite material and is characterized by its harmfulness to the human body due to the use of lead. It also has the disadvantages of poor UV durability and susceptibility to moisture.

[0005] In Fix, T. et al.'s "Enhancement of silicon solar cells by downshifting with Eu and Tb coordination complexes," CIGS materials using lanthanide elements as dopants were introduced into EVA to increase the efficiency of c-Si cells by 8% (EQE measurement). Although the efficiency of a single cell was increased by 8%, the use of an expensive converter such as CIGS resulted in a drawback that made it difficult to commercialize as a material for c-Si cells. Summary of the Invention

[0006] One aspect of the present invention provides a low-cost aromatic ring-based solar spectrum wavelength conversion material that can improve the photocurrent conversion efficiency of solar cells.

[0007] Another aspect of the present invention provides a solar cell having excellent photocurrent conversion efficiency.

[0008] According to at least one of the embodiments, a solar spectrum wavelength conversion material includes an aluminum hydroxide precursor anchored with 1-pyrenecarboxylic acid.

[0009] In some embodiments, the aluminum hydroxide precursor is any one of the following: aluminum monoacetate, aluminum triacetate, aluminum diacetate, triethylaluminum, trimethylaluminum, aluminum alkoxide, diethylaluminum chloride, aluminum sulfate, aluminum cyanide, aluminum nitrite, aluminum carbonate, aluminum sulfite, aluminum hydroxide, aluminum oxide, aluminum chlorate, aluminum sulfide, aluminum chromate, aluminum chloride, aluminum perchlorate, aluminum nitrate, aluminum permanganate, aluminum bicarbonate, aluminum phosphate, aluminum oxalate, aluminum hydrogen phosphate, aluminum thiosulfate, aluminum chlorite, aluminum hydrogen sulfate, aluminum dichromate, aluminum bromide, aluminum hypochlorite, aluminum chloride hexahydrate, aluminum dihydrogen phosphate, aluminum phosphite, potassium aluminum sulfate dodecahydrate, aluminum bromate, aluminum nitride, or a derivative thereof.

[0010] In some embodiments, the solar spectrum wavelength conversion material includes a structure of Al(OH)3, AlOOH, AlOH, 5Al2O3·2H2O, or Al2O3.

[0011] In some embodiments, the solar spectrum wavelength conversion material further comprises a compound containing one or more selected from the group consisting of: an aromatic ring compound or its derivative, a lanthanide ion (lanthanide-basedions, or lanthanide-based ions or lanthanide ions), and an up-converter material.

[0012] In some embodiments, the aromatic ring compound is any one or more of the following: furan, benzobenzofuran, isobenzobenzofuran, pyrrole, indole, isoindole, thiophene, benzobenzothiophene, benzobenzothiophene, imidazole, benzimidazole, purine, pyrazole, indazole, oxazole, benzoxazolebenzoxazole, oxazoleisoxazole, benzoxazoleisoxazole, thiazole, benzobenzothiazole, benzobenzene, naphthalene, anthracene, pyridine, quinoxaline, acridine, pyrimidine, quinazoline, pyridazine, cinnoline, phthalazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine and derivatives thereof.

[0013] In some embodiments, the solar spectrum wavelength conversion material has a particle size of 0.1 nm to 500 μm.

[0014] In some embodiments, the maximum absorption wavelength of the solar spectrum wavelength conversion material is formed between 300 and 480 nm, and the maximum emission wavelength thereof is formed between 450 and 1200 nm.

[0015] In some embodiments, the solar spectrum wavelength conversion material is in the form of a film having a thickness of 100 μm or less and is dispersed in a light-transmitting resin.

[0016] According to another embodiment, a solar cell is provided on which sunlight is incident and includes a front encapsulation material and a solar spectrum wavelength conversion material according to an embodiment of the present invention at an interface of the solar cell.

[0017] In some embodiments, the solar spectrum wavelength conversion material is coated on the front surface of the solar cell or on the rear surface of the front encapsulation material of the solar cell.

[0018] In some embodiments, the coating is spray coating or screen coating.

[0019] In some embodiments, the encapsulating material is any one of the following: ethylene vinyl acetate (EVA), polyolefin elastomer (POE), cross-linked polyolefin, thermoplastic polyurethane (TPU), polyvinyl butyral (PVB), silicone, silicone / polyurethane hybrid, and ionomer (or ionomer). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. In the drawings:

[0021] Figure 1 shows a photograph showing the luminescence capability of the solar cell prepared by using a UV lamp according to Preparation Example 1;

[0022] Figures 2A to 2E shows a graph showing a change in wavelength shift of a solar cell prepared according to each of Comparative Preparation Examples 1 to 4 and Preparation Example 1;

[0023] Figure 3A and Figure 3B shows an EQE graph of an introduced device of a solar cell according to Example 1, and an enlarged graph showing the efficiency increase on the UV side;

[0024] Figure 3C and 3D shows an EQE graph of an introduced device of a solar cell according to Comparative Example 1, and an enlarged graph showing an increase in efficiency on the UV side;

[0025] Figure 4 A graph showing FTIR analysis of Preparation Example 1 and Comparative Preparation Example 4; and

[0026] Figure 5 A graph showing changes in transmittance according to ultraviolet exposure according to Example 3 and Comparative Example 3 is shown. DETAILED DESCRIPTION

[0027] Hereinafter, the present invention will be described in more detail. However, the present invention will be described in more detail without intending to limit the scope of the present invention.

[0028] According to one embodiment of the present invention, a solar spectrum wavelength conversion material is provided, which includes an aluminum hydroxide precursor anchored with 1-pyrenecarboxylic acid.

[0029] Here, the aluminum hydroxide precursor anchored with 1-pyrenecarboxylic acid is a precursor in which 1-pyrenecarboxylic acid and the aluminum hydroxide precursor are not only physically combined by simple stirring but also anchored by thermal decomposition synthesis. When FTIR analysis is performed, anchoring is defined as achieved if the -OH peak becomes stronger than the C=O peak. The efficiency of the solar cell is significantly higher than when 1-pyrenecarboxylic acid and the aluminum hydroxide precursor are simply mixed.

[0030] Based on the light conversion method, solar spectrum wavelength conversion is mainly divided into down-conversion and up-conversion.

[0031] First, down-conversion is divided into down-shifting of one photon of short wavelength (e.g., ultraviolet light) absorbed with energy higher than the silicon band gap, thereby converting it into one photon of long wavelength region with low energy that silicon can absorb well, and quantum cutting of converting it into two or more photons in low energy region of long wavelength that will be at least twice the absorption wavelength.

[0032] In contrast, a technique called upconversion absorbs two photons in the infrared, which are not absorbed by silicon because the energy is less than its band gap, and converts them into one photon in the high visible region, which is readily absorbed by silicon.

[0033] The present invention relates to a solar spectrum wavelength conversion material having improved efficiency by including low-cost luminescent aluminum hydroxide, and a solar cell including the solar spectrum wavelength conversion material, wherein the material is coated on a solar cell to make a device, or positioned at the interface between the solar cell and a front encapsulation material, and sunlight is incident on the solar cell to cause down-conversion, a non-reflective coating effect and improved durability, thereby improving the photocurrent conversion efficiency due to an increase in short-circuit current.

[0034] In particular, it is preferable to further include an anchoring compound selected from the group consisting of one or more aromatic ring compounds or derivatives thereof, lanthanide ions, and upconverter materials. The upconverter material may be, for example, GaAs or rare earth ions.

[0035] According to one embodiment of the present invention, the aluminum precursor is any one of the following: aluminum monoacetate, aluminum triacetate, aluminum diacetate, triethylaluminum, trimethylaluminum, aluminum alkoxide, diethylaluminum chloride, aluminum sulfate, aluminum cyanide, aluminum nitrite, aluminum carbonate, aluminum sulfite, aluminum hydroxide, aluminum oxide, aluminum chlorate, aluminum sulfide, aluminum chromate, aluminum chloride, aluminum perchlorate, aluminum nitrate, aluminum permanganate, aluminum bicarbonate, aluminum phosphate, aluminum oxalate, aluminum hydrogen phosphate, aluminum thiosulfate, aluminum chlorite, aluminum hydrogen sulfate, aluminum dichromate, aluminum bromide, aluminum hypochlorite, aluminum chloride hexahydrate, aluminum dihydrogen phosphate, aluminum phosphite, potassium aluminum sulfate dodecahydrate, aluminum bromate, aluminum nitride or a derivative thereof.

[0036] The solar spectrum wavelength conversion material may include a structure of Al(OH) 3 , AlOOH, 5Al 2 O 3 · 2H 2 O, Al 2 O 3 , etc., and in the present invention, the above structure is hereinafter referred to as aluminum hydroxide, AlOH or aluminum hydroxide.

[0037] According to one embodiment of the present invention, when appropriately added, aromatic ring compounds and derivatives thereof can be anchored to aluminum hydroxide to change the trap state of aluminum hydroxide, and the position of the light emission wavelength can also be adaptively adjusted.

[0038] Furthermore, when the light absorbed by the aromatic ring compound and its derivatives is at a higher energy than the trapped emission, the energy can be transferred from the aromatic ring compound and its derivatives to the trapped state of the aluminum hydroxide. In this case, the luminescence intensity of the luminescent aluminum hydroxide is amplified by the additional energy transfer. In other words, the aromatic ring compound and its derivatives act as antennas, capturing light in the ultraviolet wavelength region and transferring this light to the aluminum hydroxide.

[0039] Therefore, when 1-pyrenecarboxylic acid is combined and anchored to aluminum hydroxide instead of using aluminum hydroxide alone as a material, an effective increase in UV absorption and stronger visible and near-infrared emission are achieved to induce down-conversion and further improve the photocurrent efficiency. In addition, since the position of the trapped state is lowered, the light emission wavelength shifts to a longer wavelength, so that the Stokes shift (which is the difference between the absorption wavelength and the light emission wavelength) can be increased to reduce the reabsorption of light emitted by the material.

[0040] According to one embodiment of the present invention, as the aromatic cyclic compound, one or more of the following may be selected: an aromatic hydrocarbon, an aromatic heterocyclic compound in which some of the carbon atoms forming the ring are substituted by oxygen, nitrogen or sulfur atoms, or a derivative in which a part of the hydrogen in the aromatic hydrocarbon or aromatic heterocyclic compound molecule is substituted by a functional group.

[0041] According to one embodiment of the present invention, the aromatic ring compound may be selected from one or more of the following: furan, benzobenzofuran, isobenzobenzofuran, pyrrole, indole, isoindole, thiophene, benzobenzothiophene, benzobenzothiophene, imidazole, benzimidazole, purine, pyrazole, indazole, oxazole, benzoxazolebenzoxazole, oxazoleisoxazole, benzoxazoleisoxazole, thiazole, benzobenzothiazole, benzobenzene, naphthalene, anthracene, pyridine, quinoxaline, acridine, pyrimidine, quinazoline, pyridazine, cinnoline, phthalazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine and derivatives thereof.

[0042] Lanthanide ions capable of emitting near-infrared rays can be further added to the material in which 1-pyrenecarboxylic acid is incorporated into the aromatic ring, so that when the material is applied to high-efficiency solar cells with excellent power generation efficiency in the visible and near-infrared wavelength regions, ultraviolet absorption and simultaneous visible and near-infrared emission can achieve a higher photocurrent conversion rate.

[0043] In addition, up-converter materials such as Er3+-doped NaYF4, Tm3+-doped NaYF4 or Ho3+NaYF4 can be added to the material in which 1-pyrenecarboxylic acid is incorporated into the luminescent aluminum hydroxide, so that the solar cell can absorb not only natural sunlight in the high-energy short-wavelength band but also natural sunlight in the low-energy long-wavelength band, thereby further improving the photocurrent efficiency through down-conversion + up-conversion.

[0044] The solar spectrum wavelength conversion material can be prepared by using a hydrothermal method, a sol-gel method, a thermal decomposition synthesis method, etc. In the present invention, the present invention is described in more detail by the thermal decomposition synthesis method, but the scope of the present invention is not limited thereto.

[0045] When synthesizing luminescent aluminum hydroxide by the above-mentioned thermal decomposition synthesis method, a material having a boiling point higher than the thermal decomposition temperature of the aluminum precursor can be used as a solvent. For example, a material having a high boiling point of 200° C. or more, such as hexadecylamine, 1-eicosene, 1-octadecene, docosane, phenyl ether, benzyl ether, octyl ether, oleic acid, oleylamine, and polyisobutylene, is used as a solvent.

[0046] The solvent may act as a solvent, or may function by providing impurities such as carbon, carbonyl groups, oxalate phosphate, and sulfuric acid to control the luminescent properties or further enhance the luminescent performance.

[0047] When 1-pyrenecarboxylic acid is added during the thermal decomposition synthesis step, it can induce absorption of luminescent aluminum hydroxide, increase in light emission, large Stokes shift, etc.

[0048] One or more aluminum precursors and an aromatic ring compound and its derivatives are dispersed in a solvent and reacted at the thermal decomposition temperature of the aluminum precursor. When the reaction is complete, the product is separated and purified to obtain the final luminescent aluminum hydroxide (solar spectrum wavelength conversion material). 1-pyrenecarboxylic acid can be added together with the aluminum precursor at the beginning and then synthesized later, or it can be added separately after the aluminum hydroxide is synthesized and then synthesized to obtain the material.

[0049] Aluminum hydroxide synthesized by thermal decomposition exhibits luminescence properties due to trapped-state emission caused by defects in the metal oxide. When defects exist in the material, trapped-state emission forms a trapped state, which is another energy level between the ground state and the excited state. Electrons transferred from the ground state to the excited state by external energy are stabilized and move to an even lower energy level generated by the defect, emitting light while transferring to the final ground state.

[0050] According to one embodiment of the present invention, the particle size of the solar spectrum wavelength conversion material is preferably 500 μm or less.

[0051] Because the solar spectrum wavelength conversion material is located on the front surface of the solar cell, particles smaller than the wavelength of sunlight incident on the solar cell are advantageous. If the particle size is similar to or larger than the wavelength of sunlight, the incident sunlight may be scattered or reflected, significantly reducing the efficiency of the entire solar cell. Therefore, the particle size of the solar spectrum wavelength conversion material is preferably 0.1 nm to 500 μm, preferably 100 μm or less, and more preferably 10 μm.

[0052] In order to apply solar spectrum wavelength conversion materials to silicon solar cells, they must exhibit both absorption in the ultraviolet wavelength region and light emission in the visible wavelength region. Specifically, it is preferred that the absorption wavelength region be between 300 and 480 nm. Furthermore, it is preferred that the light emission wavelength region be between 450 and 1200 nm.

[0053] According to one embodiment, it is preferred that the encapsulation material into which the solar spectrum wavelength conversion material is introduced is in the form of a film having a thickness of 100 μm or less and is dispersed in a light-transmitting resin.

[0054] In particular, it is preferred that the absorption wavelength region and light emission wavelength region of the solar spectrum wavelength conversion material do not overlap, and materials with a large Stokes shift are advantageous. This is because when the absorption wavelength and light emission wavelength overlap, the reabsorption of light emitted by the material is lost.

[0055] The prepared luminescent aluminum hydroxide can be synthesized to have porosity depending on variables such as precursors, solvents, impurities, thermal decomposition reaction temperature and time, etc. When synthesized to have porosity, the surface area of the prepared luminescent aluminum hydroxide increases, making it possible to improve the durability of the solar module, such as moisture resistance and heat resistance.

[0056] The properties required for solar spectrum wavelength conversion materials, especially for down-conversion materials, include high light emission efficiency, high absorption coefficient, high light safety, ultraviolet absorption, light emission below the wavelength of visible light, and a large Stokes shift (the wavelength difference between the maximum absorption wavelength and the maximum light emission wavelength (Δλ = λ)). 发射 -λ 吸收 ))wait.

[0057] In order to apply down-conversion materials to solar cells, the down-conversion materials should appropriately meet the above-mentioned required properties. Otherwise, the efficiency of the solar cell may be greatly reduced. For example, when a material with low light emission efficiency is introduced into the front surface portion of a solar cell, the material absorbs sunlight but cannot convert the sunlight into visible light, and therefore, may seriously interfere with the sunlight absorption of the solar cell.

[0058] Furthermore, materials with low absorption coefficients, while having high light emission efficiency, have low absorption efficiency and are therefore unlikely to exhibit a down-conversion effect. In the case of materials that absorb in the visible light wavelength region, which is lower than the ultraviolet wavelength region, additional down-conversion effects are unlikely to be expected, as commercially available silicon solar cells already have a high photocurrent conversion efficiency of 90% in the visible light wavelength range. Furthermore, materials with a small Stokes shift are unlikely to exhibit an effective down-conversion effect due to the large overlap between the absorption wavelength and the light emission wavelength, resulting in potential losses due to reabsorption of the emitted light.

[0059] At the same time, when quantum cutting is induced, short-wavelength photons that cannot be absorbed by the solar cell are emitted as two or more long-wavelength photons with high conversion efficiency of the solar cell, so that the efficiency of the solar cell can be greatly improved.

[0060] Hereinafter, in order to demonstrate that the solar spectrum wavelength conversion material prepared according to the present invention is an excellent solar spectrum wavelength conversion material capable of improving the efficiency of solar cells, the present invention will be described with reference to the accompanying drawings.

[0061] Figures 2A-2E The absorption and light emission spectra of the luminescent aluminum hydroxide complex thus prepared are shown. Figure 2A This is the light emission spectrum of a material synthesized using fluorene-9-carboxylic acid as a dopant instead of 1-pyrenecarboxylic acid in the aluminum hydroxide precursor. Like 1-pyrenecarboxylic acid, this material also possesses a carboxylic acid antenna, but it is a compound synthesized by modifying the coefficients of the aromatic ring. As can be seen, the light emission peak is narrowly defined at 460nm. Figure 2B is the light emission spectrum of a compound in which pyrene is added to aluminum hydroxide, wherein pyrene has four aromatic rings like 1-pyrenecarboxylic acid but is in a form without a carboxylic acid antenna, while exhibiting characteristic peaks of light emission at 400 nm and 470 nm. Figure 2C is the light emission spectrum of aluminum hydroxide (AlOH) alone, and shows characteristic light emission peaks at 390 nm and 450 nm. Figure 2D From the results, it can be seen that when the aromatic ring compound is introduced in the thermal decomposition synthesis step, the absorption in the ultraviolet region is improved and the difference between the maximum absorption wavelength and the light emission wavelength is further increased, so that the loss due to reabsorption can be minimized. Figure 2E is the spectrum of the light emitting material in which 1-pyrenecarboxylic acid is anchored to an aluminum hydroxide precursor as claimed in the present invention.

[0062] Through external quantum yield (EQE) measurement, the changes in the light emission properties of luminescent aluminum hydroxide due to the addition of aromatic ring compounds and their derivatives, as well as the improvement in solar cell efficiency due to the aromatic ring compounds and their derivatives, can be more clearly understood.

[0063] Figure 3A and 3B EQE is the EQE of a compound in which 1-pyrenecarboxylic acid is added to aluminum hydroxide. It can be seen that the efficiency of the cell coated with this material in the ultraviolet wavelength band increases compared to a typical bare cell that is not coated.

[0064] According to one embodiment of the present invention, the type and size of the materials constituting the solar cell are not limited thereto. For example, the present invention can be applied to semiconductor-based solar cells such as organic photovoltaic cells (OPV), copper indium gallium selenide (CIGS), CdTe (cadmium telluride), and perovskite, silicon-based solar cells, and solar cells based on a semiconductor-silicon tandem structure (regardless of their material type), and relates to such solar cells characterized by improving the photocurrent conversion efficiency of the solar cell. However, for the purpose of description, a 6-inch single-crystal silicon solar cell is used.

[0065] According to one embodiment of the present invention, this material is coated on a solar cell to make a device, or the solar spectrum wavelength conversion material according to the present invention can be used in a solar cell where sunlight is incident on the solar spectrum wavelength conversion material at the interface between the solar cell and the front encapsulation material.

[0066] Depending on the location of introduction of the converter, the method for introducing the above-mentioned synthetic solar spectrum wavelength conversion material into a solar cell can be a method of manufacturing a sheet material by dispersing the material in a packaging material used to protect the solar cell, a method for applying the material directly on the front surface of a silicon solar cell, or a method for applying the material on the surface of a packaging material bonded to the front surface of the solar cell.

[0067] First, as an encapsulation material for solar cells, materials such as ethylene vinyl acetate (EVA), polyolefin elastomer (POE), cross-linked polyolefin, thermoplastic polyurethane (TPU), polyvinyl butyral (PVB), silicone (also called polysiloxane), silicone / polyurethane hybrids, and ionomers are used, and EVA or POE is most commonly used.

[0068] Generally, a method in which a solar spectrum wavelength conversion material is introduced into an interior of an encapsulation material and positioned on a front surface of a solar cell and then a solar cell module is manufactured by thermal lamination has been widely reported, and there are cases in which this method is applied to commercial production.

[0069] However, in this case, since the refractive index (n to 1.4) of the polymer constituting the encapsulation material, such as EVA or POE, is different from that of the SiN on the surface of the silicon solar cell surface, the x Due to the large difference in refractive index (n to 2.5) between the packaging materials, the light emitted from the light conversion material inside the packaging material cannot travel to the solar cell, and the light waveguiding phenomenon caused by the internal total reflection inside the packaging material becomes dominant, causing the light to travel to the side of the packaging material sheet.

[0070] In contrast, when a solar spectrum wavelength conversion material is applied to the surface of a solar cell or the surface of an encapsulation material, the material becomes located at the interface between the encapsulation material and the solar cell, so that due to the silicon texture structure of several μm or tens of μm, light does not travel to the side of the solar cell, but instead travels to the interior of the solar cell. In addition, if the solar spectrum wavelength conversion material can be adjusted to have a value between the refractive index of the encapsulation material (n to 1.4) and the surface refractive index of the solar cell surface (n to 2.5), then according to Snell's law, it becomes very favorable for light to enter in the direction of the encapsulation material, the light conversion material, and the solar cell, making it possible to further use the light on the side of the solar cell, so that the photocurrent conversion efficiency can be improved. That is, both the down-conversion effect of the solar spectrum wavelength conversion material and the non-reflective coating effect can be expected.

[0071] The solar spectrum wavelength conversion material can be dispersed in a solvent to be applied to the surface of the solar cell, and the method for applying it to the surface of the solar cell can be spin coating, bar coating, spray coating, dip coating, screen printing, etc. In addition, even when applied to the packaging material, all of the above methods can be applied except the spin coating method.

[0072] In the present invention, a spray coating method capable of rapid and uniform coating is used in consideration of commercial production applications of solar spectrum wavelength conversion materials, but the present invention is not limited thereto.

[0073] Hereinafter, preferred embodiments of the present invention will be described in detail, but the following embodiments are provided only to facilitate understanding of the present invention, and the scope of the present invention is not limited to the following embodiments.

[0074] Preparation Example 1: Preparation of luminescent aluminum hydroxide and solar spectrum wavelength conversion material

[0075] In a 3-neck glass bottle, 1.0 to 3.0 g of aluminum acetate (aluminum precursor), 0.01 to 0.1 g of 1-pyrenecarboxylic acid and 50 to 300 mL of 1-octadecene are added, stirred under vacuum, and heated to 100 ° C for pretreatment. After the above state is maintained for about 1 hour, air and moisture are removed under vacuum, and purged with nitrogen or argon. Afterwards, heat is applied to the reactants to about 270 to 320 ° C and kept for 2 to 4 hours for thermal decomposition. Afterwards, cooling is carried out at room temperature, and then post-processing is carried out to prepare a solar spectrum wavelength conversion material.

[0076] [Post-processing]

[0077] The solar spectrum wavelength conversion material was washed using acetone and toluene and then stored.

[0078] ※Information about the raw materials used: aluminum acetate (MW: 162.08 g / mol); Sigma-Aldrich-1-pyrenecarboxylic acid (MW: 246.26 g / mol); Sigma-Aldrich-1-octadecene (MW: 252.48 g / mol); Sigma-Aldrich-acetone (MW: 58.08 g / mol); Daejung-toluene (MW: 92.14 g / mol); JTBaker

[0079] Comparative Preparation Example 1:

[0080] A solar spectrum wavelength conversion material was prepared in the same manner as in Preparation Example 1, except that a dopant having carboxylic acid but not having four aromatic rings (fluorene-9-carboxylic acid) was used instead of 1-pyrenecarboxylic acid as the dopant.

[0081] Comparative Preparation Example 2:

[0082] A solar spectrum wavelength conversion material was prepared in the same manner as in Preparation Example 1, except that a dopant (pyrene) having 964 aromatic rings but not having an antenna that is a carboxylic acid group was used.

[0083] Comparative Preparation Example 3:

[0084] A solar spectrum wavelength conversion material was prepared in the same manner as in Preparation Example 1, except that no dopant was used.

[0085] Comparative Preparation Example 4:

[0086] 1-pyrenecarboxylic acid was added to the prepared Comparative Preparation Example 3, and then stirred for 5 minutes, and then centrifuged using acetone and toluene to prepare a solar spectrum wavelength conversion material.

[0087] Example 1: Fabrication of a Solar Cell Coated with a Solar Spectrum Wavelength Conversion Material

[0088] Uses 6-inch monocrystalline silicon solar cells.

[0089] A solution of the solar spectrum wavelength conversion material prepared according to Preparation Example 1 was applied to the surface of a 6-inch single-crystal silicon cell using a spray coating method. When manufactured in this manner, the solar spectrum wavelength conversion material is located on the surface of the solar cell, and when the EQE (external quantum efficiency) is measured, it can be seen how the efficiency of the solar cell is changed by the applied solar spectrum wavelength conversion material.

[0090] Comparative Example 1

[0091] A solar cell was manufactured in the same manner as in Example 1, except that the type of Preparation Example 1 was changed to the type of Comparative Preparation Example 3.

[0092] Example 2: Fabrication of a solar cell comprising a solar spectrum wavelength conversion material

[0093] The four solar cells coated with the solar spectrum wavelength conversion material prepared in Example 1 were welded into a 2×2 pattern to manufacture a solar cell module.

[0094] Silicon solar cell modules are manufactured by laminating the layers in the order of glass / encapsulant / solar cell conversion material / solar cell / encapsulant / backsheet, starting from the front surface where light is incident. In this manufactured solar cell module, luminescent aluminum hydroxide is located between the encapsulant and solar cell interfaces. Luminescent aluminum hydroxide prepared by the above method is used as the solar spectrum wavelength conversion material constituting the solar cell.

[0095] Comparative Example 2

[0096] A solar cell was manufactured in the same manner as in Example 2, except that a bare cell was used without applying a light conversion material to the solar cell.

[0097] Example 3: Preparation of a solar cell encapsulation material for durability evaluation

[0098] A mixture was prepared by mixing 0.2 parts by weight of aluminum hydroxide anchored with 1-pyrenecarboxylic acid from Preparation Example 1 with 100 parts by weight of ethylene-vinyl acetate copolymer. A crosslinking agent and a crosslinking aid were then blended to prepare an encapsulating material composition. This encapsulating material composition was extruded through a T-die at 100°C to produce an encapsulating material with a thickness of 300 microns.

[0099] Comparative Example 3

[0100] A packaging material was prepared in the same manner as in Example 1, except that the type of Preparation Example 1 was changed to the type of Comparative Preparation Example 4.

[0101] Experimental Example 1: Identification of Luminescence Ability

[0102] The solar cell manufactured according to Example 1 was irradiated with UV light to determine its luminescence ability. When irradiated with UV light, the compound that appears yellow under natural light emits blue. Figure 1 Shown in.

[0103] like Figure 1 As shown, the solar cell of Example 1 manufactured according to the present invention absorbs the UV side and thus has excellent light emitting capability.

[0104] Experimental Example 2: Performance Evaluation of a Solar Cell Including a Photoconversion Device

[0105] In order to compare the performance of the solar cell according to each of Example 1 and Comparative Examples 1 to 4, a photoluminescence (PL) spectrometer was used to measure their respective light emission wavelength bands, and the shift change according to each light emission wavelength band was identified. Figures 2A to 2E The displacement changes are shown in each of the .

[0106] Figure 2A This is the light emission spectrum of a material synthesized using fluorene-9-carboxylic acid as a dopant instead of 1-pyrenecarboxylic acid in an aluminum hydroxide precursor. Like 1-pyrenecarboxylic acid, fluorene-9-carboxylic acid has a carboxylic acid antenna, but it is a compound synthesized by varying the number of aromatic rings. It emits light in a wavelength band earlier than 1-pyrenecarboxylic acid, increasing absorption and the overlap area. Consequently, it is expected that efficiency will decrease. Figure 2B This is the light emission spectrum of a compound in which pyrene, which has four aromatic rings like 1-pyrenecarboxylic acid but lacks a carboxylic acid antenna, is added to aluminum hydroxide. Referring to the light emission spectrum of this type of compound, it emits light in a wavelength band earlier than that of fluorene-9-carboxylic acid. Therefore, the light emission spectrum significantly overlaps with the absorption spectrum, increasing the reabsorption rate and, as a result, reducing the efficiency of the solar cell. Figure 2C It is the light emission spectrum of aluminum hydroxide (AlOH) alone, and shows characteristic peaks of light emission at 390 nm and 450 nm. It is also expected that this spectrum has a lot of overlap with the absorption spectrum. Figure 2D This is the light emission spectrum of a compound in which 1-pyrenecarboxylic acid is not anchored to aluminum hydroxide but stirred together by performing simple physical synthesis. Referring to the light emission spectrum of this type of compound, a peak is observed at 480 nm (which is on the red wavelength band side) due to the influence of 1-pyrenecarboxylic acid, and a peak is also formed at 400 nm, as shown in FIG. Figure 2C As shown, the Figure 2C This is a typical light emission spectrum of aluminum hydroxide. This spectrum appears because 1-pyrenecarboxylic acid is not explicitly anchored to aluminum hydroxide, but rather both are present in the compound. Furthermore, the light emission wavelength is not red-shifted compared to the anchored compound. Figure 2E is the light emission wavelength band of aluminum hydroxide and 1-pyrenecarboxylic acid (which is the compound claimed in this patent). Figures 2A to 2D In comparison, the light emission wavelength band is shifted to 500 nm, which is a long wavelength band, and therefore, the degree of overlap is small, and when applied to a solar cell, the efficiency is improved.

[0107] Experimental Example 3: Confirmation of efficiency increase on the UV side by EQE measurement

[0108] In order to verify the efficiency of introducing the solar spectrum wavelength conversion material, the external quantum efficiency (EQE) of each of the solar cells of Example 1 and Comparative Example 1 was measured and evaluated.

[0109] Figure 3A and 3B is the EQE after spraying a compound in which 1-pyrenecarboxylic acid is introduced into aluminum hydroxide on a 6-inch c-Si cell. Figure 3A , the external quantum efficiency increases compared to the bare cell in the same figure. Figure 3B As shown in , a portion is magnified to observe the effect of improving the quantum efficiency by receiving the solar radiation spectrum from the ultraviolet part. Figure 3B , compared with the bare cell, the sprayed solar cell part is increased, from which it can be seen that there is a down-conversion effect due to the introduction of aluminum hydroxide and 1-pyrenecarboxylic acid.

[0110] In order to identify the difference in EQE efficiency increase between when 1-pyrenecarboxylic acid was synthesized with and without aluminum hydroxide, aluminum hydroxide into which 1-pyrenecarboxylic acid was not introduced (Comparative Preparation Example 3) was sprayed onto a solar cell to measure EQE (Comparative Example 1). The results are shown in FIG. Figure 3C and 3D middle.

[0111] refer to Figure 3C , it can be seen that the efficiency of the solar cell sprayed with aluminum hydroxide increases compared to the bare cell. However, Ref. Figure 3D The enlarged spectrum of the ultraviolet part is shown in FIG. , where the efficiency increase is significantly less than Figure 3B This indicates that the down-conversion efficiency is not significantly increased when 1-pyrenecarboxylic acid is synthesized in the absence of aluminum hydroxide.

[0112] The present invention provides a technology in which the long-term durability of solar cells and solar modules is increased and output degradation over time is minimized to ensure power generation by improving the durability of the packaging material, thereby maintaining the permeability of the packaging material layer when the solar cell and solar module are constructed by dispersing luminescent aluminum hydroxide in the packaging material for sunlight.

[0113] Experimental Example 4: Identification of the difference between anchored and non-anchored materials by FTIR analysis

[0114] FTIR analysis was performed to confirm anchoring of the photoconversion material. Preparation Example 1 and Comparative Preparation Example 4 were prepared by introducing the same materials but using different synthesis methods. In Preparation Example 1, anchoring was achieved through thermal decomposition synthesis, while in Comparative Preparation Example 4, simple stirring was used to physically combine the two materials.

[0115] Figure 4 The CO bond peaks of these peaks in the curve can be regarded as evidence of the presence of acetate. Generally, it is known that at about 1700 cm -1 There will be a C=O bond at 1415 cm-1, but the C-O bond generated in the acetate group is at 1415 cm-1. -1 and ~1570 cm -1 Among these, the monodentate acetate group bound to a single metal forms a C=O bond and has a symmetric stretching mode at 1590 to 1650 cm -1 An asymmetrical bend is formed in the rear side of the Figure 4 As shown in the results shown in FIG, Preparation Example 1 synthesized by applying heat and Comparative Preparation Example 4 in which two materials were introduced without applying heat both showed a peak at 1590 cm -1 In addition, both materials show C=O at 3400 cm -1 The broad -OH peak at is a peak represented by the acid of 1-pyrenecarboxylic acid (Py), and it can be said that both materials contain 1-pyrenecarboxylic acid. In FIG4 , the intensity difference between the two peaks (C═O peak and -OH peak) is important.

[0116] In the graph of Preparation Example 1 (blue solid line), the intensity of the -OH peak is stronger than that of the C=O peak, while in the graph of Comparative Preparation Example 4 (red solid line), their respective intensities are opposite to those in Preparation Example 1. This is likely due to the ratio of -OH to C=O in the sample. When heat is applied, acetate is released from the acetate groups in aluminum acetate, and the anchored 1-pyrenecarboxylic acid is located there. On the other hand, when the two materials are added and simply stirred without applying heat, 1-pyrenecarboxylic acid is not anchored to the aluminum acetate, resulting in a large amount of residual acetate in the aluminum, making the C=O peak of the acetate group clearly visible in the FTIR graph. Therefore, the C=O peak of Preparation Example 1, which was synthesized by applying heat, appears weaker than the -OH peak, indicating a decrease in the ratio of -OH to C=O. In Comparative Preparation Example 4, which was physically mixed, many C=O bonds remain within the material, making the C=O peak appear relatively stronger than the -OH peak. These results indicate that 1-pyrenecarboxylic acid is anchored to aluminum when the synthesis method of this patent is carried out.

[0117] Experimental Example 5: Performance evaluation of solar cells coated with solar spectrum wavelength conversion materials through outdoor evaluation

[0118] An outdoor evaluation device was used to analyze changes in solar cell efficiency based on the introduction of aluminum hydroxide anchored with 1-pyrenecarboxylic acid, and the efficiency changes before and after the aluminum hydroxide coating were specified. Table 1 shows the results of outdoor efficiency measurements of solar cells in which 6-inch single-crystalline silicon solar cells coated with Preparation Example 1 were assembled into a 4-cell micromodule (Example 2) and in which 6-inch single-crystalline silicon solar cells not coated with a light conversion material were assembled into a 4-cell micromodule (Comparative Example 2).

[0119] [Table 1]

[0120]

[0121] As shown in Table 1, when luminescent aluminum hydroxide anchored with 1-pyrenecarboxylic acid was coated, both the short-circuit current and the output increased compared to the uncoated bare cell. This indicates that the increase in the short-circuit current density of the silicon solar cell, which is due to the down-conversion effect caused by the ultraviolet absorption and visible light emission of the photoconversion material, leads to an increase in solar cell efficiency.

[0122] Experimental Example 6: Transmittance Evaluation Based on UV Exposure with or without Anchored Solar Spectrum Wavelength Conversion Material

[0123] A material in which aluminum hydroxide and 1-pyrenecarboxylic acid were anchored by applying heat (Preparation Example 1) and a material obtained by simply adding aluminum hydroxide and 1-pyrenecarboxylic acid together and then centrifuging (Comparative Preparation Example 4) were evaluated for durability. Durability evaluation was performed by transmittance analysis because transmittance analysis can tell how much light a material can receive in a specific wavelength band. Since the light conversion material of the present invention converts light in the ultraviolet wavelength band and increases light conversion efficiency, it is important to have good transmittance in the ultraviolet wavelength band. However, when the solar cell receives ultraviolet light, haze is generated, thereby causing a phenomenon in which light is blocked. When light blocking occurs, it is difficult to pass a large amount of light, so that the efficiency of the solar cell is relatively reduced. Therefore, the durability evaluation of the solar cell is an important factor in the evaluation of the solar cell, and it was investigated which solar spectrum wavelength conversion material synthesized in which way among these materials shows light conversion efficiency when introduced into the solar cell and has a smaller effect on durability.

[0124] Durability evaluation by UV exposure was analyzed using ATLAS's UV-con equipment, and press plates were manufactured using Preparation Example 1 and Comparative Preparation Example 4 as Example 3 and Comparative Example 3, respectively, and these press plates were placed in glass / glass for measurement using UV exposure specifications of 0.5 W, 40° C., and 15 hours.

[0125] Figure 5 3 is a graph comparing the transmittance of Example 3 and Comparative Example 3. The blue solid line and the purple solid line represent the transmittance before and after the UV durability evaluation of Example 3, and the red and green solid lines represent the transmittance before and after the UV durability evaluation of Comparative Example 3. In general, it can be seen that when a material receives a large amount of ultraviolet rays, the transmittance decreases. However, compared with Comparative Example 3 prepared by simple synthesis, Example 3 synthesized by the thermal decomposition method was determined to have excellent durability before and after, and Example 3 after the durability evaluation showed better transmittance than Comparative Example 3 before the durability evaluation. That is, when 1-pyrenecarboxylic acid is anchored to aluminum hydroxide, a new compound is formed that acts advantageously in terms of durability, which results in a slow decrease in light conversion efficiency even after strong UV exposure.

[0126] As described above, when the solar spectrum wavelength conversion material according to the present invention is applied to solar cells, the output can be increased due to the down-conversion effect, and the durability of the solar cell can be improved due to ultraviolet blocking, so that the power generation cost of the solar cell can be reduced and long-term output can be guaranteed.

[0127] When the material is located at the interface of a solar cell in the form of a coating device or encapsulation material into which the material is introduced, an increase in photogenerated current due to the non-reflective coating effect, an anti-potential induced degradation (PID) effect of the module due to the collection of Na+ ions generated in the tempered glass of the solar module, and an anti-light and high temperature induced degradation (LeTID) effect due to the ultraviolet blocking and heat dissipation properties can be expected.

[0128] In addition, unlike related technologies, the one-pot synthesis method can be used to facilitate synthesis and produce low-cost light-harvesting materials. In addition, it also exhibits high efficiency even in single-crystal Si cells with high solar spectrum wavelength conversion efficiency.

[0129] The above embodiment is merely one embodiment for realizing a battery module, and the present disclosure is not limited to this embodiment, and the technical spirit of the present disclosure includes all technical scopes that can be modified in various ways by ordinary technicians in the field to which the present disclosure belongs without departing from the essence of the present disclosure as required by the attached claims.

Claims

1. A solar spectrum wavelength conversion material comprising aluminum hydroxide anchored with 1-pyrenecarboxylic acid, the solar spectrum wavelength conversion material being obtained by the following method, the method comprising combining an aluminum hydroxide precursor and the 1-pyrenecarboxylic acid in a solvent having a boiling point of at least 200° C. and heating the mixture, followed by removing air and moisture and purging with an inert gas, and then heating the resulting mixture at a temperature and for a time sufficient to cause thermal decomposition.

2. The solar spectrum wavelength conversion material according to claim 1, wherein the aluminum hydroxide precursor is any one of the following: aluminum monoacetate, aluminum triacetate, aluminum diacetate, triethylaluminum, trimethylaluminum, aluminum alkoxide, diethylaluminum chloride, aluminum sulfate, aluminum cyanide, aluminum nitrite, aluminum carbonate, aluminum sulfite, aluminum oxide, aluminum chlorate, aluminum sulfide, aluminum chromate, aluminum trichloride, aluminum perchlorate, aluminum nitrate, aluminum permanganate, aluminum bicarbonate, aluminum phosphate, aluminum oxalate, aluminum hydrogen phosphate, aluminum thiosulfate, aluminum chlorite, aluminum hydrogen sulfate, aluminum dichromate, aluminum bromide, aluminum hypochlorite, aluminum chloride hexahydrate, aluminum dihydrogen phosphate, aluminum phosphite, potassium aluminum sulfate dodecahydrate, aluminum bromate, aluminum nitride or its derivatives. 3 . The solar spectrum wavelength conversion material according to claim 1 , wherein the solar spectrum wavelength conversion material comprises a structure of Al(OH) 3 , AlOOH, AlOH, or 5Al 2 O 3 · 2H 2 O. 4 . The solar spectrum wavelength conversion material according to claim 1 , further comprising one or more selected from the group consisting of: an aromatic ring compound or a derivative thereof, a lanthanide ion, and an upconverter material.

5. The solar spectrum wavelength conversion material according to claim 4, wherein the aromatic ring compound is any one or more of the following: furan, benzobenzofuran, isobenzobenzofuran, pyrrole, indole, isoindole, thiophene, benzobenzothiophene, imidazole, benzimidazole, purine, pyrazole, indazole, oxazole, benzoxazolebenzoxazole, oxazoleisoxazole, benzoxazoleisoxazole, thiazole, benzobenzothiazole, benzobenzene, naphthalene, anthracene, pyridine, quinoxaline, acridine, pyrimidine, quinazoline, pyridazine, cinnoline, phthalazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine and derivatives thereof.

6. The solar spectrum wavelength conversion material according to claim 1, wherein the particle size of the solar spectrum wavelength conversion material is 0.1 nm to 500 μm.

7. The solar spectrum wavelength conversion material according to claim 1, wherein the maximum absorption wavelength of the solar spectrum wavelength conversion material is formed between 300 and 480 nm, and the maximum emission wavelength thereof is formed between 450 and 1200 nm. 8 . The solar spectrum wavelength conversion material according to claim 1 , wherein the solar spectrum wavelength conversion material is in the form of a film having a thickness of 100 μm or less and is dispersed in a light-transmitting resin.

9. A solar cell on which sunlight is incident and which comprises a front encapsulation material and a solar spectrum wavelength conversion material located at an interface between the solar cell and the front encapsulation material, wherein the solar spectrum wavelength conversion material is the solar spectrum wavelength conversion material according to any one of claims 1 to 8. 10 . The solar cell according to claim 9 , wherein the solar spectrum wavelength conversion material is coated on the front surface of the solar cell or on the rear surface of the front encapsulation material of the solar cell. The solar cell according to claim 10 , wherein the coating is spray coating or screen coating.

12. The solar cell according to claim 9, wherein the front encapsulation material is any one of the following: ethylene vinyl acetate (EVA), polyolefin elastomer (POE), cross-linked polyolefin, thermoplastic polyurethane (TPU), polyvinyl butyral (PVB), silicone, silicone / polyurethane hybrid, and ionomer.

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