WO2011118298A1 - 太陽電池 - Google Patents
太陽電池 Download PDFInfo
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- WO2011118298A1 WO2011118298A1 PCT/JP2011/053398 JP2011053398W WO2011118298A1 WO 2011118298 A1 WO2011118298 A1 WO 2011118298A1 JP 2011053398 W JP2011053398 W JP 2011053398W WO 2011118298 A1 WO2011118298 A1 WO 2011118298A1
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- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/06—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/075—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
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- 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
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
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- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
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- H—ELECTRICITY
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- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0508—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module the interconnection means having a particular shape
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a solar cell.
- the solar cell needs to have a sufficient thickness to absorb incident sunlight.
- recombination occurs while electrons and holes generated by light absorption move a distance corresponding to the thickness of the cell, resulting in a loss of the output current of the solar cell.
- the lifetime of electrons and holes is short, and the above-mentioned problems are serious.
- a technique that achieves both light absorption and current loss reduction is required.
- Patent Document 1 proposes a technique of constructing solar cells by parallel connection of alternately stacked pn junctions as a candidate for a technique that achieves both light absorption and reduction of current loss in solar cells.
- the advantage of this method is that sufficient light absorption can be secured by increasing the number of stacked layers even if the thickness of each p layer and n layer is reduced.
- the technique described in Patent Document 1 has a problem that the layers responsible for light absorption are set to the p layer and the n layer, and the lifetime of the generated minority carriers is inevitably shortened.
- a method of inserting an i layer between the p layer and the n layer the purpose is to improve the quality of the interface, and a film thickness sufficient for light absorption is not ensured.
- An object of the present invention is to realize a reduction in current loss by solving the problem that the minority carrier lifetime in the light absorption layer is short as described above.
- 1stly it is a solar cell, Comprising: 1st p layer, 1st n layer, 1st i layer provided between 1st p layer and 1st n layer, 2nd Provided between the p layer, the second n layer, the second i layer provided between the second p layer and the second n layer, and between the first n layer and the second p layer.
- the first insulating layer is connected to the first p layer via a p layer different from the first p layer, and is connected to the second p layer via a p layer different from the second p layer.
- the first i layer is thicker than the first p layer and the first n layer
- the second i layer is The film thickness is characterized by being larger than the film thickness of the second p layer and the film thickness of the second n layer.
- 2ndly it is a solar cell, Comprising: 1st p layer, 1st n layer, 1st i layer provided between 1st p layer and 1st n layer, 2nd Provided between the p layer, the second n layer, the second i layer provided between the second p layer and the second n layer, and between the first n layer and the second p layer.
- the second i layer is thicker than the n layer, and the second p layer is thicker than the second p layer and the second n layer. That.
- FIG. 1 It is a 6th sectional view showing a manufacturing method of a solar cell concerning Example 1 of the present invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 2 of this invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 3 of this invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 4 of this invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 5 of this invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 6 of this invention. It is sectional drawing which shows the structure of the solar cell which concerns on Example 7 of this invention.
- FIG. 1 is a schematic cross-sectional view of a solar cell structure according to Example 1 of the present invention.
- a normal solar cell has only a single pn junction or a single pin junction, while the solar cell of the present invention has a structure in which a plurality of pin junctions 31 are stacked.
- the film thickness of the i layer 1 in the pin junction 31 is made thicker than the film thickness of the p layer 11 and the n layer 21 in order to obtain the effect described later.
- An insulating film 41 is inserted between adjacent pin junctions 31. Further, there are through electrodes penetrating these stacked pin junctions, and the pin junctions 31 are electrically connected in parallel by the through electrodes.
- a through-hole side surface portion p layer 14 and a through-hole side surface portion n layer 24 provided through the p layer 11, i layer 1, and n layer 21, respectively, are formed on the through hole side surface portion. Therefore, a key-type p layer and an n layer are formed around the i layer 1.
- electrons and holes generated by light absorption in the i layer 1 move in opposite directions due to the built-in electric field generated by the key-type p layer and n layer. That is, electrons move from the i layer 1 to the n layer 21 and further to the through hole side surface n layer 24, while holes move from the i layer 1 to the p layer 11 and further to the through hole side surface p layer 14. .
- the through hole side surface portion p layer 14 and the through hole side surface portion n layer 24 are electrically connected to the through electrodes, respectively.
- the through electrodes are classified into two types depending on whether they are in contact with the through hole side surface p layer 14 or the through hole side surface n layer 24. Here, they are referred to as a p layer side through electrode 51 and an n layer side through electrode 52, respectively. . Electrodes are provided on the front surface or back surface of the solar battery cell, and they are electrically connected to the through electrode.
- an electrode in contact with the p-layer side through electrode 51 is referred to as a p-layer side electrode 53
- an electrode in contact with the n-layer side through electrode 52 is referred to as an n-layer side electrode 54.
- both the p-layer side electrode 53 and the n-layer side electrode 54 are arranged on the back surface of the solar battery cell, both may be arranged on the surface of the cell. May be arranged on the front surface and the other on the back surface. On the front and back surfaces of the cell, regions where no electrode is present are covered with the front surface insulating film 42 or the back surface insulating film 43. In FIG. 1, all layers are depicted as flat films, but may be subjected to texturing for the purpose of reducing reflection or confining light. Further, an antireflection film may be added on the surface insulating film 42.
- FIG. 2 is a schematic view of the solar cell structure according to Example 1 of the present invention as viewed from the back side.
- the p-layer side electrode 53 and the n-layer side electrode 54 are each formed in a comb shape and serve as a connection portion with an external electrode terminal.
- a cross-sectional view taken along line AB in FIG. 2 corresponds to FIG.
- the generated electrons and holes move to the n layer 21 and the p layer 11 by the drift motion and the diffusion motion by the built-in electric field of the pin junction 31, respectively.
- the electrons that have reached the n layer 21 and the holes that have reached the p layer 11 are n by the drift motion and the diffusion motion caused by the built-in electric field generated by the through hole side surface p layer 14 and the through hole side surface n layer 24, respectively. It moves to the layer side through electrode 52 and the p layer side through electrode 51. Electrons and holes that have reached the through electrode move to the n-layer side electrode 54 and the p-layer side electrode 53, respectively, and generate an output current to the outside.
- the insulating film 41 inserted between adjacent pin junctions 31 plays a role of electrical insulation between the p layer 11 in one pin junction 31 and the n layer 21 of the adjacent pin junction 31. In addition, it also provides an interface passivation effect. Similarly, the front surface insulating film 42 and the back surface insulating film 43 function as a passivation film.
- Patent Document 1 The greatest difference between the invention according to Patent Document 1 and the present invention is that the layers mainly responsible for light absorption are the p-layer 11 and the n-layer 21 in the solar cell described in Patent Document 1, whereas It is in the point that it is i layer 1 in a solar cell.
- Patent Document 1 also describes a technique that uses a pin junction instead of a pn junction, but its purpose is to improve the quality of the pin junction interface. Therefore, the i layer is mainly responsible for light absorption. It does not have a sufficient film thickness.
- the solar cell of the present invention is characterized in that the film thickness of the i layer 1 is larger than the film thickness of the p layer 11 and the n layer 21 as described above. It is mainly responsible for absorption.
- the solar cell according to this example includes the first p layer 11, the first n layer 21, and the first provided between the first p layer and the first n layer.
- the first insulating layer 41 provided between the layer and the second p layer is connected to the first p layer via a p layer different from the first p layer, and is different from the second p layer
- the first through electrode 51 connected to the second p layer via the p layer, and the first n layer connected to the first n layer via an n layer different from the first n layer Has a second through electrode 52 connected to the second n layer through a different n layer, and the film thickness of the first i layer is the same as the film thickness of the first p layer and the first film
- the thickness of the second i layer is larger than the thickness of the n layer. And wherein the greater thickness than the n-layer.
- the first through electrode is connected to the first p layer through “a p layer different from the first p layer”, and is connected to the second through the “p layer different from the second p layer”.
- the second through electrode is connected to the first n layer through “an n layer different from the first n layer” and “an n layer different from the second n layer”.
- a key-type n layer can be formed around the i layer 1.
- the film thickness of the first i layer is larger than the film thickness of the first p layer and the film thickness of the first n layer
- the film thickness of the second i layer is the film thickness of the second p layer and By being thicker than the thickness of the second n layer, it is possible to obtain a larger output current than when the p layer or the n layer is responsible for light absorption.
- two structures are assumed as “a p layer different from the first p layer” and “a p layer different from the second p layer”.
- a “p layer different from the first p layer” and a “p layer different from the second p layer” are formed in the independent p layer 14 via the insulating layer 41.
- the technical idea of the present invention encompasses both of these two structures.
- FIG. 3 is a diagram showing a method for manufacturing a solar battery cell according to the first embodiment. Hereafter, based on FIG. 3, the constituent material and manufacturing method of the photovoltaic cell of this invention are demonstrated.
- a film from the front surface insulating film 42 to the back surface insulating film 43 is formed on the substrate 61.
- the material of the substrate 61 is not particularly limited, and for example, a Si substrate, a quartz substrate, a glass substrate, or the like can be used.
- FIG. 3 shows an example of a manufacturing method in the case where the substrate 61 is transparent and both the p-layer side electrode 53 and the n-layer side electrode 54 are arranged on the cell back side. In this case, as shown in FIG. 3A, a surface insulating film 42 is first formed on the substrate 61.
- the manufacturing method differs depending on the type of the substrate 61 and whether the electrode is disposed on the front surface side or the back surface side.
- the substrate 61 when the substrate 61 is not transparent, it is desirable that the substrate 61 is not on the surface side in the final structure of the solar battery cell. For this purpose, it is necessary to either form the back surface insulating film 43 sequentially on the substrate 61, or form the surface insulating surface 42 on the substrate 61 in order, and finally detach the substrate 61. .
- substrate 61 is not shown in the figure from FIG.3 (b) to FIG.3 (f).
- the semiconductor material forming the pin junction 31 of the solar battery cell is not particularly limited, and includes, for example, Si, CdTe, CuInGaSe, InP, GaAs, Ge, and the like. These include various materials such as single crystal, polycrystal, microcrystal, and amorphous. Can take a structure. These semiconductor layers are formed by a film formation method such as a CVD method, a sputtering method, an epitaxy method, or an evaporation method.
- the insulating film 41 As a material of the insulating film 41, a compound of the above semiconductor material such as SiO 2 or SiN (silicon nitride) may be used, or another insulator may be used.
- the insulating layer 41 can be formed by a film forming method such as a CVD method, a sputtering method, an epitaxy method, or a vapor deposition method. Further, when the insulator is a compound of a semiconductor material, the semiconductor layer is oxidized. Alternatively, nitriding can be performed.
- a through hole 62 is formed.
- the through hole 62 is formed by a technique such as laser, photolithography, etching, or the like.
- the through hole needs to penetrate at least from the back surface insulating film 43 to the pin junction 31 immediately below the surface insulating film 42.
- the surface insulating film 42 and the substrate 61 may be further penetrated.
- the through hole 62 is formed by a laser, there is a method of using a film having a barrier property for preventing penetration as the surface insulating film 42 in order not to penetrate the substrate 61.
- the surface insulating film 42 has a two-layer structure, and SiN (silicon nitride) is used as a film in contact with the substrate 61 and SiO 2 is used as a film in contact with the pin junction 31.
- SiN silicon nitride
- SiO 2 is a film having low thermal conductivity, thermal conduction to the substrate 61 is suppressed even when the lower laminated pin junction 31 is heated by a laser.
- the semiconductor material forming the pin junction 31 is Si
- a lower interface state density can be realized by using SiO 2 as a passivation film than when SiN is used as a passivation film.
- SiN plays a role of suppressing diffusion of impurities contained in the substrate 61 into the pin junction 31.
- this laminated structure By using this laminated structure, it is possible to simultaneously realize three points of prevention of through-hole formation in the substrate 61, good interface passivation, and prevention of diffusion of impurities in the substrate 61. Note that it is desirable to form the through hole in a vacuumed space so that no flash is generated when the through hole is formed.
- a p-layer side through electrode 51 and an n-layer side through electrode 52 are formed.
- the through electrode is formed by a sputtering method, a vapor deposition method, a film forming method such as a CVD method, or a printing method.
- a metal or a semiconductor doped with an impurity at a high concentration in order to reduce electric resistance is used.
- the p layer side through electrode 51 and the n layer side through electrode 52 are respectively an acceptor and a donor. Must be included.
- the work function of the material of the p-layer side through electrode 51 is desirably smaller than the work function of the material of the n-layer side through electrode 52, and when the through electrode is a semiconductor, It is desirable to use a p-type semiconductor as the p-layer side through electrode 51 and an n-type semiconductor as the n-layer side through electrode 52, respectively.
- the n layer side through electrode 52 and the p layer side through electrode 51 are generated by light absorption in the i layer 1 and then the electrons that have reached the n layer 21 and the holes that have reached the p layer 11, respectively. It is possible to increase the built-in electric field that causes the drifting motion to drift.
- the through electrode is formed before the through hole side surface p layer and the through hole side surface n layer, but before the through electrode is formed, ion implantation, vapor phase diffusion method,
- the through hole side surface portion p layer and the through hole side surface portion n layer may be formed by an impurity diffusion method such as a solid phase diffusion layer, and then the through electrode may be formed. In this case, it is not necessary for the material of the through electrode to contain an acceptor or a donor.
- the electrode is formed at the same time as the through electrode is formed, or separately formed after the through electrode is formed as shown in FIG.
- As the electrode material a metal having a low electric resistance is desirable.
- the material of the p-layer side electrode 53 and the material of the n-layer side electrode 54 may be the same or different.
- the electrodes are generally formed by a printing method, but may be formed by a film forming method such as a sputtering method, a vapor deposition method, or a CVD method.
- the width of the electrode is arbitrary, but when the electrode is formed on the surface of the solar battery cell, it is necessary to determine the optimum electrode width in consideration of the shielding loss by the electrode and the electric resistance of the electrode.
- the electrode width should be made as wide as possible within the range where the p-layer side electrode 53 and the n-layer side electrode 54 are in contact with each other and there is no fear of short-circuiting. It is possible to simultaneously reduce the electrical resistance of the electrode and improve the reflectance of the incident light on the back surface of the cell.
- the electrode extending in the vertical direction in FIG. 2 and the electrode extending in the horizontal direction in FIG. 2 may have different electrode materials and electrode widths.
- heat treatment or plasma treatment for improving the crystallinity or film quality of each film or for improving the quality of the interface with the adjacent film may be added as appropriate.
- FIG. 4 is a schematic cross-sectional view of the solar cell structure according to Example 2 of the present invention.
- the feature of this structure is that in the solar battery cell of Example 1, the through-hole side surface portion p layer 14 and the through-hole side surface portion n layer 24 connected to different pin junctions 31 are electrically insulated from each other by the insulating film 41. It is not done.
- the contact area with the n-layer side electrode 54 can be increased as compared with the case of the first embodiment, and as a result, the contact resistance of the contact portion can be reduced.
- the operation principle of the solar battery cell of the second embodiment is the same as that of the first embodiment. Electrons and holes generated by light absorption in the i layer 1 move in opposite directions, so that the output current is reduced. appear.
- the through hole side surface portion p layer 14 and the through hole side surface portion n layer 24 are formed by the CVD method before forming the through electrode in the manufacturing process of the structure of Example 1. What is necessary is just to form by film-forming methods, such as a sputtering method, an epitaxy method, and a vapor deposition method.
- the structure of the second embodiment has a structure in which the p layer 11 and a part of the n layer 21 are partially diffused by the impurity diffusion in the manufacturing process of the first embodiment.
- the step of forming part of the hole side surface p layer 14 can be omitted.
- the through-hole side surface n-layer 24 and the through-hole side surface p-layer 14 are formed by the film forming method, so that it is easy to increase the film thickness compared to the first embodiment. It is.
- the structure of Example 2 achieves high rectification of the pn junction formed by the n layer 24 and the p layer 14 on the side surface of the through hole and the n layer 21 and the p layer 11 in the pin junction. There is an advantage that can be.
- FIG. 5 is a schematic cross-sectional view of the solar cell structure according to Example 3 of the present invention.
- this structure has no through-hole side surface p-layer 14 and through-hole side surface n-layer 24, and a metal or semiconductor having a different Fermi level as a through-electrode. Is in the point of using.
- the through-hole p-type electrode 15 is formed of a material having a lower Fermi level
- the through-hole n-type electrode 25 is formed of a material having a higher Fermi level.
- the heat treatment for impurity diffusion necessary for forming the through hole side surface portion p layer 14 and the through hole side surface portion n layer 24 can be omitted.
- a material whose electrical or optical properties are deteriorated by the heat treatment can be used as the material of the layer formed prior to the heat treatment, such as the pin junction 31.
- the operating principle of the solar battery cell of the third embodiment is the same as that of the first embodiment, and the Fermi level of the through hole p-type electrode 15 and the through hole n-type electrode 25 is different. The electrons and holes generated in the above move in opposite directions to generate an output current.
- the invention according to the third embodiment has an advantage that the heat treatment for forming the through-hole side surface portion p layer 14 and the through-hole side surface portion n layer 24 is not necessary.
- FIG. 6 is a schematic diagram of the structure of a solar battery cell according to Example 4 of the present invention.
- the feature of this structure is that in the solar cell of Example 1, the semiconductor material constituting the stacked pin junction 31 is not a single substance but a substance having a plurality of different band gaps. is there.
- the order of lamination is set so that the material with the larger band gap is closer to the sunlight incident surface.
- the number of stacks and the number of species need not match. That is, a plurality of layers made of one kind of substance may exist.
- the solar cell of Example 4 exhibits the following light absorption characteristics.
- the number of pin junctions 31 stacked is expressed as T, and the band gap (Eg) of the constituent material of each layer is expressed as Eg1, Eg2,.
- Eg1 ⁇ Eg2 ⁇ ... ⁇ EgT.
- EL energy of light
- the energy of light is expressed as EL
- light satisfying the condition of EL ⁇ Eg1 is absorbed by the first pin junction 32 from the cell surface
- the second pin junction 33 from the cell surface is absorbed by the first pin junction 32.
- light that satisfies the condition of EL ⁇ Eg2 is absorbed.
- the fourth embodiment it is possible to simultaneously realize absorption in a wide wavelength range in a solar battery cell, suppression of hot carrier generation, and reduction in variation in output current.
- sunlight contains light in a wide wavelength range, and in order to improve the efficiency of the solar cell, a technology that absorbs light in such a wide wavelength range as much as possible is necessary.
- generation of hot carriers is suppressed.
- the amount obtained by subtracting Eg from EL is given to electrons and holes as excess energy.
- Such carriers are in a higher energy state than the conduction band edge or the valence band edge, and are called hot carriers.
- the excess energy of hot carriers is usually dissipated as heat before the carriers reach the electrode.
- This heat is not only a waste that cannot be taken out as electric power, but also heats the semiconductor material constituting the cell and deteriorates its characteristics.
- the output voltage of the solar cell decreases as the temperature increases.
- there are many effects of temperature on solar cell characteristics such as an increase in the probability of carrier scattering due to temperature rise. Therefore, in order to improve the characteristics of the solar cell, it is important how to suppress the generation of hot carriers.
- the variation in output current is more important in the characteristics of the modules in which the cells are connected in series, rather than the characteristics of the single solar cell. If there is a variation in the output current of each cell, the output current as a module is aligned to its minimum value, and therefore the variation is reduced by the variation. Therefore, a technique for reducing variations in the output current of the solar battery cells is necessary for improving the module efficiency.
- the first example is a case where all the pin junctions in the solar cell structure of the first embodiment are made of a material having a band gap corresponding to a relatively long wavelength side in the sunlight spectrum.
- the second example is a case where all the pin junctions in the solar cell structure of the first embodiment are made of a material having a band gap corresponding to a relatively short wavelength side in the sunlight spectrum.
- the third example is a so-called tandem solar cell structure in which a plurality of pn junctions or pin junctions are connected in series.
- the first example is compared with the fourth embodiment.
- the difference between the two is that suppression of hot carrier generation can be realized only in the case of the fourth embodiment.
- the reason is that in the first example, since the band gaps of the constituent materials of all pin junctions are relatively small, the generation of hot carriers due to short wavelength components contained in sunlight is unavoidable.
- the second example is compared with the fourth embodiment.
- the difference between the two is that absorption in a wide wavelength range can be realized only in the case of the fourth embodiment.
- the reason is that, in the second example, since the band gaps of the constituent materials of all pin junctions are relatively large, long wavelength components contained in sunlight cannot be absorbed.
- the third example is compared with the fourth embodiment.
- the difference between the two is that the variation in the output current can be reduced only in the case of the fourth embodiment.
- the reason is described below.
- light absorption in a part of the stacked pn junctions or pin junctions is caused by a deviation in film thickness or film composition.
- the other layers can compensate for their light absorption.
- variations in the output currents of the individual pn junctions or pin junctions become variations in the total output current of the solar cells. .
- the fourth embodiment since the pn junction or the pin junction is connected in parallel, the total output current is the sum of the output currents of the respective pin junctions. For this reason, even if there is a variation in the output current of each pin junction due to the variation in light absorption, the variation in the total output current is compensated. Therefore, unlike the above three comparative examples, the fourth embodiment can simultaneously achieve absorption in a wide wavelength range, suppression of hot carrier generation, and reduction in variation in output current. is there.
- layers having different band gaps may be appropriately formed as described above when forming the pin junction 31 in the manufacturing process of the structure of the first embodiment.
- materials having different band gaps materials having different elemental compositions, materials having the same composition but different crystal states, materials having the same composition and crystal state, and materials having different band gaps due to the quantum confinement effect described in Example 5, Etc. can be used.
- FIG. 7 is a diagram showing the structure of the solar cell in Example 5.
- the feature of this structure is to include a three-layer stacked structure in which the upper and lower sides of the i layer 1 are sandwiched between the insulating films 44 instead of the light absorbing layer in the solar battery cell of Example 3 as the single i layer 1. Is to do.
- the condition of the insulating film 44 is that it becomes a barrier film that forms an energy barrier against both electrons and holes in the i layer 1.
- the insulating film 44 is referred to as a barrier film 44.
- the i layer 1 is made of Si, SiO 2 , SiN (silicon nitride), SiC (silicon carbide), or the like can be used as the barrier film 44.
- the film thickness of the i layer 1 it is necessary to set the film thickness of the i layer 1 to be sufficiently thin so that a so-called quantum confinement effect occurs in which the band gap of the film has a value different from the band gap of the bulk material. is there.
- m e and m h are effective masses of electrons and holes
- ⁇ is a dielectric constant
- h is Planck's constant
- e is an elementary charge.
- the above formula is expressed in the MKSA unit system.
- the conditions for generating the quantum confinement effect depend on the height of the energy barrier formed by the barrier film 44 and the film thickness of the barrier film 44 in addition to the film thickness of the film to be confined, that is, the i layer 1 here. . In order to obtain quantitative dependency, it is necessary to solve the Schrödinger equation. Qualitatively, the lower the energy barrier formed by the barrier film 44 and the smaller the film thickness of the barrier film 44, the more the quantum confinement.
- Example 4 can also be manufactured by setting the film thickness of the i layer 1 in the pin junction 31 to be laminated to a different value for each layer.
- a structure in which a thin film is sandwiched between insulating films, that is, a so-called quantum well will be described as an example of a structure that exhibits a quantum confinement effect. It is also applicable to structures with different confinement dimensions. Moreover, you may apply the said change not to Example 3 but to the photovoltaic cell of Example 1 and Example 2.
- the film thickness of the i layer 1 confined by the barrier film 44 needs to be thin enough to cause the quantum confinement effect. Therefore, when this is applied to a solar cell, in order to ensure sufficient light absorption, it is common to stack a large number of barrier films 44 and i layers 1 alternately to increase the total thickness of the i layers 1. It is. However, as a result of stacking a large number of barrier films 44 and i layers 1, the total film thickness of the barrier film 44 through which electrons and holes pass is also increased, and the electrical resistance is greatly increased. Therefore, it has been impossible in the past to ensure sufficient light absorption and reduce electric resistance in the application of a quantum confinement solar cell.
- the fifth embodiment it is possible to achieve both the above-described sufficient light absorption and reduction of electric resistance.
- a large number of unit structures of p layer 11 -light absorption layer-n layer 21 are stacked, and the total thickness of i layer 1 is increased.
- the part which was the pin junction 31 in Example 1 has a structure including the barrier film 44 in Example 5, it is more generally expressed as p layer 11 -light absorption layer -n layer 21. is doing.
- the barrier films 44 and the i layers 1 are alternately laminated, that is, only a large number of light absorption layers are laminated.
- the structure sandwiched between the p layer 11 and the n layer 21 is a unit structure, and a large number of the unit structures are stacked.
- electrons and holes generated in the light absorption layer can reach the p layer 11 and the n layer 21 only after passing through all of the stacked light absorption layers.
- electrons and holes can reach the p layer 11 and the n layer 21 if they pass only through the light absorption layer in the unit structure. Therefore, according to the fifth embodiment, the total film thickness of the barrier film 44 through which electrons and holes pass is equal to the film thickness of the barrier film 44 included in the unit structure, and as a result, the output current of the solar cell.
- the fifth embodiment the case where there is one i layer 1 included in the unit structure of the p layer 11 -the light absorption layer-n layer 21 is described, but the number of i layers 1 in the unit structure is arbitrary. It is. As the number of stacked layers is smaller, the film thickness of the barrier film 44 through which electrons and holes pass can be reduced, so that the current loss reduction effect is increased.
- the formation of the absorption layer may be replaced with the formation of the above three-layer laminated film.
- Formation of the barrier film 44 on the i layer 1 may be performed by a film formation method such as a CVD method, a sputtering method, an epitaxy method, or an evaporation method, or may be performed by oxidation or nitridation of the i layer 1. Further, heat treatment or plasma treatment for improving the crystallinity and film quality of the i layer 1 or improving the quality of the interface with the adjacent film may be added as appropriate.
- FIG. 8 is a diagram showing the structure of the solar cell in Example 6.
- the feature of this structure is that a transparent conductive film 55 is inserted between the p layer 11 and the n layer 21 of each pin junction 31 and the adjacent insulating film in the solar cell of the first embodiment.
- the transparent conductive film 55 needs to have a low sheet resistance as compared with any of the p layer 11 and the n layer 21, and preferably has a high transmittance in the wavelength region of sunlight. It is necessary to select the film type and film thickness of the transparent conductive film 55 so as to satisfy the above condition. Moreover, you may apply the said change not to Example 1 but to the photovoltaic cell of Example 2 and Example 3.
- a process of forming the transparent conductive film 55 may be added to the manufacturing process of the structure of the first embodiment.
- the transparent conductive film 55 are oxides containing elements such as In, Zn, Sn, and Ga, and composite oxides thereof, and additives such as fluorine may be added thereto.
- the film formation is performed by a sputtering method, a CVD method, a coating method, a printing method, or the like.
- another film may be inserted between them.
- heat treatment or plasma treatment for improving the crystallinity and film quality of the transparent conductive film 55 or improving the quality of the interface with the adjacent film may be added as appropriate.
- the material of the transparent conductive film 55 is often made of an element different from the semiconductor material constituting the pin junction 31, and in this case, the method for forming the through-hole side surface portion p layer 14 and the through-hole side surface portion n layer 21 As in Example 1, the impurity diffusion method cannot be used. Therefore, in order to generate a built-in electric field for moving electrons and holes in the transparent conductive film 55 in the opposite directions, the through-hole side surface p layer 14 and the through-hole side surface n The layer 24 is formed by a film formation method, or the through-hole p-type electrode 15 and the through-hole n-type electrode 25 are formed as in the third embodiment. It is necessary to take one of the methods of generating the built-in electric field only by the difference in work function of the metal material.
- the series resistance component of the solar battery cell of the first embodiment can be reduced.
- the reason for this is that electrons and holes generated by light absorption need to move in the in-plane direction of the p-layer 11 and the n-layer 21 of the pin junction 31 in the first embodiment. This is because, in No. 6, the transparent conductive film 55 having a sheet resistance lower than that of the p layer 11 and the n layer 21 can be moved in-plane.
- FIG. 9 is a diagram showing the structure of the solar cell in Example 7.
- This structure is a tandem structure in which the solar battery cell of Example 1 of the present invention and the conventional solar battery cell 63, that is, a cell composed of only a single pn junction or a pin junction are connected in series.
- a p-side electrode is formed on the back surface side of the conventional solar cell 63
- an n-layer is formed on the front surface side
- the n-layer and the p-layer side through electrode 51 of the solar cell of the present invention are formed.
- the n-layer side through electrode 52 of the solar battery cell of the present invention is connected to the n-layer side electrode 54 on the cell surface.
- a structure in which the p layer and the n layer are inverted may be used. Moreover, you may use any photovoltaic cell from Example 2 to Example 6 instead of Example 1. FIG. You may form a tunnel junction diode in the connection part of the conventional solar cell 63 and the solar cell of this invention. Below, although the surface insulating film of the conventional solar cell 63 and the back surface insulating film 43 of the solar cell of the present invention will be described as the same film, they may be different from each other.
- the order of stacking of the conventional solar cell 63 and the solar cell of the present invention is the same as that of a general tandem solar cell. It is desirable that the battery be on the sunlight incident surface side. In addition, since the solar cell of the present invention is particularly effective for application to a semiconductor material in which a short carrier lifetime is a problem, the tandem solar cell of Example 7 also has a shorter carrier lifetime. It is desirable to apply the solar cell structure of the present invention to a solar cell made of a material.
- the seventh embodiment it is possible to increase the efficiency of the tandem solar cell.
- the effect of increasing the efficiency is great.
- the problems of the prior art will be described.
- a tandem solar battery since a plurality of solar battery cells are connected in series, the current values flowing through these cells must be aligned. Therefore, when a plurality of cells having different output currents are tandemized, the minimum value of those output currents becomes the entire output current. Therefore, conventionally, tandem solar cells having different output currents are often less efficient than a single cell having a larger output current.
- the output current can be improved by applying the solar cell structure of the present invention to the solar cell having a small output current.
- the output current of the entire tandem solar cell can be improved as compared with the conventional tandem solar cell, a highly efficient tandem solar cell can be realized.
- the p-layer side through electrode 51 penetrates from the lower end of the surface insulating film 42 of the solar cell of the present invention to the lower end of the back surface insulating film 43, and the n-layer side through electrode 52 is The solar cell of the present invention is set so as to penetrate from the upper end of the front surface insulating film 42 to the upper end of the back surface insulating film 43.
- the through-hole is formed up to the upper end of the back surface insulating film 43, and after the material of the p-layer side through-electrode 51 is embedded in the through-hole, the p-layer side through electrode 51 is formed.
- As a method for forming the n-layer side through electrode 52 for example, there is a method in which the barrier film having laser penetration resistance described in the first embodiment is used as the back surface insulating film 43.
- the method of first forming the solar cell of the present invention can be further divided into two methods depending on whether or not the substrate 61 forming the solar cell of the present invention is made of a transparent material.
- the order of film formation is set so that the transparent substrate is disposed on the outermost surface in the final solar cell structure. At that time, the through hole needs to completely penetrate the substrate 61 so that the electrode is exposed on the surface.
- a non-transparent material is used as the substrate 61, it is necessary to add a step of separating the substrate 61 and the solar cell formed thereon.
- a separation method for example, a smart cut method, which is one of SOI (Silicon On Insulator) wafer forming methods, can be applied.
- the layer of the conventional solar cell 63 is formed by a film forming method such as a CVD method, a sputtering method, an epitaxy method, or a vapor deposition method.
- a film forming method such as a CVD method, a sputtering method, an epitaxy method, or a vapor deposition method.
- the above SOI wafer forming method can also be applied to the bonding.
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Abstract
Description
図1は、本発明の実施例1に係る太陽電池セル構造の断面図の概略である。通常の太陽電池セルは、単一のpn接合あるいは単一のpin接合のみを有するが、一方、本発明の太陽電池セルは、複数のpin接合31が積層された構造を有する。ここで、本発明の太陽電池セルの特徴として、pin接合31のうちi層1の膜厚は、後述する効果を得るために、p層11やn層21の膜厚よりも厚くするという点を挙げておく。隣接するpin接合31の間には絶縁膜41が挿入されている。また、これらの積層されたpin接合を貫通する貫通電極が存在し、pin接合31同士は、この貫通電極によって電気的に並列接続される。貫通孔側面部には、図1に示すように、それぞれp層11、i層1、n層21を貫通して設けられる貫通孔側面部p層14および貫通孔側面部n層24が形成され、従って、i層1の周囲に鍵型のp層およびn層が形成される。この結果、i層1での光吸収により発生する電子と正孔とが、鍵型のp層およびn層の生成する内蔵電界により、互いに逆向きに移動する。すなわち、電子はi層1からn層21、さらに貫通孔側面部n層24へと移動し、一方、正孔はi層1からp層11、さらに貫通孔側面部p層14へと移動する。貫通孔側面部p層14および貫通孔側面部n層24は、それぞれ貫通電極と電気的に接続される。貫通電極は、貫通孔側面部p層14と接するか、貫通孔側面部n層24と接するかによって二種類に分けられ、ここではそれぞれp層側貫通電極51、n層側貫通電極52と呼ぶ。太陽電池セルの表面または裏面には電極が設けられ、それらが貫通電極と電気的に接続される。ここでは、p層側貫通電極51と接する電極をp層側電極53、n層側貫通電極52と接する電極をn層側電極54と、それぞれ呼ぶ。図1には、p層側電極53、n層側電極54が、ともに太陽電池セルの裏面に配置された例を示しているが、ともにセルの表面に配置してもよいし、また、一方を表面、もう一方を裏面にそれぞれ配置してもよい。セルの表面および裏面において、電極の存在しない領域は、表面絶縁膜42または裏面絶縁膜43で覆われる。なお、図1では、すべての層が平坦な膜として描かれているが、反射低減や光閉じ込めの目的のためのテクスチャ化の処理を施してもよい。また、表面絶縁膜42上に反射防止膜を追加してもよい。
図4は、本発明の実施例2に係る太陽電池セル構造の断面図の概略である。この構造の特徴は、実施例1の太陽電池セルにおいて、異なるpin接合31と接続される貫通孔側面部p層14および貫通孔側面部n層24とが、絶縁膜41で互いに電気的に絶縁されないということである。
図5は、本発明の実施例3に係る太陽電池セル構造の断面図の概略である。この構造の特徴は、実施例1の太陽電池セルと比較して、貫通孔側面部p層14および貫通孔側面部n層24がなく、また、貫通電極として、フェルミ準位の異なる金属または半導体を用いている点にある。具体的には、フェルミ準位のより低い材料で貫通孔p型電極15を、フェルミ準位のより高い材料で貫通孔n型電極25を、それぞれ形成するということである。
図6は、本発明の実施例4に係る太陽電池セルの構造の概略である。この構造の特徴は、実施例1の太陽電池セルにおいて、積層されるpin接合31を構成する半導体材料を、単一物質にするのではなく、複数の異なるバンドギャップを有する物質にするということである。積層の順番は、バンドギャップが大きい物質ほど太陽光の入射面に近くなるように設定する。積層の数と物質種の数とが一致する必要はない。すなわち、一種類の物質からなる層が複数存在してもよい。また、実施例1でなく、実施例2および実施例3の太陽電池セルに上記変更を適用してもよい。
図7は、本実施例5における太陽電池の構造を示す図である。この構造の特徴は、実施例3の太陽電池セルにおける光吸収層を、単一のi層1とするかわりに、i層1の上下を絶縁膜44で挟んだ三層積層構造を含むようにするということである。上記絶縁膜44の条件は、i層1中の電子と正孔の両方に対するエネルギー障壁を形成するバリア膜となることである。以後、絶縁膜44をバリア膜44と記す。例えば、i層1がSiからなる場合には、バリア膜44として、SiO2、SiN(窒化シリコン)、SiC(炭化シリコン)などを用いることができる。このとき、i層1の膜厚を十分に薄くすることにより、その膜のバンドギャップが、バルク物質のバンドギャップと異なる値をもつ、いわゆる量子閉じ込め効果が発生するように設定することが必要である。具体的には、量子閉じ込め効果が発生する膜厚の目安は励起子の有効ボーア半径a=(1/me+1/mh)×(εh2)/(πe2)程度とされる。ここでme、mhはそれぞれ電子および正孔の有効質量、εは誘電率、hはプランク定数、eは電気素量である。上記の式はMKSA単位系で表記されたものである。また、量子閉じ込め効果が発生する条件は、閉じ込められる膜、すなわちここではi層1、の膜厚以外にも、バリア膜44の形成するエネルギー障壁の高さおよびバリア膜44の膜厚に依存する。定量的な依存性を求めるにはシュレディンガー方程式を解く必要があるが、定性的には、バリア膜44の形成するエネルギー障壁が低くなるほど、また、バリア膜44の膜厚が減少するほど、量子閉じ込め効果は抑制され、バンドギャップはバルク物質のバンドギャップに近くなるという傾向がある。従って、所望のバンドギャップを得るためには、バリア膜44の形成するエネルギー障壁の高さおよびバリア膜44の膜厚の選択が重要である。一般に、量子閉じ込め効果によるバンドギャップのバルク物質からの変化は連続的であり、膜厚が小さくなるほど大きくなる。これを利用して、積層されるpin接合31におけるi層1の膜厚を、層ごとに異なる値とすることにより、実施例4の構造を作製することも可能である。また、本実施例5では、量子閉じ込め効果を発現する構造として、薄膜を絶縁膜で挟んだ構造、いわゆる量子井戸を例にとって説明するが、本実施例5の内容は、量子細線や量子ドットなどの、閉じ込め次元の異なる構造にも適用可能である。また、実施例3でなく、実施例1および実施例2の太陽電池セルに上記変更を適用してもよい。
図8は、本実施例6における太陽電池の構造を示す図である。この構造の特徴は、実施例1の太陽電池セルにおいて、各pin接合31のp層11およびn層21と、隣接する絶縁膜との間に、透明導電膜55を挿入するということである。この透明導電膜55としては、上記p層11およびn層21のいずれと比べてもシート抵抗が低いことが必要であり、太陽光の波長域における透過率が高いことが望ましく、これらの条件を満たすように、透明導電膜55の膜種と膜厚を選択する必要がある。また、実施例1でなく、実施例2および実施例3の太陽電池セルに上記変更を適用してもよい。
図9は、本実施例7における太陽電池の構造を示す図である。この構造は、本発明の実施例1の太陽電池セルと、従来型太陽電池セル63、すなわち、単一のpn接合あるいはpin接合のみからなるセル、とを直列接続したタンデム構造である。図9では、従来型太陽電池セル63の裏面側にp側電極が形成され、表面側にn層が形成され、そのn層と、本発明の太陽電池セルのp層側貫通電極51とが接続され、本発明の太陽電池セルのn層側貫通電極52はセル表面のn層側電極54と接続されている。これらのp層とn層とを反転した構造でもよい。また、実施例1でなく、実施例2から実施例6までのいずれの太陽電池セルを用いてもよい。従来型太陽電池63と本発明の太陽電池との接続部にトンネル接合ダイオードを形成してもよい。以下では、従来型太陽電池63の表面絶縁膜と、本発明の太陽電池の裏面絶縁膜43を同一の膜として説明するが、これらは互いに異なってもよい。
Claims (15)
- 第1のp層と、
第1のn層と、
前記第1のp層と前記第1のn層の間に設けられる第1のi層と、
第2のp層と、
第2のn層と、
前記第2のp層と前記第2のn層の間に設けられる第2のi層と、
前記第1のn層と前記第2のp層の間に設けられる第1の絶縁層と、
前記第1のp層とは異なるp層を介して前記第1のp層と接続され、前記第2のp層とは異なるp層を介して前記第2のp層と接続される第1の貫通電極と、
前記第1のn層とは異なるn層を介して前記第1のn層と接続され、前記第2のn層とは異なるn層を介して前記第2のn層と接続される第2の貫通電極と、を有し、
前記第1のi層の膜厚は、前記第1のp層の膜厚及び前記第1のn層の膜厚よりも厚く、
前記第2のi層の膜厚は、前記第2のp層の膜厚及び前記第2のn層の膜厚よりも厚いことを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1のp層とは異なるp層は、第3のp層であり、
前記第2のp層とは異なるp層は、第4のp層であり、
前記第1のn層とは異なるn層は、第3のn層であり、
前記第2のn層とは異なるn層は、第4のn層であり、
前記第3のp層と前記第4のp層の間、及び、前記第3のn層と前記第4のn層の間に、前記第1の絶縁層が設けられることを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1のp層とは異なるp層と、前記第2のp層とは異なるp層は、同一のp層であり、
前記第1のn層とは異なるn層と、前記第2のn層とは異なるn層は、同一のn層であることを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1の貫通電極と前記第2の貫通電極は、フェルミ準位が互いに異なることを特徴する太陽電池。 - 請求項1記載の太陽電池において、
前記第1のp層と前記第2のp層は、バンドギャップが互いに異なり、
前記第1のi層と前記第2のi層は、バンドギャップが互いに異なり、
前記第1のn層と前記第2のn層は、バンドギャップが互いに異なることを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1のp層と前記第1のi層の間に設けられる第2の絶縁層と、
前記第1のi層と前記第1のn層の間に設けられる第3の絶縁層と、
前記第2のp層と前記第2のi層の間に設けられる第4の絶縁層と、
前記第2のi層と前記第2のn層の間に設けられる第5の絶縁層とをさらに有することを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1の絶縁層と前記第2のp層の間に設けられる第1の導電膜をさらに有し、
前記第1の導電膜は、前記第2のp層、前記第2のi層及び前記第2のn層が吸収する波長の光に対する吸収率が、前記第2のp層、前記第2のi層、及び前記第2のn層よりも低いことを特徴とする太陽電池。 - 請求項1記載の太陽電池において、
前記第1の貫通電極又は前記第2の貫通電極と接続される太陽電池セルをさらに有し、
前記太陽電池セルは、単一のpn接合又は単一のpin接合を有することを特徴とする太陽電池。 - 第1のp層と、
第1のn層と、
前記第1のp層と前記第1のn層の間に設けられる第1のi層と、
第2のp層と、
第2のn層と、
前記第2のp層と前記第2のn層の間に設けられる第2のi層と、
前記第1のn層と前記第2のp層の間に設けられる第1の絶縁層と、
前記第1のp層、前記第1のn層、前記第1のi層、前記第2のp層、前記第2のn層、前記第2のi層、及び前記第1の絶縁層を貫通する第1の貫通電極と、
前記第1のp層、前記第1のn層、前記第1のi層、前記第2のp層、前記第2のn層、前記第2のi層、及び前記第1の絶縁層を貫通し、前記第1の貫通電極とはフェルミ準位が異なる第2の貫通電極と、を有し、
前記第1のi層の膜厚は、前記第1のp層の膜厚及び前記第1のn層の膜厚よりも厚く、
前記第2のi層の膜厚は、前記第2のp層の膜厚及び前記第2のn層の膜厚よりも厚いことを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1の貫通電極は、第3のp層を介して前記第1のp層と接続され、第4のp層を介して前記第2のp層と接続され、
前記第2の貫通電極は、第3のn層を介して前記第1のn層と接続され、第4のn層を介して前記第2のn層と接続され、
前記第3のp層と前記第4のp層の間、及び、前記第3のn層と前記第4のn層の間に、前記第1の絶縁層が設けられることを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1の貫通電極は、第3のp層を介して前記第1のp層及び前記第2のp層と接続され、
前記第2の貫通電極は、第3のn層を介して前記第1のn層及び前記第2のn層と接続されることを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1のp層と前記第2のp層は、バンドギャップが互いに異なり、
前記第1のi層と前記第2のi層は、バンドギャップが互いに異なり、
前記第1のn層と前記第2のn層は、バンドギャップが互いに異なることを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1のp層と前記第1のi層の間に設けられる第2の絶縁層と、
前記第1のi層と前記第1のn層の間に設けられる第3の絶縁層と、
前記第2のp層と前記第2のi層の間に設けられる第4の絶縁層と、
前記第2のi層と前記第2のn層の間に設けられる第5の絶縁層とをさらに有することを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1の絶縁層と前記第2のp層の間に設けられる第1の導電膜をさらに有し、
前記第1の導電膜は、前記第2のp層、前記第2のi層及び前記第2のn層が吸収する波長の光に対する吸収率が、前記第2のp層、前記第2のi層、及び前記第2のn層よりも低いことを特徴とする太陽電池。 - 請求項9記載の太陽電池において、
前記第1の貫通電極又は前記第2の貫通電極と接続される太陽電池セルをさらに有し、
前記太陽電池セルは、単一のpn接合又は単一のpin接合を有することを特徴とする太陽電池。
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