JP2015122470A - Method of manufacturing liquid up-conversion microcapsule, and solar battery module and display device having up-conversion layer using the liquid up-conversion microcapsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which manufacturing costs increase since an end surface for holding an up-conversion film layer between a transparent insulation film and a light reflection layer needs to be sealed when the up-conversion film layer is liquid, and a member and a processes for the sealing are additionally necessary.SOLUTION: Liquid up-conversion microcapsules are formed by employing a process of forming a liquid up-conversion mixture and a stirring process of mixing a liquid up-conversion liquid with a solvent and stirring them. Consequently, a liquid up-conversion mixture can be used at low cost.

Description

  The present invention relates to a method for producing a liquid up-conversion microcapsule, a solar cell module having an up-conversion layer using the liquid up-conversion microcapsule, and a display device.

  While importance is placed on reducing the load on the global environment, great expectations are placed on solar cells that photoelectrically convert solar energy directly into electrical energy. There are various types of solar cells, but at present the mainstream is silicon solar cells.

  Silicon-based solar cells have a limited wavelength range with high spectral sensitivity, and the problem of not being able to fully utilize sunlight has been pointed out. As one means for solving this problem, up-conversion has been studied in which light having a long wavelength is absorbed and light having a shorter wavelength is emitted to convert the wavelength of the light.

  Solid light conversion elements having various types of up-conversion functions have been studied, but at present, sufficient quantum efficiency has not been obtained. Under such circumstances, a liquid light conversion element has been proposed.

  Patent Document 1 uses a light conversion element and a light conversion element obtained by dissolving and / or dispersing an organic photosensitizer molecule and an organic light emitting molecule, which are a combination showing a triplet-triplet annihilation process, in an ionic liquid. A solar cell in which the up-conversion film layer was disposed is disclosed.

WO2012 / 050137A1

  Patent Document 1 discloses, as an example, a solar cell in which an up-conversion film layer using a light conversion element is disposed between a transparent insulating film and a light reflection layer. However, it is not disclosed how to specifically arrange the liquid light conversion element. Further, when the up-conversion film layer is in a liquid state, it is necessary to seal the end face to keep it between the transparent insulating film and the light reflecting layer. When sealing is performed, the number of members and processes increases, which causes a problem that the manufacturing cost increases.

  The method for forming a liquid up-conversion microcapsule according to the present invention includes a step of forming a liquid up-conversion mixture, and a stirring step of mixing and stirring the liquid up-conversion liquid in a solvent. .

  The solar cell module according to the present invention has, from the light receiving surface side, a light receiving surface side protective layer, a solar battery cell, a back surface side sealing layer, and a back surface protective layer in this order, and a liquid is provided on the back surface side of the solar battery cell. It is characterized by having an up-conversion layer using up-conversion microcapsules. The liquid up-conversion microcapsules are formed through a step of forming a liquid up-conversion mixture and a stirring step of mixing and stirring the liquid up-conversion liquid in a solvent.

  A liquid up-conversion mixture is formed using a step of forming a liquid up-conversion mixture and a stirring step of mixing and stirring the solvent and the liquid up-conversion liquid, thereby forming a liquid up-conversion microcapsule. The mixture can be used at low cost.

  Further, by arranging an up-conversion layer using a liquid up-conversion microcapsule on the back surface side of the solar battery cell, it is possible to provide a solar cell module with high efficiency and low manufacturing cost.

1 illustrates Embodiment 1 of the present invention and schematically illustrates a method for producing a liquid up-conversion microcapsule. Embodiment 5 of the present invention, which schematically shows a solar cell module using a liquid up-conversion microcapsule. Embodiment 6 of the present invention, which schematically shows a solar cell module using a liquid up-conversion microcapsule. Embodiment 7 of the present invention, which schematically shows a display device using liquid up-conversion microcapsules. The another example of Embodiment 8 of this invention is shown, Comprising: The display apparatus using a liquid up-conversion microcapsule is shown typically.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
A method for producing a liquid up-conversion microcapsule according to Embodiment 1 will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a method for producing a liquid microcapsule according to this embodiment.

First, in the liquid up-conversion mixture forming step S1 (S is a step), a liquid up-conversion mixture was formed. 1 × 10 ⁻⁵ mol / l of organic sensitizing molecule meso-tetraphenyl-tetrabenzoporphyrin palladium to 1-butyl-2,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide, which is an ionic liquid, organic It was formed by adding 1 × 10 ⁻³ mol / l of perylene as a luminescent molecule and dissolving it. A high quantum efficiency of 10% was achieved.

  The liquid up-conversion mixture formed in this embodiment is obtained by adding an organic sensitizing molecule and an organic light emitting molecule to an ionic liquid serving as a solvent. 1-Butyl-2,3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide is used as the ionic liquid, meso-tetraphenyl-tetrabenzoporphyrin palladium is used as the organic sensitizing molecule, and perylene is used as the organic light emitting molecule. Using. The excitation energy of one photon absorbed by the organic sensitizing molecule is transmitted to the organic light emitting molecule, and the organic light emitting molecule becomes an excited triplet state. The organic light-emitting molecules in the excited triplet state collide with each other and transmit energy by a Dexter mechanism, which is a mechanism in which the excited electron state is transmitted by overlapping wave functions, and generate one photon. The energy of the generated photons is larger than the energy of the incident photons. This is because one generated photon is generated by two excited organic light emitting molecules. Therefore, light having a long wavelength can be absorbed and converted to light having a shorter wavelength.

  The liquid up-conversion mixture needs to be in liquid form because the excited organic light emitting molecules need to collide with each other. The reason why the ionic liquid is used as the solvent is that it has a low vapor pressure and is chemically stable.

  Next, in the stirring step S2, 5 wt% of the liquid up-conversion mixture was added to the PVA solution and stirred. Stirring was performed with a stirrer while applying ultrasonic waves for about 4 hours. The PVA solution is prepared by adding 5 wt% of Bhopal PVA-250C manufactured by Kuraray Co., Ltd. to pure water and dissolving it by heating and stirring. A suitable amount of a cross-linking agent such as Olga-Tix TC-310 manufactured by Matsumoto Fine Chemical Co., Ltd. may be added to the PVA solution. When a cross-linking agent is added, the stability of the PVA solution is improved and the microcapsules are hardly broken.

  Emulsification occurred by stirring, and liquid up-conversion microcapsules were formed. The diameter of the liquid up-conversion microcapsule was about 3 μm to 10 μm. The liquid up-conversion microcapsule in this specification refers to a droplet of the liquid up-conversion mixture.

  Instead of applying ultrasonic waves and stirring, a colloid mill or membrane emulsification may be used. When membrane emulsification is used, liquid up-conversion microcapsules with a more uniform diameter can be formed.

  By applying a PVA solution containing liquid up-conversion microcapsules and drying, an up-conversion layer using the liquid up-conversion microcapsules can be formed. Drying is removing the water | moisture content in PVA liquid. Further, it is desirable to deaerate the atmosphere after drying. This is to prevent deactivation of the excited phosphor by dissolved oxygen.

  In addition, by creating a liquid containing a plurality of different liquid up-conversion microcapsules, it is possible to widen the wavelength region of light for wavelength conversion.

[Embodiment 2]
The method for producing the liquid up-conversion microcapsule according to Embodiment 2 will be described as follows. The difference from Embodiment 1 is the solution used in the stirring step. A description of the same points as those in the first embodiment will be omitted.

  In this embodiment, 50 wt% of the liquid up-conversion mixture was mixed with the acrylic monomer to which the photopolymerization initiator was added and stirred to produce a liquid up-conversion microcapsule.

  Furthermore, after an acrylic polymer containing liquid up-conversion microcapsules was applied to the substrate, an up-conversion layer was formed by irradiating ultraviolet rays. Since it can be cured by ultraviolet irradiation, it can be formed on a substrate having low heat resistance.

[Embodiment 3]
The method for producing the liquid up-conversion microcapsule according to Embodiment 3 will be described as follows. The difference from the first embodiment is the material used in the liquid up-conversion mixture forming step. The description overlapping with the first embodiment will be omitted.

  In the present embodiment, in the liquid up-conversion mixture forming step, an organic sensitizing molecule is added to and dissolved in the organic light-emitting molecular liquid to form a liquid up-conversion mixture. In order to realize high quantum efficiency, it is necessary to be a liquid, but since the organic light emitting molecular liquid is in a liquid state, there is an advantage that a solvent is unnecessary. Specifically, 9,10-diphenylanthracene having a branched alkyl chain was used as the organic light-emitting molecular liquid, and Pt (II) porphyrin having a branched alkyl chain was used as the organic sensitizing molecule. Moreover, 0.01 mol% of organic sensitizing molecules were added to the organic light emitting molecular liquid.

  By using the material described in this embodiment, the alkyl group around the chromophore prevents oxygen from entering, so that there is little deactivation of the exciton (quenching) by oxygen, and the membrane is sealed (passivation). ) Becomes easier.

  Furthermore, in the stirring step, the solvent and the up-conversion liquid were mixed and stirred. A PVA solution was used as a solvent to be a microcapsule. A liquid up-conversion mixture was used as the up-conversion liquid. A liquid up-conversion microcapsule was formed by adding 5 wt% of the liquid up-conversion mixture to the PVA solution and stirring.

[Embodiment 4]
The method for producing the liquid up-conversion microcapsule according to Embodiment 4 will be described as follows. The difference from Embodiment 3 is the organic sensitizing molecule used in the liquid upconversion mixture forming step. The description overlapping with the third embodiment will be omitted.

  The organic increasing molecule uses Pt, which is a heavy atom having a large atomic number as a metal atom, to form a triplet by spin-orbit interaction due to the heavy atom effect. In this embodiment, a material having a long π conjugate length is used as the organic sensitizing molecule. By increasing the π conjugate length, it is possible to perform up-conversion for light having a wavelength in the infrared region. Specifically, tetraanthracenyl porphyrin, a porphyrin having an expanded area, was used as the organic sensitizing molecule. Polyphyrin having a long π-conjugated length that is greater than that of a dimer can also be used. This molecule can also be used as the organic sensitizing molecule of Example 1.

  In the liquid up-conversion mixture forming step, an organic sensitizing molecule was added to and dissolved in the organic light emitting molecular liquid to form a liquid up-conversion mixture. Furthermore, in the stirring step, a liquid up-conversion microcapsule was formed by adding the liquid up-conversion mixture to the PVA solution and stirring.

[Embodiment 5]
A solar cell module having an up-conversion layer using the liquid up-conversion microcapsule according to Embodiment 5 will be described as follows.

  As shown in FIG. 2, the solar cell module 100 of the present embodiment includes a light receiving surface protective layer 11, a light receiving surface side sealing layer 12, a solar battery cell 13, an up-conversion layer 14, a back surface side sealing layer 15, and a back surface. A protective layer 16 is provided. In addition, the light incident side of the solar battery cell was the light receiving surface side, and the opposite side of the light receiving surface was the back surface side.

  Although not shown in FIG. 2, in order to obtain sufficient output power as the solar cell module 100, a plurality of solar cells were electrically connected in series using internal wiring. Furthermore, the solar cell module 100 has two extraction electrodes on the positive electrode side and the negative electrode side, one end of each extraction electrode is electrically connected to the solar cell, and one end on the opposite side of the extraction electrode is Electrically connected to the terminal box.

  A glass substrate having a thickness of about 3 mm was used as the light-receiving surface protective layer 11, and EVA (ethylene-vinyl acetate copolymer) was used as the sealing layer as the light-receiving surface side sealing layer 12. A resin such as an ionomer resin may be used.

  A crystalline silicon solar cell produced using a polycrystalline silicon wafer was used as the solar cell 13. As the solar cell 13, a crystalline silicon solar cell manufactured using a single crystal silicon wafer may be used. Further, a thin film silicon solar battery cell using amorphous or microcrystalline silicon may be used. In this case, the light receiving surface side sealing layer 22 is not necessary.

  The up-conversion layer 14 was formed by applying a film containing the liquid up-conversion microcapsule described in Embodiment 1 onto the solar battery cell 13 and drying it. The thickness was about 4 mm. EVA having a thickness of about 0.6 mm was used as the back side sealing layer 15, and white PET was used as the back side protective layer 16.

  By arranging the up-conversion layer on the back surface side of the solar battery cell, the light transmitted through the solar battery cell can be converted into light having a shorter wavelength and returned to the solar battery cell. Therefore, the amount of light in the wavelength region with high spectral sensitivity incident on the solar battery cell 13 is increased, the short-circuit current value of the solar battery cell is increased, and the conversion efficiency can be improved. As a result, a solar cell module with high conversion efficiency could be obtained.

  It is more desirable to arrange only on the back surface side of the solar battery cell and not to place an up-conversion layer between adjacent solar battery cells. The up-conversion layer 14 may also absorb light having a wavelength that can be absorbed by the solar battery cell. Therefore, returning the light to the light receiving surface side of the solar cell 13 by reflection of the back surface protective layer 16 without arranging an up-conversion layer between the solar cells leads to an increase in the short-circuit current value of the solar cell. It is.

  In addition, it is not necessary to put a liquid up-conversion mixture between glass substrates and dispose it on the back side of the solar cell, and it is not necessary to seal the end surface, thus forming a low-cost solar cell module. Became possible.

  Furthermore, the up-conversion layer can be protected by covering the up-conversion layer with the back surface side sealing layer.

  In the present embodiment, when forming the up-conversion layer, a method of applying a liquid containing liquid up-conversion microcapsules on the solar cell and drying it was used. You may use the method of apply | coating and drying the liquid containing a conversion microcapsule.

[Embodiment 6]
A solar cell module having an up-conversion layer using the liquid up-conversion microcapsule according to Embodiment 6 will be described as follows. The difference between the third embodiment and the second embodiment is that the up-conversion layer is sandwiched between the sealing layers. The description overlapping with the fifth embodiment is omitted.

  As shown in FIG. 3, the solar cell module 200 of the present embodiment includes a light receiving surface side protective layer 21, a light receiving surface side sealing layer 22, solar cells 23, a back surface side sealing layer 25, an up-conversion film 24, An up-conversion film sealing layer 27 and a back surface protective layer 26 are provided. By sandwiching the up-conversion layer 24 with the sealing layer, it is possible to suppress the occurrence of cracks in the up-conversion layer. Rather than sandwiching between solar cell and backside sealing layer with different stress coefficients, sandwiching between backside sealing layer and up-conversion film sealing layer using EVA which is the same material However, the stress applied to the up-conversion layer is small.

  In this embodiment, although the case where EVA was used as a light-receiving surface side sealing layer, a back surface side sealing layer, and an up-conversion film sealing layer was described, olefin resin may be used. When an olefin resin is used, it is desirable to improve the wettability with the up-conversion layer by modifying the surface. As the surface modification method, for example, a method of irradiating 2J of excimer UV having a wavelength of 172 nm can be used.

[Embodiment 7]
A display device having an up-conversion layer using the liquid up-conversion microcapsule according to Embodiment 7 will be described as follows.

  As shown in FIG. 4, the display device 300 of this embodiment includes an optical switch layer 31, a color filter layer, a light reflection layer 33, and an up-conversion layer 34. The color filter layer is composed of three color filters, a blue color filter layer (B) 321, a green color filter layer (G) 322, and a red color filter layer (R) 323. The film containing the liquid up-conversion microcapsules described in Embodiment 1 was selectively printed on the blue color filter layer (B) 321 and dried to form the up-conversion layer 34. Further, the up-conversion layer 34 may be formed by patterning. By forming an up-conversion layer on the blue color filter layer 321, the reflectance of light in the blue wavelength region can be improved.

  Further, Lumidot CdS-440 quantum dots (manufactured by SIGMA-ALDRICH) may be combined with the up-conversion layer 34 disposed on the blue color filter layer 321. By combining them, light in the near ultraviolet region can be converted to blue by downshifting, and the reflectance of light in the blue wavelength region can be further improved. As a method of combination, a method of mixing quantum dots in the liquid up-conversion layer 34, a method of laminating a prepolymer solution in which quantum dots are dispersed, and polymerizing the pre-polymer layer can be used.

  The same applies to color filter layers other than blue.

  Up to this point, the case where the up-conversion layer is disposed on any of the three color filter layers has been described. However, the up-conversion layer may be disposed only on one color filter. For example, when the amount of blue light is improved by disposing only on the blue color filter layer, it is only necessary to balance the other two colors by reducing the blue area.

  It is also possible to use a light emitting layer instead of the light reflecting layer. When the light emitting layer is used, the transmittance of light in the blue wavelength region can be further improved by forming an up-conversion layer on the blue color filter layer.

  Another example of a display device having an up-conversion layer using liquid up-conversion microcapsules will be described with reference to FIG. The display device 400 includes an optical switch layer 41, a color filter layer, a light reflection layer 43, and an up-conversion layer 44. The color filter layer was disposed between the up-conversion layer 44 and the light reflecting layer 43 and between the up-conversion layer 44 and the optical switch layer 41. The color filter layers disposed between the up-conversion layer 44 and the light reflecting layer 43 are a blue color filter layer (B) 421, a green color filter layer (G) 422, and a red color filter layer (R) 423. The three color filters are used.

  The color filter disposed between the up-conversion layer 44 and the optical switch layer 41 has a function of absorbing light in a wavelength region that is not required. For example, the color filter layer 424 disposed on the up-conversion layer 44 disposed on the blue color filter layer 421 has a function of absorbing light in the red wavelength region emitted from the downshifting layer. With such a configuration, the color purity of the display device can be further improved.

  As mentioned above, although Embodiment 1 to Embodiment 7 was specifically described, the present invention is not limited to them. Embodiments obtained by appropriately combining the technical means disclosed in each of the seven embodiments described above are also included in the technical scope of the present invention.

  In addition, embodiment disclosed this time is an illustration in all the points, Comprising: It does not become the basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Moreover, all the changes within the meaning and range equivalent to a claim are included.

DESCRIPTION OF SYMBOLS 1 PVA solution 2 Liquid up-conversion mixture 3 Liquid up-conversion microcapsule 11, 21 Light-receiving surface side protective layer 12, 22 Light-receiving surface side sealing layer 13, 23 Solar cell 14, 24, 34, 44 Up-conversion layer 15, 25 Back surface side sealing layer 16, 26 Back surface protective layer 27 Up-conversion film sealing layer 31, 41 Optical switch layer 321, 322, 323, 421, 422, 423, 424, 425, 426 Color filter layer 33, 43 Light reflecting layer 100, 200 Solar cell module 300, 400 Display device

Claims (5)

Forming an up-conversion mixture;
A method for forming a liquid upconversion microcapsule comprising a stirring step of mixing and stirring a solvent and an upconversion liquid. From the light receiving surface side, a solar cell module having a light receiving surface side protective layer, a solar battery cell, a back surface side sealing layer, and a back surface protective layer in this order,
The solar cell module which has an up-conversion layer using the liquid up-conversion microcapsule formed by the method of Claim 1 in the back surface side of the said photovoltaic cell.   The solar cell module of Claim 2 which has the said up-conversion layer between the said photovoltaic cell and the said back surface side sealing layer. Between the solar cell and the back surface protective layer,
The solar cell module of Claim 2 which has the said back surface side sealing layer, the said up-conversion layer, and an up-conversion layer sealing layer. A display device having at least an optical switch layer, a color filter layer, and a reflective layer,
The display apparatus which has an up-conversion layer using the liquid up-conversion microcapsule formed by the method of Claim 1 on the opposite side to the said reflection layer of the said color filter layer.