WO2013094033A1 - 太陽電池の製造方法 - Google Patents
太陽電池の製造方法 Download PDFInfo
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- WO2013094033A1 WO2013094033A1 PCT/JP2011/079649 JP2011079649W WO2013094033A1 WO 2013094033 A1 WO2013094033 A1 WO 2013094033A1 JP 2011079649 W JP2011079649 W JP 2011079649W WO 2013094033 A1 WO2013094033 A1 WO 2013094033A1
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- electrode
- thickness
- printing
- solar cell
- photoelectric conversion
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Definitions
- the present invention relates to a method for manufacturing a solar cell.
- the solar cell includes an electrode on the main surface of the photoelectric conversion unit in order to collect carriers generated by light reception.
- Such an electrode is required to suppress the resistance of the electrode itself, the contact resistance between the electrode and the photoelectric conversion unit, the contact resistance between the electrode and the wiring material, and the like.
- Patent Documents 1 and 2 disclose a method for manufacturing a solar cell in which electrodes are formed by repeating screen printing of a conductive paste a plurality of times.
- the unevenness of the electrode surface can be reduced, and in particular, the resistance of the electrode itself can be lowered.
- further improvement in photoelectric conversion efficiency is required.
- a method for manufacturing a solar cell according to an aspect of the present invention is a method for manufacturing a solar cell including an electrode on a main surface of a photoelectric conversion unit, and includes a plate making having an opening corresponding to the shape of the electrode, and a squeegee. And a step of printing the constituent material of the electrode on the main surface in a plurality of times, and in the first printing step at least the first of the steps, the electrode is formed using a plate making with a plate thickness of 20 ⁇ m to 40 ⁇ m. The component material is printed.
- a solar cell having good photoelectric conversion characteristics can be provided.
- FIG. 1 It is the top view which looked at the solar cell which is an example of embodiment of this invention from the light-receiving surface side. It is a figure which shows the AA line cross section of FIG. It is a figure which shows the principle of the screen printing method in an example of embodiment of this invention. It is a figure which shows the principle of the screen printing method in an example of embodiment of this invention. It is the B section enlarged view of FIG.
- FIG. 1 is a plan view of a solar cell 10 manufactured by a manufacturing method that is an example of an embodiment of the present invention, as viewed from the light-receiving surface side.
- FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and shows a cross section obtained by cutting the solar cell 10 in the thickness direction perpendicular to the direction in which the fingers 21 extend.
- the solar cell 10 is formed on the photoelectric conversion unit 11 that generates carriers by receiving light, the light-receiving surface electrode 20 formed on the light-receiving surface of the photoelectric conversion unit 11, and the back surface of the photoelectric conversion unit 11.
- a back electrode (not shown).
- the back surface electrode can be configured to include a finger and a bus bar, which will be described later, similarly to the light receiving surface electrode 20. Or it is good also as a structure which has metal thin films, such as silver (Ag) formed in the substantially whole area on the back surface.
- the “light-receiving surface” means a main surface on which sunlight mainly enters from the outside of the solar cell 10. For example, more than 50% to 100% of the sunlight incident on the solar cell 10 enters from the light receiving surface side.
- the “back surface” means a main surface opposite to the light receiving surface. On the back surface, the influence of the light-shielding loss on the photoelectric conversion characteristics is less than that of the light receiving surface, so that the back electrode can be formed in a larger area than the light receiving surface electrode 20. In other words, the surface having the large electrode area among the main surfaces is the back surface.
- the photoelectric conversion unit 11 includes a substrate made of a semiconductor material such as crystalline silicon (c-Si), gallium arsenide (GaAs), or indium phosphorus (InP).
- the photoelectric conversion unit 11 has a light-transmitting property such as an i-type amorphous silicon layer, a p-type amorphous silicon layer, and tin-doped indium oxide (ITO) on the light-receiving surface of an n-type single crystal silicon substrate.
- a transparent conductive layer made of a conductive oxide.
- an i-type amorphous silicon layer, an n-type amorphous silicon layer, and a transparent conductive layer are sequentially provided on the back surface of the n-type single crystal silicon substrate.
- the photoelectric conversion unit 11 is not limited to this configuration, and various configurations can be adopted.
- the light receiving surface of the photoelectric conversion unit 11 has a texture structure (not shown).
- the texture structure is a surface uneven structure that suppresses surface reflection and increases the light absorption amount of the photoelectric conversion unit 11.
- the uneven height of the texture structure is preferably 1 ⁇ m to 15 ⁇ m, and particularly preferably 5 ⁇ m to 10 ⁇ m.
- the texture structure there is a pyramidal (quadrangular pyramid or quadrangular pyramid-shaped) uneven structure obtained by performing anisotropic etching on the light receiving surface of a substrate made of single crystal silicon having a (100) plane. It can be illustrated.
- a concavo-convex structure obtained by performing isotropic etching on the light receiving surface of a substrate made of crystalline silicon may be used.
- the texture structure is preferably provided also on the back surface of the photoelectric conversion unit 11.
- the light-receiving surface electrode 20 (hereinafter referred to as electrode 20) includes, for example, a plurality (for example, 50) of fingers 21 and a plurality (for example, two) of bus bars 22.
- the finger 21 is a thin wire electrode formed over a wide range on the light receiving surface in order to collect carriers generated by the photoelectric conversion unit 11.
- the bus bar 22 is an electrode that collects carriers from the fingers 21, and all the fingers 21 are electrically connected.
- a wiring material is connected to the bus bar 22 when the solar cell 10 is modularized.
- two bus bars 22 are arranged in parallel with each other at a predetermined interval, and a plurality of fingers 21 are arranged so as to intersect therewith.
- the finger 21 includes a first finger 21 a that extends from each of the bus bars 22 toward the edge of the light receiving surface, and a second finger 21 b that connects the two bus bars 22.
- Both the finger 21 and the bus bar 22 are preferably formed using a conductive paste described later, and include a binder resin and a conductive filler.
- the finger 21 has a laminated structure.
- the finger 21 has, for example, a first conductive layer 23 formed directly on the light receiving surface and a second conductive layer 24 formed on the first conductive layer 23.
- the bus bar 22 preferably includes a first conductive layer 23 and a second conductive layer 24.
- the finger 21 and the bus bar 22 may have a laminated structure having three or more layers.
- the thickness of the finger 21 is preferably 20 ⁇ m to 100 ⁇ m.
- the thickness t 23 of the first conductive layer 23 is 5 ⁇ m to 35 ⁇ m, more preferably 10 ⁇ m to 30 ⁇ m, and particularly preferably 15 ⁇ m to 25 ⁇ m.
- the thickness t 24 of the second conductive layer 24 is particularly preferably equal to the thickness t 23 from the viewpoint of productivity and the like.
- the thicknesses t 23 and t 24 are average values of values measured by cross-sectional observation using a scanning electron microscope (SEM).
- the thickness of the bus bar 22 is preferably equal to that of the finger 21.
- the width W 21 of the finger 21 is preferably 30 ⁇ m to 150 ⁇ m from the viewpoint of reducing the light shielding loss. As the distance from the bus bar 22 increases, the width W 21 may be narrowed. In this case, the finest width W 21 is preferably 30 ⁇ m to 80 ⁇ m.
- the width of the bus bar 22 is preferably 0.05 mm to 1.5 mm, for example.
- FIG. 5 is an enlarged view of part B of FIG. 3 and shows the dimensions and the like of the screen plate 30.
- the photoelectric conversion unit 11 is manufactured by a known method.
- the electrodes 20 finger 21 and bus bar 22
- the electrodes 20 are formed on the light receiving surface.
- a back surface electrode it can form by the screen printing method similarly to the electrode 20, and can also form by another method.
- the back electrode is formed by a screen printing method, it is preferable that the back electrode be formed in a larger area than the electrode 20 by a single printing process.
- the electrode 20 is formed in a plurality of times using a plate making and squeegee 40.
- the method using plate making and the squeegee 40 is a kind of stencil printing method and belongs to the screen printing method.
- a screen plate 30 illustrated in FIGS. 3 to 5 or a metal mask plate (not shown) can be used as the plate making.
- the screen plate 30 is used as plate making will be described.
- the screen plate 30 having the opening 34 corresponding to the shape of the electrode 20 and the squeegee 40 are used on the light receiving surface of the photoelectric conversion unit 11.
- the ink 50 containing the constituent materials (binder resin and conductive filler) of the electrode 20 is transferred. More specifically, the ink 50 is placed on the screen plate 30 in which the opening 34 is formed only in the portion to be transferred, and the ink 50 is filled in the opening 34 by sliding the squeegee 40. Subsequently, when the portion of the screen plate 30 through which the squeegee 40 passes is separated from the light receiving surface, the ink 50 is ejected from the opening 34 and transferred onto the light receiving surface. After this printing process is repeated a plurality of times, the stacked ink 50 is solidified by heating or the like to form the electrode 20. In the present embodiment, off-contact printing will be described, but on-contact printing may be applied.
- the screen plate 30 includes a mesh 31 that is a woven fabric or the like that transmits the ink 50 and a frame 32 on which the mesh 31 is stretched.
- the mesh 31 is provided with a mask material 33 corresponding to a region on the light receiving surface where the ink 50 is not desired to be applied. That is, the screen plate 30 allows the ink 50 to pass through only the opening 34 which is a portion of the mesh 31 that is not masked by the mask material 33.
- the screen plate 30 has a pattern of openings 34 corresponding to the shapes of the fingers 21a and 21b and the bus bar 22, respectively.
- the material, wire diameter, number of meshes, opening, opening rate, etc. of the mesh 31 are selected according to the width, thickness, etc. of the electrode 20 to be formed.
- the material of the mesh 31 is, for example, a resin fiber such as polyester or a metal wire such as stainless steel.
- the wire diameter of the mesh 31 is selected according to the thickness of the electrode 20 to be formed.
- the number of meshes is selected according to the strength of the mesh 31 and the definition of the electrode 20 to be formed.
- the opening is selected according to the particle size of the conductive filler contained in the ink 50, and is generally preferably at least twice the particle size.
- the opening rate is selected according to the thickness of the electrode to be formed, the sloping width, and the like.
- the material of the mesh 31, the wire diameter, the number of meshes, the opening, the opening rate, and the like are selected depending on the composition of the ink 50, printing conditions, and the like.
- a photosensitive emulsion is usually used.
- the emulsion is selected according to the resolution, exposure sensitivity, and the like.
- a diazo or stilbazolium material is used.
- a metal foil can be used.
- the emulsion is applied, for example, on a mesh 31 stretched on a frame 32, and becomes a mask material 33 through an ultraviolet exposure process and an unexposed part removal process.
- the squeegee 40 is made of a material suitable for spreading the ink 50 on the screen plate 30.
- the squeegee 40 is preferably composed of an elastic body having solvent resistance.
- urethane rubber or the like is suitable.
- the shape of the squeegee 40 is not particularly limited, but a flat squeegee is preferable.
- the ink 50 is a fluid fluid paste.
- examples of the ink 50 include a heat curing type that is solidified by heating at 200 ° C. or less, an ultraviolet curing type that is solidified by ultraviolet irradiation, and a baking type that is solidified by heating at about 400 ° C. to 1000 ° C.
- Particularly suitable as the ink 50 is a heat-curing type conductive paste in which a binder resin and a conductive filler are mixed in a solvent.
- the solvent for example, organic solvents such as alcohols, glycol ethers and hydrocarbons, or mixed solvents thereof are used.
- binder resin for example, a cellulose resin, an epoxy resin, an acrylic resin, a urethane resin, a silicone resin, or a mixed resin thereof is used.
- conductive filler for example, metal particles such as silver (Ag), copper (Cu), nickel (Ni), carbon, or a mixture thereof is used.
- squeegee angle, squeegee speed, squeegee printing pressure, and clearance which is the distance between the screen plate 30 and the photoelectric conversion unit 11, are listed as main parameters for determining printing conditions.
- the squeegee angle is an angle formed by the screen plate 30 and the squeegee 40 with respect to the traveling direction of the squeegee 40.
- the squeegee angle affects the ejectability of the ink 50. Normally, the smaller the angle, the greater the amount of ink 50 ejected. However, if the squeegee angle is too small, the scraping property of the ink 50 is deteriorated, and therefore, approximately 50 ° to 80 ° is preferable, and approximately 60 ° to 70 ° is particularly preferable.
- the squeegee speed is a speed at which the squeegee 40 is moved.
- the squeegee speed is preferably set to about 20 to 200 mm / sec from the viewpoint of printing resolution.
- the squeegee printing pressure is a pressure applied to the squeegee 40. If the squeegee printing pressure is too low, variations in the ejection amount of the ink 50 are likely to occur. On the other hand, if the squeegee printing pressure is too high, the ink 50 is deeply scraped and the transfer amount of the ink 50 is greatly reduced. Therefore, squeegee printing pressure is preferably about 2 ⁇ 6kgf / cm 2, about 3 ⁇ 5kgf / cm 2 is particularly preferred.
- the clearance is a parameter related to plate separation, and is preferably set to about 1/1000 to 1/300 of the inner dimension of the frame 32 from the viewpoint of good plate separation property and suppression of a decrease in screen tension.
- the ink 50 is printed on the light receiving surface in a plurality of times. Then, the electrode 20 having a laminated structure is formed. In the case of the electrode 20 having a two-layer structure, two printing steps are performed.
- the first printing process which is the first printing process
- printing is performed using a screen plate 30 having a plate thickness t 30 of 20 ⁇ m to 40 ⁇ m.
- the first printing step is a step of printing the ink 50 directly on the light receiving surface of the photoelectric conversion unit 11, and the first conductive layer 23 is printed by this step.
- the second printing process which is the second printing process, for example, printing is performed using the same screen plate 30 as in the first printing process.
- the second printing step is a step of printing the ink 50 on the first conductive layer 23 printed in the first printing step, and the second conductive layer 24 is printed by this step.
- the plate thickness t 30 is the screen plate 30 obtained by adding the thickness t 31 which is the thickness of the mesh 31 and the thickness t 33 of the mask material 33 (hereinafter referred to as emulsion thickness t 33 ). Is the total thickness.
- the opening width W 34 of the opening 34 is selected according to the width of the electrode 20. In the case of the finger 21, for example, the opening width W 34 is 30 ⁇ m to 150 ⁇ m, and in the case of the bus bar 22, for example, the opening width W 34 is 0.5 mm to 1.5 mm.
- the dimensions such as t 30 , t 31 , t 33 , and W 34 mean average values unless otherwise specified.
- the transferred ink 50 varies depending on the printing conditions. Therefore, the thickness t 23 of the first conductive layer 23 is made thinner than BanAtsu t 30.
- the screen plate 30 used in the first printing step further preferably has a plate thickness t 30 of 25 ⁇ m to 40 ⁇ m, particularly preferably 25 ⁇ m to 38 ⁇ m. If the plate thickness t 30 in the first printing step is within this range, the contact resistance between the photoelectric conversion unit 11 and the electrode 20 is kept low while the electrode 20 is thinned to sufficiently reduce the amount of conductive paste used. be able to.
- the screen plate 30 used in the first printing step is preferably an emulsion thickness t 33 is 10 ⁇ m or less.
- the thickness t 31 has a limit in thinning from the viewpoint of durability of the screen plate 30. Therefore, a thin plate thickness t 30 such as 20 ⁇ m to 40 ⁇ m can be realized mainly by reducing the emulsion thickness t 33 .
- the emulsion thickness t 33 is preferably 2 ⁇ m or more. When the emulsion thickness t 33 is less than 2 ⁇ m, it is difficult to control the thickness, and the uniformity of the emulsion thickness t 33 may be impaired. That is, in the first printing step, the emulsion thickness t 33 is preferably 2 ⁇ m to 10 ⁇ m. Particularly preferably, it is 2 ⁇ m to 7 ⁇ m.
- the second printing step may be used a screen plate 30 thinner plate thickness t 30 than the first printing step, but as described above, the same screen plate as the first printing process in view of productivity and the like 30 Is preferably used.
- the solar cell 10 which has low resistance loss and a favorable fill factor (FF) is obtained.
- FF fill factor
- the resistance of the electrode 20 itself can be reduced as the thickness of the electrode 20 is increased.
- the plate thickness t 30 of the screen plate 30 is reduced to 40 ⁇ m or less. Normally, the resistance loss increases as the electrode thickness is reduced.
- the printing pressure is transmitted to the interface between the photoelectric conversion unit 11 and the electrode 20 by greatly reducing the plate thickness t 30 of the screen plate 30 to 20 ⁇ m to 40 ⁇ m.
- the contact resistance at the interface is greatly reduced. That is, when the thickness of the transferred ink 50 is reduced, the force applied from the squeegee 40 is not absorbed by the ink 50 but is transmitted to the photoelectric conversion unit 11 and the adhesion between the photoelectric conversion unit 11 and the electrode 20 is improved.
- the printing pressure in the second printing process is also easily transmitted to the interface between the photoelectric conversion unit 11 and the electrode 20. Further, the ink 50 can easily enter the concave portion of the texture structure.
- the solar cell 10 obtained by the said manufacturing method has low contact resistance of the photoelectric conversion part 11 and the electrode 20, and thins the thickness of the electrode 20 and implement
- the thickness of the electrode 20 can be reduced, the stress applied to the photoelectric conversion unit 11 with the thermal expansion and contraction of the electrode 20 can be reduced, and the photoelectric conversion unit 11 can be thinned.
- the manufacturing cost it is possible to reduce the manufacturing cost by reducing the amount of the conductive paste while maintaining the low resistance loss. Further, while maintaining the low resistance loss, the fingers 21 can be further thinned to reduce the light shielding loss. By repeating the screen printing process a plurality of times, the surface unevenness of the electrode 20 is reduced, and for example, the contact resistance between the bus bar 22 and the wiring material can be reduced.
- a photoelectric conversion part for evaluation is produced by the following procedure. Note that the same photoelectric conversion unit is used in all examples and comparative examples.
- a clean n-type single crystal silicon substrate (hereinafter referred to as a substrate) is prepared by anisotropically etching the (100) plane using an aqueous potassium hydroxide (KOH) solution to form a texture structure on the light receiving surface and the back surface.
- KOH potassium hydroxide
- the substrate is placed in a vacuum chamber, and an i-type amorphous silicon film and an n-type amorphous silicon film are sequentially formed on the back surface of the substrate by a CVD (Chemical Vapor Deposition) method.
- CVD Chemical Vapor Deposition
- silane gas (SiH 4 ) is used as a source gas.
- silane (SiH 4 ), hydrogen (H 2 ), and phosphine (PH 3 ) are used as source gases.
- an i-type amorphous silicon film and a p-type amorphous silicon film are sequentially formed by CVD.
- diborane (B 2 H 6 ) is used as a source gas instead of PH 3 .
- a TCO (Transparent Conductive Oxide) layer containing indium oxide as a main component is formed on the n-type amorphous silicon film and the p-type amorphous silicon film by sputtering.
- the photoelectric conversion portion having the layer structure of TCO layer / i-type amorphous silicon film / p-type amorphous silicon film / substrate / i-type amorphous silicon film / n-type amorphous silicon film / TCO layer is obtained. Produced.
- a light receiving surface electrode is formed on the light receiving surface of the produced photoelectric conversion unit, and a back electrode is formed on the back surface of the photoelectric conversion unit.
- the light-receiving surface electrode has two bus bars and 50 fingers orthogonal to the bus bars.
- the following screen plate, squeegee, and conductive paste are prepared. The screen printing process is repeated twice. In the first and second printing steps, the same screen plate, squeegee and conductive paste are used, and the printing conditions shown below are the same. Subsequently, a part of the solvent of the conductive paste transferred by the temporary drying step (150 ° C. ⁇ 15 minutes) is removed.
- the back electrode has two bus bars and 250 fingers orthogonal to the bus bars, and is formed by a single printing process.
- the back electrode is printed in the same manner as in the first printing process of the light receiving surface electrode, except that the pattern of the openings of the screen plate is different. Thereafter, the solvent of the conductive paste transferred by the main drying step (200 ° C. ⁇ 60 minutes) is removed, and the binder resin is thermally cured to form the light receiving surface electrode and the back surface electrode.
- the thickness of the 1st conductive layer (electrode) and the fill factor (FF) were evaluated.
- the evaluation results are shown in Table 1 together with the dimensions of the screen plate used for printing the light receiving surface electrode. Note that the thickness of the electrode is approximately twice the thickness of the first conductive layer.
- Examples 2 to 7 Comparative Examples 1 to 3> A solar cell was produced and evaluated in the same manner as in Example 1 except that the dimensions of the screen plate used for printing the light-receiving surface electrode were changed to those shown in Table 1.
- the mesh used was 400 mesh (hard calender processed product).
- the solar cell of each example showed a high FF, although the electrode thickness was thinner than the solar cells of Comparative Examples 1 to 3. This result is due to the fact that the adhesion between the photoelectric conversion part and the electrode is improved and the contact resistance is greatly reduced by layer printing using a screen plate with a plate thickness of 20 ⁇ m to 40 ⁇ m and an emulsion thickness of 2 ⁇ m to 10 ⁇ m. To do.
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Abstract
Description
本発明は、以下の実施形態に限定されない。また、実施形態において参照する図面は、模式的に記載されたものであり、図面に描画された構成要素の寸法比率などは、現物と異なる場合がある。具体的な寸法比率等は、以下の説明を参酌して判断されるべきである。
図3,4は、スクリーン印刷法の原理を説明するための図である。図5は、図3のB部拡大図であって、スクリーン版30の寸法等を示す図である。
スキージ速度は、スキージ40を移動させる速度である。スキージ速度は、印刷解像性等の観点から、20~200mm/sec程度に設定することが好適である。
スキージ印圧は、スキージ40に加える圧力である。スキージ印圧が低すぎるとインク50の吐出量にばらつきが発生し易くなる。一方、スキージ印圧が高すぎると、インク50の掻き取りが深くなりインク50の転写量が大きく減少する。このため、スキージ印圧は、2~6kgf/cm2程度が好適であり、3~5kgf/cm2程度が特に好適である。
クリアランスは、版離れに関するパラメータであり、良好な版離れ性、スクリーン張力の低下抑制等の観点から、枠32の内寸の1/1000~1/300程度に設定することが好適である。
通常は、電極20の厚みを厚くするほど電極20自体の抵抗を低減できると考えられる。このため従来では、スクリーン版30の版厚t30を40μmより大きくして、1回のスクリーン印刷で転写するインク50の厚みを大きくすることが検討されてきた。しかしながら、このようにスクリーン版30の版厚t30を40μmより大きくしても、期待されるほど抵抗損失を改善することは困難であった。
そこで、上記製造方法では、スクリーン版30の版厚t30を40μm以下と小さくした。通常、電極の厚みを薄くすると抵抗損失が高くなるが、スクリーン版30の版厚t30を20μm~40μmと大幅に薄くしたことにより、光電変換部11と電極20との界面に印圧が伝わり易くなり、当該界面における接触抵抗が大きく低減する。つまり、転写されるインク50の厚みが薄くなると、スキージ40から加わる力がインク50により吸収されず光電変換部11まで伝達されて光電変換部11と電極20との密着性が向上する。また、第2印刷工程における印圧も光電変換部11と電極20との界面に伝わり易くなる。また、インク50がテクスチャ構造の凹部に入り込み易くなる。
このため、上記製造方法により得られる太陽電池10は、光電変換部11と電極20との接触抵抗が低く、電極20の厚みを薄くして良好な光電変換効率を実現する。また、電極20の厚みを薄くできることから、電極20の熱膨張収縮に伴い光電変換部11に加わるストレスを小さくでき、光電変換部11の薄型化を図ることもできる。
評価用の光電変換部を以下の手順で作製する。尚、光電変換部は、全ての実施例・比較例で同じものを用いる。
まず、水酸化カリウム(KOH)水溶液を用いて(100)面を異方性エッチングし、受光面及び裏面にテクスチャ構造を形成した清浄なn型単結晶シリコン基板(以下、基板という)を準備する。続いて、当該基板を真空チャンバ内に設置し、CVD(Chemical Vapor Deposition)法により、当該基板の裏面上にi型非晶質シリコン膜、n型非晶質シリコン膜を順に形成する。i型非晶質シリコン膜の形成工程では、シランガス(SiH4)を原料ガスとする。また、n型非晶質シリコン膜の形成工程では、シラン(SiH4)、水素(H2)、及びホスフィン(PH3)を原料ガスとする。基板の受光面にも、CVDにより、i型非晶質シリコン膜、p型非晶質シリコン膜を順に形成する。p型非晶質シリコン膜の形成工程では、PH3の代わりに、ジボラン(B2H6)を原料ガスとする。
続いて、スパッタリング法により、n型非晶質シリコン膜上、及びp型非晶質シリコン膜上に、酸化インジウムを主成分とするTCO(Transparent Conductive Oxide)層を形成する。
こうして、TCO層/i型非晶質シリコン膜/p型非晶質シリコン膜/基板/i型非晶質シリコン膜/n型非晶質シリコン膜/TCO層の層構造を有する光電変換部を作製した。
受光面電極は、2本のバスバー、及びこれに直交する50本のフィンガーとする。まず、以下に示すスクリーン版、スキージ、及び導電性ペーストを準備する。スクリーン印刷工程は、2回繰り返して行なう。第1・第2印刷工程では、同じスクリーン版、スキージ、及び導電性ペーストを使用し、以下に示す印刷条件も同じとする。続いて、仮乾燥工程(150℃×15分)により転写された導電性ペーストの溶剤の一部を除去する。
裏面電極は、2本のバスバー、及びこれに直交する250本のフィンガーとし、1回の印刷工程により形成する。スクリーン版の開口部のパターンが異なる以外は、受光面電極の第1印刷工程と同様にして裏面電極を印刷する。
その後、本乾燥工程(200℃×60分)により転写された導電性ペーストの溶剤を除去し、バインダ樹脂を熱硬化させて、受光面電極及び裏面電極を形成する。
[スクリーン版・スキージ・導電性ペースト]
メッシュ;400メッシュ(ソフトカレンダー加工品)
マスク材;感光性乳剤
スキージ;ポリウレタン製平スキージ(硬度70度)
導電性ペースト;銀粒子分散エポキシ樹脂
[印刷条件]
スキージ角度;70°
スキージ速度;100mm/sec
スキージ印圧;4kgf/cm2
クリアランス;1.5mm
受光面電極の印刷に使用したスクリーン版の寸法を表1に示すものに変更した以外は、実施例1と同様にして太陽電池の作製及び評価を行なった。尚、メッシュは、400メッシュ(ハードカレンダー加工品)を用いた。
Claims (4)
- 光電変換部の主面上に電極を備えた太陽電池の製造方法であって、
前記電極の形状に対応した開口部を有する製版、及びスキージを用いて、前記電極の構成材を複数回に分けて前記主面上に印刷する工程を備え、
前記工程のうち少なくとも1回目の第1印刷工程では、版厚が20μm~40μmである前記製版を用いて前記構成材を印刷する太陽電池の製造方法。 - 請求項1に記載の太陽電池の製造方法であって、
前記製版は、メッシュと、前記開口部を選択的に形成するマスク材とを含み、
前記第1印刷工程では、前記マスク材の厚みが10μm以下である前記製版を用いて前記構成材を印刷する。 - 請求項2に記載の太陽電池の製造方法であって、
前記第1印刷工程では、前記マスク材の厚みが2μm以上である前記製版を用いて前記構成材を印刷する。 - 請求項1~3のいずれか1項に記載の太陽電池の製造方法であって、
前記工程のうち2回目の第2印刷工程で用いる前記製版の前記版厚は、前記第1印刷工程で用いる前記製版の前記版厚以下である。
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PCT/JP2011/079649 WO2013094033A1 (ja) | 2011-12-21 | 2011-12-21 | 太陽電池の製造方法 |
DE112011106010.6T DE112011106010T5 (de) | 2011-12-21 | 2011-12-21 | Verfahren zum Fertigen einer Solarzelle |
JP2013550007A JP6037135B2 (ja) | 2011-12-21 | 2011-12-21 | 太陽電池の製造方法 |
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CN109804474A (zh) * | 2016-09-23 | 2019-05-24 | 石原化学株式会社 | 太阳能电池单元的制造方法 |
CN114083914A (zh) * | 2021-11-15 | 2022-02-25 | 横店集团东磁股份有限公司 | 一种太阳能电池的印刷设计方法及印刷组件、光伏组件 |
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