JP5640948B2 - Solar cell - Google Patents

Description

  The present invention relates to a solar cell using a photovoltaic cell having a heterojunction on the surface of a semiconductor substrate.

  In recent years, various devices used for photovoltaic power generation using photovoltaic power (individual units that generate photovoltaic power are referred to as solar cells or simply cells) have been developed. Crystalline devices using substrates and thin film devices using thin film semiconductors such as silicon are known.

  In addition, solar cells using a hybrid cell having a heterojunction between a single crystal silicon substrate and an amorphous silicon thin film have been put into practical use, and this is because a solar cell with particularly high conversion efficiency has been realized. Attention has been paid. The hybrid solar cell uses a wide band gap of an amorphous film and utilizes a passivation effect by forming an amorphous film. In a hybrid solar cell, an efficient separation and recovery of electron-hole pairs is realized by providing a heterostructure pn junction with an amorphous film on the light receiving surface side so that incident light is easily absorbed.

  In general, single crystal silicon substrates are classified into an n type in which phosphorus (P) atoms are added to silicon and a p type in which boron (B) atoms are added. When the mobility of holes and electrons is compared, the mobility of electrons having a small effective mass and a small scattering cross section is large. Therefore, it is preferable to use an n-type single crystal silicon substrate in a hybrid solar cell. Therefore, the single crystal silicon semiconductor substrate used in the present invention is described on the assumption that an n-type single crystal silicon substrate is used.

The hybrid solar cell receives light from the p-type amorphous silicon thin film on the main surface that is the main light-receiving surface of the cell, and generates power in the junction and the n-type single crystal silicon substrate. Since the electrical resistance in the surface direction of the amorphous silicon thin film is large, a transparent conductive layer is provided on the p-type amorphous silicon thin film in order to reduce loss due to conduction. The electric power generated at this time can be taken out by an electrode made of a transparent conductive layer provided on the main surface and the back surface facing the main surface. In general, as a transparent conductive layer used on the light incident surface, indium oxide (In ₂ O ₃ ) added with several percent of tin, abbreviated as ITO, or aluminum (Al), abbreviated as AZO, is added. Zinc oxide added with zinc oxide (ZnO) or gallium (Ga) abbreviated as GZO is used.

  In order to improve the photoelectric conversion efficiency of the solar battery cell, it is necessary to improve the fill factor while maintaining a high short circuit current Isc and an open circuit voltage Voc. However, in the hybrid cell described above, when an n-type single crystal silicon substrate and a p-type amorphous silicon film are bonded, a large number of interface states are generated in the bonded portion, so that carrier recombination frequently occurs and is released. The voltage Voc will decrease. Therefore, in order to suppress the carrier recombination at the above junction, a substantially intrinsic amorphous silicon film (i-type amorphous silicon) is interposed between the n-type single crystal silicon substrate and the p-type amorphous silicon film. A hybrid solar cell having a heterojunction structure in which a porous silicon film is inserted is known.

  Since the transparent conductive layer is related to the optical characteristics of the light receiving surface, it is an important factor that affects the characteristics of the device. In order to obtain high photoelectric conversion efficiency, it is desirable to use a transparent conductive layer using ITO having high conductivity. Patent Document 1 discloses a technique for improving the conversion efficiency of a photovoltaic device by setting the doping amount of a metal dopant to indium oxide constituting the layer in a specific range.

  In addition, it is known that the provision of a concavo-convex structure on the surface of the crystalline silicon substrate can improve the short-circuit current by using a light confinement effect of the concavo-convex structure to prevent reflection. In this method, unevenness called texture is formed by etching with an aqueous alkali solution, and the reflectance is effectively reduced by randomly formed pyramid-shaped unevenness.

  In order to provide actual use as a solar cell, a plurality of solar cells are electrically connected, and a transparent resin such as ethylene-vinyl acetate resin (EVA resin) is filled on a glass plate as a protective substrate, A solar cell module is produced by laminating a back surface protective film such as a polyethylene terephthalate (PET) film.

JP 2004-221368 A

  However, in a hybrid solar cell using a conventional heterojunction structure, sodium (Na) ions that have passed through a translucent resin from a glass plate disposed on a transparent conductive layer after the solar cell is modularized, etc. Of impurities gradually diffused into the solar cells, reaching not only the transparent conductive layer but also the amorphous silicon film or single crystal silicon substrate, which may deteriorate the characteristics of the solar cell after a long period of time. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a solar cell that is less affected by impurities diffusing from a glass plate via a transparent conductive layer.

The solar cell of the present invention uses a cell having an amorphous silicon film having the second conductivity type on the light incident surface side of the silicon crystal substrate having the first conductivity type via an intrinsic silicon thin film. Solar cell filled with translucent resin between glass and glass plate, cell is made of transparent conductive layer formed on amorphous silicon film, and anti-reflection formed on transparent conductive layer And a collector electrode electrically connected to the transparent conductive layer, the transparent conductive layer comprising a first conductive film mainly composed of indium oxide formed on an amorphous silicon film, and a first conductive film. And a second conductive film mainly composed of zinc oxide formed on the film. The collector electrode is disposed in the opening groove formed in the antireflection layer, and the second conductive film is formed at the bottom of the opening groove. At least a part of the film remains and is in contact with the collector electrode.

In the present invention, the configuration as described above prevents the diffusion of Na ions into the modular solar cells, has high photoelectric conversion efficiency, and is a hybrid solar system that has little secular change even after long-term use. A battery can be realized.

3 is a plan view of the solar battery cell according to Embodiment 1. FIG. 4 is a cross-sectional view showing the structure of the solar cell in the first embodiment. FIG. 3 is a cross-sectional view showing the structure of the solar battery cell of Embodiment 1. FIG. FIG. 3 is a cross-sectional view showing a structural example before the collector electrode is formed in the solar battery cell of the first embodiment. 3 is an enlarged cross-sectional view showing an example of the structure around the collector electrode of the solar battery cell of Embodiment 1. FIG. 3 is an enlarged cross-sectional view showing an example of the structure around the collector electrode of the solar battery cell of Embodiment 1. FIG. 4 is a graph showing the results of an environmental test of the solar battery cell in the first embodiment. 3 is an enlarged cross-sectional view showing an example of the structure around the collector electrode of the solar battery cell of Embodiment 1. FIG. 6 is a cross-sectional view showing a structure after formation of an antireflection layer of a solar battery cell according to Embodiment 2. FIG. 6 is an enlarged cross-sectional view showing a structure around a collecting electrode of a solar battery cell according to Embodiment 2. FIG.

Embodiment 1 FIG.
FIG. 1 is a plan view of the solar battery cell C of the present invention as viewed from the light incident surface (light receiving surface) side, and collector electrodes S arranged in parallel at substantially equal intervals, and buses connected to the collector electrodes S. It has an electrode B. The arrangement pitch of the collector electrodes S is, for example, 1 mm to 3 mm. The size of the cell is determined by the single crystal silicon substrate to be used, and for example, a rectangular shape having a side length of 125 mm or 156 mm (a square or a shape close to a square) is used.
FIG. 2 is a cross-sectional view schematically showing the structure of solar cell 100 of the first embodiment. A plurality of solar cells C connected in series are arranged between glass substrate G and protective film F, and are transparent. An operable module is configured by being sealed in the optical resin R.

  FIG. 3 is a cross-sectional view showing the structure of the solar battery cell C of the first embodiment, and schematically shows the structure cut along the a-a ′ line of FIG. 1. An i-type amorphous silicon-based thin film layer 2 and a p-type amorphous silicon-based thin film layer 3 are formed on the main surface side which is a light-receiving surface of a single crystal silicon substrate 1 having an n-type conductivity type. It has a structure and forms a portion for generating photovoltaic power. On the p-type amorphous silicon-based thin film layer 3, an optically substantially transparent first conductive film 6 mainly composed of indium oxide such as ITO, and further optically substantially transparent AZO are formed thereon. Alternatively, a second conductive film 8 made of GZO is formed. A layer in which the first conductive film 6 and the second conductive film 8 are overlapped is referred to as a “transparent conductive layer”. The conductive film 8 made of zinc oxide has a conductivity lower than that of the conductive film 6 made of ITO, but has sufficient conductivity to conduct electricity and functions as an electrode of the solar battery cell.

An antireflection layer 10 is formed on the transparent conductive layer, that is, on the conductive film 8. Since the material of the antireflection layer 10 has a dense film quality, silicon nitride (Si ₃ N ₄ to SiN _x ) which has a property of hardly transmitting moisture and other impurities and can expect a barrier effect of Na ions is preferable. . In addition, the antireflection layer 10 may be a thin film made of silicon nitride oxide (SiON) in which oxygen is contained in silicon nitride.

  A plurality of collector electrodes S1 are connected to the transparent conductive layer 6 to provide a path for passing a current generated by the photovoltaic force. In FIG. 3, a groove-shaped opening is formed in the antireflection layer 10 and the conductive film 8, and one collector electrode S1 is disposed in the groove, and the collector electrode S1 and the conductive film 6 are in contact with each other. Connected.

  Here, when EVA resin is used for the translucent resin R, the refractive index of the translucent resin R in the vicinity of the wavelength of incident light of 500 nm is about 1.5, and the refractive index of the AZO film of the conductive film 8 is 1. .8 to 2.0. The AZO film can realize a refractive index of 2.0 or less by adjusting the ratio of Al to be added, for example.

In order to reduce the reflectance of the solar battery cell C, it is desirable that the refractive index of the antireflection layer 10 takes a value between the translucent resin R and the conductive film 8. When silicon nitride is used for the antireflection layer 10, the refractive index can be adjusted to 2.0 or less by adjusting the flow rate ratio of, for example, SiH ₄ gas and NH ₃ gas during film formation by plasma CVD. In the case of silicon nitride oxide, film formation may be performed using oxygen gas in combination, and a general refractive index is about 1.6.

When ITO formed by adding about 10 wt% of tin oxide (SnO ₂ ) to the conductive film 6 is used, the refractive index is about 2.1 to 2.2. By adjusting the film forming conditions of each layer, the refractive index decreases in the order from the p-type amorphous silicon thin film layer 3 to the conductive film 6, the conductive film 8, the antireflection layer 10, and the translucent resin R. can do. By changing the refractive index stepwise, the refractive index difference at the interface of each layer can be reduced, so that the reflectance of the solar battery cell C can be reduced.

  In addition to the above example, if the material of each layer is selected so that the refractive index changes stepwise, the difference in refractive index at the boundary of each layer becomes small, so the reflectance on the main surface side of the solar cell C is reduced. In addition, the loss of solar energy due to surface reflection can be reduced. Moreover, you may use the gradient material from which a refractive index changes continuously instead of step shape.

In the case of silicon nitride, the antireflection layer 10 is generally formed by a plasma CVD method using SiH ₄ or NH ₃ gas. Therefore, the film forming member has a strong reducing action due to hydrogen plasma generated during film formation. receive. Therefore, when silicon nitride is formed with the conductive film 6 made of ITO exposed, indium in the ITO is reduced, the light transmittance is reduced, and the light absorption loss is increased. However, when the conductive film 6 is covered with the conductive film 8 made of AZO, there is an effect of suppressing ITO from being cut off from plasma and being reduced during the formation of the antireflection layer 10. That is, the conductive film 8 functions not only as an electrode but also as a reduction preventing layer of the conductive film 6. When silicon nitride oxide is used for the antireflection layer 10, the same effect can be obtained because SiH ₄ is used when forming the silicon nitride oxide film. As a result, these antireflection layers 10 contain hydrogen inside.

  Therefore, the transparent conductive layer using the ITO / AZO bilayer film realizes the solar battery cell C having high durability against the film forming process of the antireflection layer 10 and low light absorption loss. In the case of an ITO / GZO transparent conductive layer, it has an effect equivalent to this.

  As described above, by using the solar battery cell C of the first embodiment, not only the light reflection loss is small, but also the light absorption loss is small. Therefore, the hybrid solar battery 100 with high photoelectric conversion efficiency is obtained. Can be realized.

  In addition, on the back surface side (opposite to the light receiving surface) of the solar battery cell C in FIG. 3, an i-type amorphous silicon-based thin film layer 4, an n-type amorphous silicon-based thin film layer 5, and a conductive film 7 made of ITO. , AZO or GZO conductive film 9, antireflection layer 11, and collector electrode S2. With this back surface structure, holes generated by light transmitted through the single crystal silicon substrate 1 are prevented from diffusing to the conductive film 7 side, and stress is symmetrized by the front and back symmetrical structure to suppress the warpage of the solar battery cell C. Yes. In addition, when there is incident light from the back side, it has the effect of suppressing the reflection and increasing the conversion efficiency.

  In addition, the texture may be formed on both surfaces of the n-type single crystal silicon substrate 1, and in that case, the micro structure of each conductive film and the antireflection layer is formed on the texture structure arranged at random. The

  Hereinafter, the manufacturing method of the hybrid type silicon solar battery cell C of Embodiment 1 shown in FIG. 3 will be described. First, after washing the n-type single crystal silicon substrate 1 having an incident plane of (100) and a thickness of about 200 μm with an organic solvent, acid, alkali, etc., an aqueous sodium hydroxide solution heated to 70 to 90 ° C. Immersion is performed to remove the damaged layer generated during slicing, and cleaning with pure water is performed. Further, a dry cleaning method such as plasma, UV or ozone, or a cleaning method according to the substrate surface state such as heat treatment may be used.

  Next, as a method of forming a texture structure on both surfaces of the crystalline silicon substrate 1, it is immersed in an aqueous solution of potassium hydroxide (KOH) and isopropyl alcohol (IPA) maintained at 70 to 90 ° C. and rinsed with pure water. As a result, the substrate surface is etched, and a texture having an average period and height of irregularities of several μm to several tens of μm is formed. The formed texture structure is a shape in which pyramid-shaped protrusions with the (111) plane exposed are randomly arranged. The etching conditions for texture formation are adjusted so that the etching rate has a relationship of (100)> (110) and (100)> (111). An etching solution in which IPA is added to an alkaline aqueous solution has an effect of increasing the etching rate ratio between the (100) plane, the (110) plane, and the (111) plane.

  The etching solution is not limited to potassium hydroxide, and other alkaline solvents such as sodium hydroxide may be used, and additives other than IPA may be used.

  After the etching is completed, the single crystal silicon substrate 1 is introduced into a CVD apparatus, and an i-type amorphous silicon layer 2 is formed on the incident surface to a thickness of about 5 nm. The type amorphous silicon layer 3 is formed, for example, with a thickness of about 5 nm. Further, the i-type amorphous silicon layer 4 is formed on the back side by about 5 nm, and the n-type amorphous silicon layer 5 is formed on the i-type amorphous silicon layer 4 by about 15 nm. Before forming these amorphous silicon films, it is desirable to perform a process of cleaning the film forming surface by wet cleaning using acid or alkali, or dry cleaning using plasma or the like.

Subsequently, an ITO film having a thickness of 50 to 150 nm is formed as the conductive film 6 on the main surface side p-type amorphous silicon layer 3 by a sputtering method. For example, a sputtering target obtained by adding 0.5 to 5% of SnO ₂ to In ₂ O ₃ can be used.

An AZO film having a thickness of 20 to 50 nm is formed on the conductive film 6 as a conductive film 8 that protects the conductive film 6 by a sputtering method. As the sputtering target, one obtained by adding 0.5 wt% to 4 wt% of Al to ZnO can be used.
Note that the amount of ITO containing rare In can also be reduced by reducing the thickness of the ITO film and increasing the thickness of the AZO film to be equal to or higher than that of the ITO film.

  Similarly, an indium oxide layer of 50 to 100 nm is formed as a conductive film 7 on the n-type amorphous silicon layer 5 on the back surface side by a sputtering method. The sputtering method was used as the method for forming the transparent conductive layer of the present embodiment. However, the vapor deposition method, the ion plating method, the thermal CVD method, the MOCVD method, the sol-gel method, the method of spray heating the liquefied raw material, or the ink jet It can be formed using a method or the like. A conductive film 9 is formed on the conductive film 7 in the same manner as the conductive film 8.

Next, as the antireflection layer 10 on the conductive film 8, a SiN _x film or a SiON film is formed by a plasma CVD method using a high frequency discharge as a plasma source. As the source gas, a mixed gas system containing SiH ₄ gas is used. For example, SiH ₄ —N ₂ system, SiH ₄ —NH ₃ system, SiH ₄ —N ₂ —NH ₃ system can be used, and H ₂ is appropriately used. Diluted with gas. In general, the refractive index decreases as the nitrogen content in the film decreases. Therefore, the refractive index can be controlled by adjusting the amount of N ₂ gas and NH ₃ gas supplied to the SiH ₄ gas. When forming the SiON film, O ₂ gas is mixed into the above mixed gas system. The antireflection layer 10 is formed to have a film thickness of several to several tens of nm, preferably 40 to 50 nm. The film forming substrate temperature at the time of film formation may be 300 ° C. or lower, but more preferably 200 ° C. or lower. The same applies to the formation of the antireflection layer 11 on the conductive film 9.

  Next, a plurality of openings K serving as contact portions between the conductive film 6 and the collector electrode S1 are formed. (See FIG. 4.) The steps of removing the silicon nitride / zinc oxide layer in the opening K include laser processing using a XeF excimer laser (wavelength 353 nm), dry etching using a resist mask, and wet using a mixed aqueous solution of hydrochloric acid and nitric acid. Etching or the like can be used. The openings K have a width of about 50 to 300 μm and are arranged substantially in parallel at a predetermined interval. Further, when forming the antireflection layer 10, a method of preventing the opening from being formed with a mask or the like may be used. A similar opening K is also formed in the contact portion between the conductive film 7 and the collector electrode S2.

  After forming the opening K, a comb-shaped electrode was formed on the conductive films 6 and 7 by a screen printing method using a conductive paste to form collector electrodes S1 and S2. The conductive paste is a paste in which metal particles such as silver and a resin binder are kneaded and dispersed. After printing, the conductive paste is solidified by annealing at about 200 ° C. within a range where the silicon passivation does not deteriorate. The transmittance and resistivity of the conductive films 6 and 7 vary depending on the annealing temperature and atmosphere of the collector electrode. This is considered to be due to the change in film quality due to moisture, oxygen, etc. from the annealing atmosphere or paste.

FIG. 5 is an enlarged cross-sectional view showing an example of the structure around the collector electrode of the solar battery cell of the first embodiment. In this structural example, the width of the collector electrode S1 is narrower than the opening K, and the surface of the conductive film 6 is slightly exposed around the end of the collector electrode S1. Since the entire width of the collector electrode S1 is in contact with the conductive film 6, a solar cell with low electrical resistance and low conduction loss can be realized even if the collector electrode S1 designed to be thin to minimize light shielding is used. I can do it. The exposed area of the conductive film 6 is determined from the allowable diffusion amount of Na ions and the alignment accuracy of the collector electrode S1. In FIG. 5, the texture structure is not shown.
FIG. 6 is an enlarged cross-sectional view showing another structural example around the collector electrode of the solar battery cell of the first embodiment. As shown in FIG. 6, the collector electrodes S <b> 1 and S <b> 2 are formed wider than the opening K. Since the entire width of the opening K is covered with the collecting electrode S1, even if a slight shift occurs in the alignment between the collecting electrode S1 and the opening K, the area where the collecting electrode S1 is in contact with the conductive film is difficult to reduce. It is. Therefore, it is possible to obtain a solar battery cell with little variation in electrical resistance within the cell and between individuals.
The collector electrodes S1 and S2 can be produced by a known technique such as an ink jet method, a wire bonding method, a spray method, etc., in addition to a screen printing method.

  After a plurality of the produced solar cells C are connected, EVA resin is filled on a glass plate as a protective substrate, and a PET film as a back surface protective film is laminated under reduced pressure to obtain a solar cell module.

Embodiment 2. FIG.
FIG. 7 is an enlarged cross-sectional view showing the structure around the collector electrode of the solar battery cell of the second embodiment. The solar battery cell C of FIG. 7 has a part of the conductive film 8 remaining at the bottom of the opening of the antireflection layer 10, and can be manufactured by adjusting the etching time in a dry etching process, for example. . The other structure is the same as that of the first embodiment, and there is no difference in the basic configuration and function, so the description is omitted. Since the conductive film 8 has sufficient conductivity to conduct electricity, contact with the collector electrode S1 can ensure conduction to the collector electrode S1 with almost no problem. Even when the collector electrode S1 is narrower than the opening width, the conductive film 6 immediately below is protected by the remaining conductive film 8, so that high reliability can be ensured.

  7 has a configuration in which the collector electrode S1 covers the entire opening K, a configuration in which the entire width of the collector electrode S1 is in the opening K may be used. In the latter case, impurities such as Na ions diffusing from the exposed opening K can be minimized.

Embodiment 3 FIG.
FIG. 8 is a cross-sectional view showing the structure after formation of antireflection layer 12 of the solar battery cell of the third embodiment. The single crystal silicon substrate 1, the i-type amorphous silicon-based thin film layer 2, the p-type amorphous silicon-based thin film layer 3, the transparent first conductive film 6, and the transparent second conductive film 8 are the same as those in the first embodiment. It is the same. The appearance of the solar battery cell is the same as in FIG. 1, and the structure of the modularized solar battery is the same as in FIG. In the third embodiment, the base electrode T is formed on the conductive film 8, and the antireflection layer 12 is formed after the base electrode T is formed. The antireflection layer 12 is made of the same material as the antireflection layer 10 of Embodiment 1, but is also present on the base electrode T immediately after film formation.

  The base electrode T is a metal electrode formed by a screen printing method or an inkjet method using a paste or slurry containing metal fine particles as an ink. However, the ink does not contain a polymer binder, a thermosetting resin, or the like, and is obtained by dispersing ultrafine metal particles coated with an organic substance in a solvent. The diameter of the ultrafine particles is less than 100 nm, preferably around 10 nm, and the material is Ag, Au, Cu, Ni, Mn or the like. The base electrode T is completed by annealing at about 200 ° C. after the pattern formation and sintering the ultrafine metal particles. Therefore, the base electrode T contains almost no organic component after annealing, and does not deteriorate in the film formation process of the antireflection layer 12.

  FIG. 9 is an enlarged cross-sectional view showing the structure around the collector electrode of the solar battery cell of the third embodiment. From the stage of FIG. 8, the antireflection layer 12 immediately above the base electrode T is removed, and the collector electrode S1 is formed on the base electrode T. The base electrode T and the collector electrode S1 are electrically connected to form a conduction path. If the electrical resistance of the base electrode T is sufficiently low, the collecting electrode S1 may be formed on a part of the base electrode T. Removal of the antireflection layer 12 on the base electrode T is performed by laser etching on the base electrode T using, for example, an Nd: YAG laser having a wavelength of 1064 nm. As a result, the region on the base electrode T corresponds to the opening K in the first embodiment.

  Since the conductive film 6 is protected by the conductive film 8 in the solar battery cell of FIG. 9, Na ions are prevented from diffusing inside the cell after being modularized, as in the first embodiment. A hybrid solar cell with little secular change even when used for a period is realized.

  In the above description, the antireflection layers 10 and 11 have been described on the assumption that they are formed by the plasma CVD method. However, similar effects can be expected even when the antireflection layers 10 and 11 are formed by the sputtering method. That is, the conductive film 8 containing AZO or GZO as a main component prevents damage to the ITO film due to excited molecules in the plasma and ions that are accelerated and incident on the film formation substrate. It is possible to suppress diffusion of impurities such as Na ions.

  Specific examples based on the above embodiment will be described below.

Example 1.
As a solar cell using the configuration of the above embodiment, a cell having the structure of FIG. 5 around the collector electrode S1 was produced. The width of the collecting electrode S1 was narrower than the opening K, the width of the opening K was 150 ± 5 μm, and the width of the collecting electrode S1 was 100 ± 10 μm. The ITO film thickness of the conductive film 6 was 50 nm, the AZO film of the conductive film 8 was 30 nm, and the total film thickness was 80 nm, both of which were formed by sputtering. As the antireflection layer 10, a silicon nitride film having a film thickness of 40 nm was formed by plasma CVD. The pitch of the collector electrodes S1 was 2 mm. The structure around the collector electrode S2 on the back surface was also the same.
The evaluation module was filled with EVA resin on a glass plate, and a PET film was laminated on the back surface with a laminator and sealed.

Example 2
Further, a cell having a structure in which the widths of the collector electrodes S1 and S2 shown in FIG. Specifically, the width of the opening K is the same as in Example 1, and the widths of the collector electrodes S1 and S2 are 200 ± 10 μm. Other than that was carried out similarly to Example 1, and produced the solar cell module. Since the collector electrodes S1 and S2 are wide, the entire width of the opening K is covered with the collector electrodes S1 and S2.

Comparative example.
The same as in Example 1 except that the antireflection layer and the zinc oxide layer are not formed in the cell, and a plurality of openings K serving as contact portions between the conductive film 6, the collector electrode S1, and the conductive film 7, and the collector electrode S2 are not formed. Thus, a solar cell module was produced.

  When the initial output characteristics of the solar cell module of the above example were measured by a solar simulator, the short circuit current increased by 2% in Example 1 and 1% in Example 2 compared to the solar cell module of the comparative example. Increased. From this result, it can be inferred that the light utilization efficiency has increased due to the effect of the antireflection layer 10 of Example 1. Moreover, since Example 2 has a wide collector electrode S1, it can be inferred that the effect of lowering the light utilization rate compared to Example 1 appeared. Furthermore, in the comparative example, in the annealing process for solidifying the conductive paste used for the collector electrode S1, the conductive film 6 is exposed to oxygen or water vapor in a high-temperature atmosphere, so the conductivity of the conductive film 6 decreases. It is thought that the effect is superimposed.

  Next, the reliability of the solar cell module was evaluated by a temperature and humidity environment test. The sample used for the reliability evaluation was subjected to a temperature and humidity cycle test using a simple structure in which the cell was sealed with EVA resin on soda lime glass. The conditions of the moisture resistance test are in accordance with JIS C8917. The temperature and humidity are set to 85 ° C and 85%. Store the sample in the bag for a certain period of time and measure the output of each sample. The test was repeated.

  FIG. 10 is a graph showing the results of an environmental test for 1,000 hours on the above-described solar battery cell. From FIG. 10, it was found that the solar cell modules of Examples 1 and 2 had less change in the curve factor and improved reliability in the temperature and humidity resistance environment as compared with the solar cell module of the comparative example. From this result, it is surmised that the solar cell C of the first embodiment is less likely to be deteriorated in characteristics due to the entry of impurities such as Na ions contained in the glass plate G into the cell, and the structure of the second embodiment is the most reliable. It is thought that it is excellent in property.

  Thus, it was found that the structures of Examples 1 and 2 are effective for improving the conversion efficiency and improving the reliability due to an increase in the short-circuit current. Therefore, the solar battery cell C according to the first embodiment prevents Na ions from diffusing inside the modularized cell, prevents cell characteristic deterioration, and has high photoelectric conversion efficiency. Thus, the hybrid solar cell 100 having a small secular change even when used for a period is realized.

1 n-type single crystal silicon substrate 2, 4 i-type amorphous silicon film 3 p-type amorphous silicon film 5 n-type amorphous silicon film 6, 7 first transparent conductive film 8, 9 second transparent conductive film 10 , 11 Antireflection layer S, S1, S2 Collector electrode B Bus electrode C Solar cell T Base electrode

Claims (3)

A cell having an amorphous silicon film having a second conductivity type on a light incident surface side of a silicon crystal substrate having a first conductivity type with an intrinsic silicon thin film interposed between the cell and the glass plate is used. A solar cell filled with a translucent resin,
The cell is
A transparent conductive layer formed on the amorphous silicon film;
An antireflection layer formed on the transparent conductive layer;
A collector electrode electrically connected to the transparent conductive layer,
The transparent conductive layer includes a first conductive film mainly composed of indium oxide formed on the amorphous silicon film, and a second conductive film mainly composed of zinc oxide formed on the first conductive film. Comprising a conductive film,
The collector electrode is disposed in an opening groove formed in the antireflection layer,
The solar cell according to claim 1, wherein at least a part of the second conductive film remains in contact with the collector electrode at the bottom of the opening groove . The solar cell according to claim 1 , wherein the collector electrode is connected to the second conductive film via a base electrode. The solar cell according to claim 1 , wherein the antireflection layer is formed by a plasma CVD method.

Images