MXPA97003578A - Process for the production of a photovolta element - Google Patents

Abstract

A process for producing a photovoltaic element, the process comprising the steps of: providing a photovoltaic element comprising a lower electrode layer containing a metal layer comprising aluminum or an aluminum compound and a transparent and electrically conductive layer, a semiconductor layer photoelectric conversion and a transparent electrode layer stacked in the order mentioned on an electrically conductive surface of a substrate and immerse the photovoltaic element, in an electrolytic solution to passively make a current path in short circuit that has defects in the photovoltaic element, by the action of an electric field, where the electrolyte solution, has a chlorine ion content of 0.03 mol / 1 or men

Description

PAR PROCESS? L? PRODUCTION OF A PHOTOVOLTAIC ELEMENT BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a process for producing a highly reliable photovoltaic element. More particularly, the present invention relates to a process for producing a highly reliable f? Tolvolt? Ico element with superior characteristics by subjecting a photovoltaic element having a defect in the path of the short-circuited current in it, to the electrolytic treatment using a solution of electrolytes specified to passivate or neutralize the fault of the path of the short-circuited current present in the photovoltaic element.

Technical background in recent years studies have been carried out to develop a photovoltaic element with a large area that can be used, for example, as a solar cell for power generation. In particular, various studies have been carried out to develop a large area photovoltaic element that fears a multiple layer structure consisting of a semiconductor material composed of an amorphous material such as an amorphous silicon (a-Si) material. To produce this large-area photovoltaic element, public attention has focused on a continuous process to form a film such as the so-called roll-to-roll process to form the film. However, it is difficult to efficiently and stably produce a large-area photovoltaic element with a multi-layered structure which is free of defects, such as short circuit defects in the entire area thereof. For example, in the case of a thin-film, large-area photovoltaic element having a stacked semiconductor structure consisting of a plurality of semiconductor films formed of an amorphous material such as a-Si stacked, it is known that during formation of the stacked semiconductor structure, it is possible that defects such as perforations due to contamination by foreign matter such as dust or the like appear in the formed film, and these defects lead to derivations or short circuit defects that result in the elaboration of an element photovoltaic with markedly lower characteristics than those necessary for a photovoltaic element, particularly in the voltage generation characteristic (in terms of the voltage component). In the present we will describe the reasons why these defects occur. For example, in the case of an amorphous silicon photovoltaic element (or an amorphous silicon solar cell) formed on a surface of a metal substrate, as a stainless steel substrate, the substrate surface is not a completely smooth surface but rather it generally presents irregularities based on a fissure, cavity or protrusion with a barb shape and often an electrode layer (or a retroreflective layer) is formed on the surface of the substrate having an uneven surface provided with irregularities to scatter the light. And, on this uneven substrate surface or this irregular surface of the electrode layer, a n-type po semiconductor layer consisting of a thin semiconductor film having a thickness of several hundred angstroms is formed, which is difficult completely cover the irregularities present on the surface of the substrate or on the surface of the electrode layer and due to this, defects such as perations in the photovoltaic element of amorphous silicon are liable to occur. In this case, it is possible that perforations also appear due to fine powders during the process of ion formation of the film. In the case of an amorphous silicon fctovolta co element (or an amorphous silicon solar cell) consisting of a lower electrode layer, a semiconductor photoelectric conversion layer consisting of a plurality of amorphous silicon thin films stacked and having perforations as described in the above, and a transparent top layer stacked in the aforementioned order on a substrate having a surface provided with a defect such as barbed protrusions as described above, the photovoltaic element is problematic because the semiconductor photoelectric conversion layer results defective, due to the perforations, to make the contact directly from the lower electrode layer with the upper transparent electrode layer or to make contact with the defect of the substrate surface. There is also a problem when the semiconductor photoelectric conversion layer is not completely faulty but is in a state with a bypass or shorted portion having a low electrical resistance. In this case, an electric current generated by the semiconductor photoelectric conversion layer during the irradiation of light thereto sometimes flows in parallel to the transparent upper electrode layer to flow towards an electrically low portion of the derived or short-circuited portion, where there is a loss in the electric current. When this loss of electrical current must occur, the open-circuit voltage, that is, the voltage-generating characteristic of the photovoltaic element (the solar cell), decreases markedly. This phenomenon is more significant ba]? conditions of a low illumination intensity. This situation is seriously problematic for a solar cell for which effective energy generation is required under all climatic environmental conditions. For the photovoltaic element (or solar cell) having this portion short-circuited as described above in which an electric current flows to make the aforementioned loss in the electric current, there is a demand to decrease the loss in the electric current as much as possible. In order to meet this demand, a way of decreasing the loss in the electric current has been proposed by directly eliminating the aforementioned defects such as perforations or electrically isolating or removing the peripheral material from the short-circuited portion. Particularly, U.S. Patent No. 4,729,970 (hereinafter referred to as "document 1") discloses a way of contacting a conversion reagent with a portion with a short circuit defect present in a leaflet device having a transparent and electrically conductive film to make it a portion of the transparent and electrically conductive film in the vicinity of the short-circuit defect portion has a high electrical resistance, whereby the short-circuit defect portion of the electrode of the photovoltaic device is electrically isolated. U.S. Patent No. 5,084,400 (hereinafter referred to as document 2) discloses a form of immersion of the photovoltaic device, with an electrically conductive layer which is formed on a metal substrate having a portion with a short circuit defect in it, in a solution of an inorganic acid such as HSO * or the like while applying an electrical voltage to it to cause a portion of the electrically conductive film in the vicinity of the defective and short circuit portion to have a high electrical resistance, for means of which the portion with short circuit defect of the electrode of the photovoltaic device is electrically isolated. U.S. Patent No. 5,320,723 (hereinafter referred to as document 3) discloses a way to remove a portion with coro-circuit defect present in a photoelectric conversion device by means of electrolytic treatment using an electrolyte solution containing an inorganic or organic acid , an inorganic or organic base, or a metallic salt. In addition to these, it is known that to improve the efficiency of the use of light in a photovoltaic element containing a semiconductor layer of photoelectric conversion formed on a substrate, the light reaching the substrate through the photoelectric conversion semiconductor layer is reflected by means of a metallic layer as a retroreflective layer formed between the substrate and the photoelectric conversion semiconductor layer to return it to the semiconductor photoelectric conversion layer. It is known that the metal layer is constituted by a metal material having a higher reflectance than Ag. However, for the Ag used in this case, it is known that the Ag easily reacts with moisture to make a dendritic crystal growth of Ag which carries with it a derivation in the 1 erpento l ot.ovol t / nco. In this sense, the metallic layer as the restroreflective layer is usually constituted by an aluminum material. It is also known that to prolong the length of the optical path of the light in the semiconductor photoelectric conversion layer by means of light reflection, a transparent and electrically conductive layer consisting of ZnO or the like and having an irregular surface is arranged between the retroreflective layer and the semiconductor photoelectric conversion layer. However, in the case of eliminating a defect such as in the short-circuit defect portion present in a photovoltaic element consisting of a multilayer photoelectric conversion semiconductor layer and having a retroreflective layer composed of the aluminum material and / or the transparent and electrically conductive layer by means of any of the ways of removing defects described in the foregoing, these problems can occur as will be described. In the case of the form described in document 1, when a conversion reagent is used which contains a salt of a l.ewis acid and an anti-ruthenic element, particularly, a solution containing a chloride salt as being ALCi3, ZnCl2 or similar, or amphoteric metal such as Al is liable to significantly corrode the retroreflective Al layer, causing a problem that collateral effects occur such as flaking of the film, for example, at the interface between the Al layer and the ZnO layer. In the case of the form described in document 2, there is a problem in that, when the electrolyte solution is used for a prolonged period of time, the acidic component thereof is concentrated so that control is difficult to carry out the stable reaction. There is also a problem in that when the acid concentration of the electrolyte solution is controlled to effectively carry out the removal of the short circuit defect portion present in a photovoltaic element having an ether layer with multiple layers consisting of, For example, a metallic layer and a transparent and electrically conductive layer containing ZnO or the like, the transparent and electrically conductive layer is exposed to corrosion. In the same way, in the case of the form described in document 3, there is a problem in that when the electrolytic solution contains chlorine ions, the side effects, such as detachment of the layer, for example, at the interface between the Al layer and the ZnO layer are likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the aforementioned problems in the prior art and to provide an improved process that allows to noticeably reduce the presence of a leakage current or losses due to defects, such as perforations, present in a large area photovoltaic element, by means of which it is possible to convert the photovoltaic element into a highly reliable photovoltaic element in which the characteristic of voltage generation at a low illumination intensity is desirably recovered. Another objective of the present invention is to provide a process for efficiently producing a highly reliable photovoltaic element and having productivity.

Another objective of the present invention is to provide a process for producing a highly reliable photovoltaic element, superior in the characteristics necessary for a photovoltaic element, by subjecting a photovoltaic element having a short-circuited current path defect in it, to the electrolytic treatment using a solution Electrolytic specifies to passivate or neutralize the defect of the short-circuited current path present in the photovoltaic element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a schematic cross-sectional view illustrating a photo-voltaic element of the present invention. Figure 1 (b) is a schematic cross-sectional plan view illustrating the side on which the light of the photovoltaic element which is shown in Figure 1 (a). Figure 2 (a) is a schematic diagram illustrating an example of an electrolytic treatment apparatus used in the present invention. Figure 2 (b) is a schematic diagram illustrating another example of an electrolytic treatment apparatus used in the present invention. Figure 2 (a) is a graph showing the interrelationships between the voltage generation characteristic and the illumination intensity for each photovoltaic element obtained in Example 1 and Comparative Example 1 which will be better described below.

DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS The present invention will be detailed in relation to the modalities that will be described below. It should be understood that the present invention is limited to these modalities. As already described, the present invention provides an improved process for efficiently producing a highly reliable photovoltaic element having productivity. A common mode of the process for the production of a highly reliable photovoltaic element consists of the steps of: providing a photographic element consisting of (a) an inner, two-layer electronic layer consisting of (ai) a metal layer composed of aluminum or an aluminum compound and (a-ii) a transparent and electrically conductive layer, (b) a semiconductor photoelectric conversion layer, and (c) a transparent electrode layer stacked in the aforementioned order on an electrically conductive substrate, and immersion of the photovoltaic element in an electrolytic solution to neutralize (or electrically isolate) a short-circuited current path defect present in the photovoltaic element by the action of an electric field, where the electrolytic solution has a chlorine ion content of U.03 mol / 1 or less. The electrolytic solution that is used in the present invention can also contain a protective ion capable of preventing the appearance of detachment of the layer at the interface between the metallic layer (a-1) with the substrate and / or at the interface between the layer metal (ai) and the transparent and electrically conductive layer ta-ii). The protective ion is an ion based on a compound that is selected from the group consisting of sufalt, nitrate, chromate, acetate, benzoate and oxalate. The electric field that is used in the present invention can be an electric field generated by the application of a polarization energy in the photovoltaic element or an electric field generated by an electromotive force of the photovoltaic element which is generated by the irradiation of light in the photovoltaic element. the photovoltaic element.

The present invention has been carried out based on the following findings obtained through experimental studies by the present inventors to achieve the objectives of the present invention. In order to neutralize a short-circuited current path defect present in a photovoltaic element consisting of a lower electrode layer, a semiconductor photoelectric conversion layer having a multilayer structure and a transparent electrode layer stacked in the order mentioned above. an electrically conductive substrate, by means of an electrolytic treatment, the present inventors carried out a form of immersion of the photovoltaic element in a specific electrolytic solution having a chlorine ion content of 0.03 mol / l or less while supplying a field electrical in the photovoltaic element, thus avoiding the loss of the lower electrode layer, by means of which the transparent electrode layer is reduced. As a result, the following data was obtained. Even in the case where the lower electrode layer is composed of an amphoteric metal material such as aluminum (Al) or an aluminum compound and a transparent and electrically conductive layer, it is interposed between the lec rico layer inferred! and the photoelectric conversion semiconductor layer or portion of the transparent electrode layer in the vicinity of a defect or perforation, in the semiconductor photoelectric conversion layer is reduced to a localized portion having an increased electrical resistance without causing the detachment of the backup layer and without causing the leakage current, wherein the initial photovoltaic element becomes a highly reliable photovoltaic element that is satisfactory in the characteristics necessary for a photovoltaic element, particularly, in the voltage generating characteristic with low illumination. The present inventors achieved other findings as will be described in the following. As the electrolytic solution, when a suitable electrolytic solution consisting of a selected electrolyte and having a chlorine content of 0.03 mol / l or less and which is capable of supplying a positive ion, is used depending on the kind of constituent of the lower electrode layer, the reduction of the transparent electrode layer placed on the semiconductor photoelectric conversion layer can be desirably achieved while avoiding the detachment of the backing layer and without the deterioration of the photovoltaic element in its external appearance and characteristics, by means of which can effectively obtain a highly reliable photovoltaic element superior in its voltage generating characteristics. In the present invention, in the case of neutralizing a short-circuited current path defect present in a element fctcvclta__v, or of rr.ut.p_.es thin layer layers consisting of a lower electrode layer, a sub-conducting layer a of con dsion t ot oe 1 «» .'t. R and a transparent electrode layer stacked in the above order on an electrically conductive substrate, by immersing the photovoltaic element in the afentioned specific electrolytic solution while supplying an electric field to the photovoltaic element, reducing the transparent electronic layer it is completed befthe backing (ie, the lower electrode layer) begins to come off, by this, side effects such as detachment of the layer can desirably be avoided in the electrolytic treatment and the voltage generation characteristic can be desirably recovered. from the photovoltaic element to a low illumination intensity. Like the electric field, when an electric field generated by applying a polarization energy to the photovoltaic element is used, there is an advantage in that the conditions related to this electric field can optionally be selected. When an electric field generated by irradiation of light in the photovoltaic element is used, the advantages exist since the electric field is not supplied excessively to the photovoltaic element, and the action of the electric field is carried out safely in the defect part, where the characteristics of the photovoltaic element are effectively recovered. Furthermore, since the substrate is electrically conductive, the wiring of the electrode works in the electrolytic treatment can be easily performed and the electrolytic treatment can be carried out efficiently. In the present invention, when polarization energy is used to generate the electric field, it is desirable that it be applied in the direction of advance towards the photovoltaic element. In this case, there is an advantage in that the electrolytic treatment for the defect portion of the photovoltaic element can be performed efficiently without the normal area of the photovoltaic element suffering any negative influence due to the application of polarization energy. In the present invention, when the transparent electrode layer consists of a metal oxide, there is an advantage in that the reduction reaction in the electrolytic treatment preferably proceeds to the transparent electric layer and not to the semiconductor photoelectric conversion layer. When in the present invention the semiconductor photoelectric conversion layer consists of an amorphous semiconductor material, a large area photovoltaic element of the present invention can be produced on a large scale by means of a roll-to-roll system.

In the following, the present invention will be detailed in relation to the drawings. Figure 1 (a) is a schematic cross-sectional view of an example of a photovoltaic device of the present invention. Figure 1 (b) is a schematic plan view taken from the incident light side of the photovoltaic element shown in Figure 1 (a). Particularly, the photovoltaic element shown in Figures 1 (a) and 1 (b) is a photovoltaic element of the amorphous silicon (a-Si) series (or a solar cell of the a-Si series) as an example of the photovoltaic element that can be used for the production of a highly reliable photovoltaic element in the present invention. It should be understood that the present invention is not limited thereto and the present invention can be applied in the production of any other lotovoltaic element. In Figures 1 (a) and 1 (b), the reference number 100 indicates a photo-voltaic element having a semiconductor photoelectric conversion layer with a multilayer structure consisting of three semiconductor photoelectric conversion layers (or three cells) , namely a first photoelectric conversion semiconductor layer 103 (hereinafter referred to as a lower cell), a second semiconductor photoelectric conversion layer 113 (hereinafter referred to as an intermediate cell) and a third semiconductor photoelectric conversion layer 123 (hereinafter mentioned as upper cell), each with a spigot connection capable of reacting with the absorption of the incident light to generate an electric current, wherein the three cells are stacked on a substrate 101. Each of the three cells 103, 113, and 123 consist of a semiconductor layer of type n, a semiconductor layer of type i and a semiconductor layer of type p that e are stacked in the order mentioned from the side of the substrate. Reference numeral 102 indicates a lower electrode (consisting of a metallic layer 102a and a transparent electrically conductive layer 102b) disposed between the substrate 101 and the semiconductor photoelectric conversion layer (consisting of the three cells 103, 113, and 123). The reference numeral 104 indicates a transparent electrode layer consisting of a transparent and electrically conductive film which is stacked on the upper cell 123. The reference number 105 indicates a grid electrode (or a collecting electrode) which is disposed on the transparent electrode layer 104. Reference number .106 indicates one the defects, such as perforations, present in the photovoltaic element.

The reference numeral 107 indicates a portion of the transparent electrode 1U4 which binds the nail with an increased electrical resistance for the electrolytic treatment of the present invention. As described in the foregoing, Figure 1 (b) is a schematic plan view taken from the incident side of the light of the photovoltaic element shown in Figure 1 (a). As is evident from Fig. 1 (b), the grid electrode 105 contains a plurality of metal wires that are arranged in a spaced manner in a desired range on the surface of the transparent electrode layer 104. Reference 108 indicates a busbar disposed in each of the opposite terminal portions of the photovoltaic element while electrically connected to the end portions of the metal wires as the grid electrode 105. Reference numeral 109 indicates a power output terminal on the pos- tive side electrically connected to The ion collector bar, ye? mipicic de roie.enci 1) 0 a power output terminal on the negative side electrically connected to the substrate 101. Here, the grid electrode 105 serves to collect an electric current generated by the semiconductor photoelectric conversion layer. The electric current collected by means of the grid electrode 105 is also collected in the bus 100, being subsequently sent to the outside by the energy output terminal on the positive side 109. The lower electrode layer 102 also serves to collect an electric current generated by the photoelectric conversion layer. The electric current collected by the lower electrode layer exits outwards through the energy output terminal on the negative side 110. The description of each constituent of the photovoltaic element 100 will be made.

Substrate In the case of a thin film multilayer photovoltaic element (or solar cell) having a photoelectric conversion semiconductor layer, with a multilayer structure, consisting of a plurality of thin semiconductor films which are stacked and which have a semiconductor junction such as a thin film photovoltaic element of the amorphous silicon (or solar cell) series, the multilayer structure is formed on a suitable substrate. In this case, the substrate serves to support the multilayer structure. The substrate in this case can be designed to also serve as an electrode (inner electrode).

Specifically, the substrate 101 in the photovoltaic element 100 shown in FIGS. 1 (a) and 1 (b) serves to support the aforementioned semiconductor photoelectric conversion layer consisting of three cells 103, 113, and 123. The substrate 101 can be an electrically conductive element constituted by an electrically conductive metallic material. The specific example of this electrically conductive element! are the metal plates such as a stainless steel plate, metal sheets such as tin foil, and the like. Alternatively, the substrate 101 may be an electrically insulating element constituted by an electrically insulating material to which an electrically conductive material is applied on at least a portion of a surface thereof. The specific example of this electrically insulating material is glass, ceramics and synthetic resins such as polystyrene and the like.

Lower Electrode The Lower electrode layer 102 (or lower electrode) is located between the substrate 101 and the semiconductor photoelectric conversion layer (which consists of three cells 103, 113 and 123). As already described, the lower electrode layer 102 consists of a metal layer 102a and the transparent electrically conductive layer 102b. The metallic layer 102a serves as an electrode for sending an electric current generated by the semiconductor photoelectric conversion layer and also serves to reflect the incident light to the semiconductor photoelectric conversion layer by means of which it facilitates the efficient utilization of the light. The metallic layer 102a may be designed with a textured surface capable of causing light to be scattered towards the semiconductor photoelectric conversion layer. It is desired that the metallic layer 102a be constituted by a suitable metallic material capable of effectively reflecting light without causing a loss in the amount of light to be reflected and without causing migration. The specific example of this metallic material is Al and an aluminum compound such as Al and the like. The metallic layer 102 can be formed by means of electroplating, vacuum deposition, cathodic sublimation or the like. The transparent and electrically conductive layer 102b serves to prevent the constituents of the metal layer 102a from diffusing into the first semiconductor photoelectric conversion layer 01 (the inner cell). The transparent and electrically conductive layer 102b may be designed with an irregular surface so that it can refract the incident light to prolong the optical path in the semiconductor photoelectric conversion layer. It is desirable that the transparent and electrically conductive layer 102b be constituted by a suitable transparent and electrically conductive material such as ZnO, ln? 0, ITO or the like. The transparent and electrically conductive layer 102b can be formed by means of electroplating, vacuum deposition, cathodic sublimation or the like.

Photoelectric conversion layer As already described, the photoelectric conversion layer in a photovoltaic element 100 has a multilayer structure consisting of three semiconductor photoelectric conversion layers (or three cells), the first semiconductor photoelectric conversion layer 103 (the lower cell), the second semiconductor photoelectric conversion layer 1.13 (intermediate cell), and the third semiconductor photoelectric conversion layer 123 (the upper cell), each with a spigot connection able to react with the absorption of light incident to generate an electric current, where the three cells 103, 113, and 123 are stacked in this order from the side of the substrate 101.

Each of the three cells 103, 113, and 123 consists of a n-type semiconductor layer, a semiconductor layer of type i, a semiconductor layer of type p which are stacked in the order mentioned above from the side of the substrate. Each semiconductor photoelectric conversion layer has a spigot connection which is constituted by a suitable semiconductor material. It can be illustrated as a semiconductor material, for example, semiconductor materials that consist of an element belonging to Group IV of the Periodic Tabia such as the semiconductor material of amorphous silicon (a-Si), polycrystalline silicon semiconductor material ( poly-Si) and microcrystalline silicon semiconductor material (μc-Si); the semiconductor conductive materials comprising the elements belonging to groups II and VI of the Periodic Table; and the semiconductor materials comprising the elements belonging to groups III and V of the Periodic Table. In the case where the photovoltaic element 100 (the solar cell) is ui. lemento .otovo.láii. the rl solai) of the amorphous silicon series, the semiconductor layer of type i in each cell can be constituted, for example, by an amorphous semiconductor material qua t * _. nga one or more elements belonging to group IV of a Table Periodic This amorphous semiconductor material, for example, amorphous silicon semiconductor material (a-Si), amorphous silicon germanium-semiconductor material (a-SiGe), and amorphous silicon carbide (a-SiC) semiconductor material. For each n-type semiconductor layer and each p-type semiconductor layer in each cell, these may be constituted, for example, by an amorphous semiconductor material containing one or more elements belonging to group IV of the periodic table that is doped with an element that controls the valence electron (a pollutant) of type not of type p. This amorphous semiconductor material can include, for example, those amorphous semiconductor materials mentioned in the foregoing which are contaminated with a valence electron (doping) controller element of type n or type P- The p-type semiconductor layer can be formed by impurifying a layer containing an amorphous semiconductor material determined with a p-type dopants using a compound that contains an element belonging to group I11A of the Periodic Table, such as B , Al, Ga, or in during the formation of the layer. The n-type semiconductor layer can be formed by impurifying a layer containing an amorphous semiconductor material determined with an n-type impurifier using a compound containing an element belonging to the VA group of the Periodic Table such as P, N, Ace , or Sb during the formation of the layer. The semiconductor layer of type p- or n- located on the incident side of the light may be constituted by a microcrystalline silicon semiconductor material (μc-Si). The semiconductor photoelectric conversion layer of the photovoltaic element 100 is of the triple cell type as already described. This fact is not limiting. The electric lotoel conversion semiconductor layer may be of a single cell type or a series type depending on the situation. The photoelectric conversion semiconductor layer having a multilayer structure, as described above, can be formed by means of a conventional film forming process such as vacuum evaporation, cathodic sublimation, CVD of RF plasma , CVD of microwave plasma, ECK, CVD induced or LP-CVD. Furthermore, to form a large-area photovoltaic element it is possible to employ a conventional roll-to-roll film forming process wherein the formation of the film is carried out while continuously moving a coil of substrate on which a film is to be formed. .

Transparent Electrode Transparent electrode 104 (or transparent electrode layer) serves to take an electromotive force generated by the photoelectric conversion layer (consisting of three cells 103, 113, and 123). The transparent electrode 104 (or transparent electrode layer) is coupled to the lower electrode 102 (or the lower electrode layer). It is necessary to use the transparent electrode 104 in the case of using a photoelectric conversion semiconductor layer having a high sheet strength as in the case of the photovoltaic element of the amorphous silicon (or solar cell) series. The transparent electrode 104 is placed on the incident side of the light of the photovoltaic element and, therefore, it is necessary that it transmits the light in a sufficient quantity. The transparent electrode is sometimes identified with the term "superior electrode". It is desired that the transparent electrode 104 have a light transmission factor of 85 ^. or more so that the transparent electrode efficiently transmits the light to the photoelectric conversion layer. In addition, it is desired that the electrode be strong. -i i < ', .ju _, o' is, if the one of or less than 100 O / I so that an electric current generated in the incident light flows in the transverse direction of the photoelectric conversion layer. The transparent electrode 104 may be constituted by a suitable transparent and electrically conductive material that can meet the aforementioned conditions. This material may include, for example, metal oxide materials such as SnO ?, In203, ZnO, CdSn04 and Li'O. The transparent electrode 104 may be formed by means of electroplating, vacuum deposition, cathodic sublimation or the like.

Grid Electrode Grid electrode 105 (the collector electrode) serves to collect the electrical current that is generated in the photoelectric conversion layer (which consists of three cells 103, 113 and 123) and which picks up the transparent electrode. The grid electrode 105 consists of a plurality of electrically conductive wires spaced apart in a desired range in a comb-like pattern on the surface of the transparent electrode 104. The width and range of the grid electrode distribution should be properly determined depending on the strength of the sheet of the transparent electrode 104. In any case, it is required that the grid electrode 105 be designed so that it has a low resistivity and does not provide a series resistance in the photovoltaic element. The grid electrode 10b may be constituted by a suitable electrically conductive material such as Ag, Ni, Al, Ti, Cr, W, or Cu. The grid electrode 105 can be formed by means of screen printing, evaporation, welding, electroplating or the like. When the latter is formed by screen printing, a way of providing an electrically conductive paste can be employed by mixing a powdery material of any of the metals, a binder resin and a solvent and screen printing the electrically conductive paste. Alternatively, the grid electrode 105 may be formed by separately distributing a plurality of metal wires constituted by any of the aforementioned metals in a desired range as shown in Fig. 1 (b). In the following, description will be made of the defects 106 (such as perforations) present in the photovoltaic element. As previously described, the total thickness of the photoelectric conversion layer (consisting of a stacked thin film semiconductor layer) formed during the production of a photovoltaic element of the amorphous silicon (solar cell) series is relatively thin. In this sense, in the case where irregularities occur on the surface of an element on which a thin semiconductor film is formed as the semiconductor photoelectric conversion layer, it is difficult to form the semiconductor film in such a way that they can be sufficiently covered. . s i i regulations. For example, in the case of forming the semiconductive film on a surface of a stainless steel plate as a substrate 101, even if the surface of the stainless steel plate is manufactured as a polished surface, it is extremely difficult for the polished surface to be absolutely free of surface defects such as protrusions, cavities or deformations. Furthermore, in the case of continuously forming a semiconductor film such as the photoelectric conversion semiconductor layer on a long substrate coil as the substrate 101 while moving the substrate coil, the substrate coil is exposed to mechanical damage such as cracks, cavities, or protrusions during transport thereof, wherein the damage sometimes comprises irregularities that are relatively large in size. When damage like this occurs, this results in a defect in the formed semiconductor film. For example, when a protrusion having a relatively large elevation is presented on the surface of the substrate on which the semiconductor film is to be formed, the semiconductive film is exposed to form in this a state of absolute non-coverage of the protrusion. When the transparent electrode is formed on the semiconductive film in this state, the protrusion of the substrate sometimes results in direct contact of the transparent electrode, where a derivation or short circuit between the substrate and the transparent electrode is originated through the semiconductor film. Furthermore, when the foreign matter such as the powder is deposited during the formation of the semiconductor film as the semiconductor photoelectric conversion layer, the foreign matter contaminating the semiconductor film gives rise to a region without film, a portion with detachment of the layer or a perforation in the semiconductor film. In this case, it is possible that a problem is caused since the transparent electrode is formed on this semiconductor film in an extension state to make contact with the inner electrode layer or the substrate, where a derivation or short circuit occurs. The presence of this defect includes particularly in the voltage generating characteristics the photovoltaic element at a low illumination intensity. Specifically, the voltage generation characteristic of the photovoltaic element increases linearly when the intensity of the illumination increases, where the voltage component will increase exponentially. Particularly in this regard, for the voltage component, when the illumination intensity is sufficiently large, for example, in the extreme case of 1.5 AM, there is no substantial difference depending on the magnitude of the defect. However, when the illumination intensity decreases, a distinguishable difference will increase between the case with zero defects and the case with defects. This trend becomes significant when the illumination intensity becomes less than 1000 Lux. With this consequence it is important that the photovoltaic element is free of this influence due to the defect for use in an environment where there is not enough or sunlight does not exist. Next, the description of the electrolytic treatment of the present invention will be made. In the present invention, during the preparation of portions 107 of the transparent electrode layer 104 which is located on the defects 10b present in the photoelectric conversion semiconductor layer (which consists of lsti is cel as 10 i, I iiy .i) In order to have an increased electrical resistance through the electrolytic treatment of the present invention, defects in the electric current path based on the defects 106 can desirably be prevented. The formation of any of the portions 107 having an electrical resistance Increased (this portion hereinafter will be referred to as a portion having a high electrical resistance) is carried out only in the vicinity of the defect. Therefore, the electrical resistance of the transparent electrode layer 104 does not increase substantially and the strength of the series of the entire photovoltaic element is not increased. The electrolytic treatment of the present invention can be carried out using an apparatus suitable for the electrolytic treatment. Figure 2 (a) is a schematic diagram illustrating an example of this apparatus for electrolytic treatment, in which an external energy source is used. Figure 2 (b) or, a diagrammatic diagram showing another example of this apparatus for the electrolytic treatment, in which a light irradiation medium is used. In Figures 2 (a) and 2 (b), the reference number 200 indicates a photovoltaic element consisting of a lower electrode layer 202, a photoelectric conversion semiconductor layer formed with multiple layers 203 having a p-type semiconductor layer. as the outermost constituent layer, and ur transparent electrode layer 204 stacked in the aforementioned order on an electrically conductive substrate 201, wherein the semiconductor layer 203 has defective portions 205. Reference number 206 indicates a container for electrolytic treatment that contains an electrolytic solution 207 in it. The reference numeral 208 indicates a counter-electrode provided in the container for the electrolytic treatment 206 during immersion in the electrolytic solution 207 (see Figure 2 (a)). Reference number 209 indicates a source of energy, and e! relerance number 210 a medium for light irradiation. Of the present invention, as already described, the portion having a high electrical resistance 107 is formed by reducing the corresponding portion of the transparent electrode layer. The description of the formation of this portion will be made in the case of using the apparatus for the electrolytic treatment shown in Figure 2 (a). The photo-voltaic element 200 is immersed in the electrolytic solution 207 contained in the container for the electrolytic treatment ¿üb. The substrate 201 of the photovoltaic element 200 which serves as an electrode in the electrolytic treatment, is electrically connected to the negative terminal of the power source 209 and the counter electrode 208 is electrically connected to the positive terminal of the power source. This system is designed so that a bias voltage is printed in a forward direction towards the photovoltaic element 200. When a polarization energy is applied between the two electrodes, an electric current flows in the electrolytic solution 207 so that it preferably passes through the defect portions 205 having a low electrical resistance, where nascent hydrogen is generated on the side of the negative electrode, which serves as an originating side of the photovoltaic voltage for coupling the portions of the transparent electrode layer 204 which are located on the portions with defect 205, during the chemical reaction, specifically, in the reduction reaction. When the reduction reaction has been carried out, the product of the reaction successively dissolves in the electrolytic solution, where each of the portions of the transparent electrode layer included in the reduction reaction are thinner or disappear, by of which the trajectory of the electric current to be flowed in the defective portions in a direction transverse to the clinical path I n? ln >;? t. an.-pa t ent are substantially disconnected. The application of the previous electric field in the photovoltaic element during the electrolytic treatment can also be carried out using the apparatus for the electrolytic treatment shown in figure 2 (b), where light irradiation is carried out instead of the bias voltage . In this case, the electromotive force that is generated in the photovoltaic element due to the irradiation of the light on it becomes an applied polarization. In this case, the conditions for the polarization thus applied can be controlled in a suitable manner by adjusting the intensity of the light that is radiated. Next, description will be made of the prevention of desquamation of the metallic layer 102a in the present invention. As already described, the metal layer 102a as a constituent of the lower electrode layer 102 is preferably formed with Al or AlSi. For this case, the present inventors found that the metallic layer (consisting of aluminum material such as Al or AlSi) is susceptible to the desquamation of the layer due to the presence of halogen ion, particularly of Cl ion. , when the treatment is carried out using an acidic or alkaline solution depending on the state of the formation of the film for the metallic layer.To avoid this problem from occurring it is necessary to take due care as regards film formation temperature and speed However, it is extremely difficult to effectively form a desirable metallic layer (made of an aulimmium material such as "Alo i") capable of efficiently reflecting light in an amount of improved light reflection and that exhibits a sufficient adhesion and that is hardly removable.The phenomenon of desquamation of the layer, described in the above, is very likely to occur for Particularly at the interface between the metallic layer 102a and the transparent and electrically conductive layer 102b and / or at the interface between the metallic layer 102a and the user i 01. Through the experimental studies, the present inventors found that in order to prevent the desquamation rate of the metallic layer 102 a due to the Cl ions ", it is effective that the concentration of the Cl ion" is preferably controlled at 0.1 moi / 1 or less, more preferably at 0.03 moi / 1 or less. In any case, to avoid the phenomenon of desquamation of the metal layer 102a, the use of a di m form is considered; nu -a chuc n t r c. of the hydrogen ion by decreasing the concentration of the electrolytic solution that is used in the electrolytic treatment by diluting it with water or the like, or a way of extremely increasing the speed of the electrolytic treatment during the electrolytic treatment. However, any of these forms is problematic. Particularly in the first method it is difficult to achieve a concentration in the electrolytic solution sufficient to make the reduction of the corresponding portions of the transparent electrode layer as desired. For the last method, it is difficult to complete the electrolyte treatment including subsequent treatment steps, such as transportation and washing steps within a short period of time. Furthermore, in the case of using an aqueous electrolytic solution, it is difficult to avoid contamination of the Cl ion by a small amount.In this circumstance, the present inventors found that the use of a protective ion is effective, for example, to prevent The metallic layer (composed of an aluminum material such as Al or AlSi) is descaled in an atmosphere containing a chloride, it is effective to add sulfate, nitrate, chromate, acetate, benzoate or oxalate in it. way of using an aqueous solution of a particular acid or salt containing any of these salts as the electrolytic solution during the electrolytic treatment or a way of using an aqueous solution of one or more of these salts as ao-oo " . or i cct r ol 11; ca In the case that the metallic layer is composed of another metal other than Al, the addition of OH ions, NO ions, SO.A ions or C104 ions is also effective. Next, the present invention would be described in more detail in connection with the examples which are for illustrative purposes only and are not intended to restrict the scope of the present invention.

Example 1 In this example a plurality of solar cells of the triple cell type with spigot joints having the configuration as shown in Fig. 1 (a) and 1 (b) was prepared as will be described below. On a clean substrate coil made of SUS430BA (stainless steel) of 125 μ of thickness as the substrate 101, a double layer lower electrode layer 102 was formed consisting of an A1 layer of 1000A of thickness 102a and a layer of .nO of 1 μ of thickness 102b by means of a conventional cathodic sublimation process. Next, a semiconductor photoelectric conversion layer having a base cell 103 comprising an a-Si layer n of 400 A thick / a layer of type a-SiGe of type i of 1000 was formed on the lower electrode layer. Á of thickness / a C-Si layer of p-type of 100 A thick, an intermediate cell 103 comprising an a-Si layer of type n of 400 Á of thickness / a layer of a-SiGe of type i of 900 A thick / one layer of Si-type p 100 A thick, and a supcior cell 1 3 comprising a layer consisting of a -;.? of t i μt n of 100? of thick / a layer of a-Si of type I of 1000 A of thickness / a layer of μc-Si of type p of 100 A of thickness stacked in the order mentioned from the side of the substrate by means of a CVD process of conventional plasma, wherein the n-type layer n in each of the three stages was formed from a mixture of gas xH of gas PH3, of gas H7; the μc-Si layer of type p in each of the three cells was formed from a mixture of gas S1H4, gas HJ and gas IA; the a-SiGe layer type 1 in each of the lower and intermediate cells was formed from a mixture of gas S1H4, gas GeH4 and gas H2; and the a-Si layer of type y in the upper nip cell was formed from a mixture of S1H4 gas and H2 gas. Then, on the μc-Si p-type layer of the upper cell 123 of the photoelectric conversion semiconductor layer, a 1T0 film of 700A thickness was formed as the 1 apa e..l pj.at 1 a * sμ .it er.te _ 0 (by means of a process of evapora ^ rr ttrr.oi 1 es..ster.te cor.ver.c_cr.al.

Through this, c -? O _.r. fotovcitá co element formed on the coil of the substrate. The stainless steel substrate coil having the photovoltaic element formed therein was cut out to obtain a plurality of photovoltaic elements of 31 cm x 31 cm in size. The periphery of each photovoltaic element was subjected to the chemical etching treatment in a conventional manner to remove the 1T0 film as the transparent electrode present in u per i lo, by means of which a photovoitic element having a square active area was obtained Power generation of 30 cm x 30 cm in size. The resulting photovoltaic element (200, see Figures 2 (a) and 2 (b)) were placed in the electrolytic treatment apparatus shown in Figures 2 (a) and 2 (b)) with an electrolysis solution 207 which contains 20% by weight of an aluminum sulphate octahydrate and which has a conductivity o_ecl? The temperature of the liquid at 25 ° C, where the stainless steel substrate side of the photovoltaic element was electrically connected On the negative side of the power source 209, the counter-electrode 208 of the stainless steel substrate of the photovoltaic element was electrically connected to the positive side of the power source 209, and the interval between the counter electrode 208 and the stainless steel substrate of the photovoltaic element was .0 cm. Then, the photovoltaic element was subjected to the electrolytic treatment, where a cycle of application of a pulse voltage of 5.0 V was repeated five times during 0.3 seconds in an application interval of 0.1 second. The photovoltaic element thus treated was removed from the apparatus for electrolytic treatment, and was subjected to washing and drying in a conventional manner. The sum of the time that was occupied for the olympic treatment, the washing and drying lue de? minutes After this, an electrically insulating adhesive tape (not shown in the figure) was fixed in the peripheral region of the photovoltaic element where there was no 1TO film present. Then, a copper sheet like the bus bar 108 was arranged on the insulating adhesive tape located at each of the opposite end portions of the photo-voltaic element. Successively, a plurality of copper wires covered by a carbon paste as the. grid electrode l? i >; it was distributed separately on the surface of the photovoltaic element to make contact with the busbar 108 as shown in Fig. 1 (b), followed by the thermocompression bonding treatment using the conventional temper-compression bonding apparatus, by means of which they joined on the surface of the photovoltaic element. Then, a copper strip as the positive side power output terminal 109 was fixed to the busbar 108 by means of welding, and a copper strip as the energy output terminal of the negative side 110 was fixed to the substrate stainless steel of the photovoltaic element by means of welding, i'oi this means was obtained a solar cell of the configuration shown in figures l (a) and Kb). In this way a plurality of solar cells was prepared. The resulting solar cells were subjected to the evaluation as will be described later.

Comparative Example 1 The procedures of Example 1 were repeated, where first the plurality of photovoltaic elements was prepared and then a plurality of solar cells was prepared using the photovoltaic element, except that the electrolytic treatment of each of the photovoltaic elements was performed before of preparing a solar cell under the following conditions- The electrolytic solution used in example 1 was replaced by an electrolytic solution containing 10% by weight of an aluminum chloride nexahydrate with an electrical conductivity of 64.0 mS / cm and a chlorine ion content of U.4 mol / 1. And while the electrolytic solution was maintained at 25 ° C in which the photovoltaic element was immersed in the apparatus for the electrolytic treatment, the photovoltaic element was subjected to the electrolytic treatment, wherein the application cycle of a pulse voltage of 5.0 V for 0.3 seconds in an application interval of 0.1 second was repeated 5 times. The resulting solar cells were subjected to the evaluation as described below. : n.uao ion.

Evaluation The solar cells obtained in Example 1 and Comparative Example 1 were evaluated with respect to the initial characteristics (external appearance, derivation resistance, voltage generation characteristics and photoelectric conversion efficiency), and characteristics (external appearance) , strength in vacuum, voltage generation characteristic and photoelectric conversion efficiency) after a fatigue limit, as will be described below. 1. Evaluation of external appearance: In each of the solar cells obtained in Example 1 and Comparative Example 1, using a microscope, its initial external appearance was observed to see if there was flaking of the layer at the interface between the layer of Ai and the layer nü as the lower electrode layer and whether or not there was a portion of thick or colorful layer that would eventually come off, even in the case where the backing must be accompanied by a portion neither exposed nor peeling the cap. The result observed in each case is described in Table 1. 2. Evaluation of the resistance in derivation: In each one of the solar cells obtained in the Example 1 and 1 of Comparative Example I, using a conventional oscilloscope, its characteristics V-C (voltage-current characteristics) were measured in the dark to obtain a curve of the characteristics V-C. A resistance in derivation was obtained based on the gradient near the origin of the curve of characteristic V-C. In this way, derivation resistances were obtained for the solar cells in each case, and an average value between the derivation resistances obtained. The resultant average resultant resistance obtained in each case is shown in Table i. 3. Evaluation of the voltage generation characteristic: In this evaluation, for each of the solar cells of Example 1 and those of Comparative Example 1, the voltage generation characteristic with low intensity illumination was examined in the following manner. Each of the solar cells was subjected to fluorescence irradiation from a fluorescent lamp while the illuminance was varied in the range of 0 to 10,000 lux, where the voltage generated with the irradiance of the fluorescence was measured with an illuminance of 200 lux in a conventional way. In this way, voltages generated for the solar cells were obtained in each case, and an average value between the resulting voltages was obtained. The resulting average voltage value obtained in each case is shown in Tabia 1. 4. Evaluation of photoelectric conversion effciency: For each of the solar cells of Example 1 and those of 1, Comparative Example evaluated its initial photoelectric conversion efficiency in the following manner. The solar cell was placed in a solar simulator SPI-SUN SIMULATOR 240A (AM 1.5) (trade name produced by SPIRE Company), where a spectrum of pseudo solar light of 100 mW / cm was irradiated to the solar cell and the V-C characteristics were measured to obtain a curve of the V-C characteristics. Based on characteristic curve V-C, sc obtained the photoelectric conversion efficiency. In this way, photoelectric conversion efficiencies were obtained for the solar cells, and an average value between the photoelectric conversion efficiencies was obtained in each case. The average initial photoelectric conversion efficiency of Example I and Comparative Example 1 are shown collectively in Table 1. The conversion efficiency 1 ofoe. The starting point, average of Example i as shown in step 1, is a relative value with respect to Comparative Example I, which is set to 1.00.

. Evaluation of the characteristics (external appearance, resistance in derivation, voltage generation characteristic and photoelectric conversion efficiency) after a fatigue limit: Each of the solar cells of Example 1 and those of Comparative Example i that were used in the Previous evaluations were subjected to resin sealing by a conventional lamination form using resin materials for sealing in order to convert them into a solar cell module. By this, a plurality of solar cell modules was obtained for Example 1 and Comparative Example 1. For each of the solar cell modules thus obtained, the temperature and humidity cycle test was performed according to the A-test. 2 of the temperature cycle and the solar cell modules of the critalin series prescribed in the JISC8917 standard, as follows. The solar cell module was placed in a thermohydrate capable of controlling the temperature and humidity of a sample, where the solar cell module was subjected to the alternate repetition of a cycle of exposure to an atmosphere of -40 ° C for one hour and a cycle of exposure to an atmosphere of ü50C tíy¿ HR for 22 hours, 20 times. In each of the solar cell modules thus treated during the temperature and humidity cycle test, the evaluation was made regarding the external appearance, bypass resistance, voltage generation characteristic and photoelectric conversion efficiency in the same way as was described for evaluations 1 to 4 above. The results of the evaluation with respect to external appearance, resistance in derivation and efficiency in photoelectric conversion after the fatigue limit are shown collectively in labia i. The results of the evaluation with respect to the voltage generation characteristic are shown in the graph of Figure 3. Each of the values of resistance in derivation after the fatigue limit shown in Table 1 is a value relative to the corresponding average initial derivative resistance, which is set at 1.0. In the same way, each of the photoelectric conversion efficiency values after the fatigue limit shown in Tab 1 is a value relative to the conversion efficiency fot or > I Correct initial average, e. which is set in 1.0.

Table 1 characteristic initial characteristics after the fatigue limit manage resistance. Efficiency of appearance resistance efficiency in generator of external conversion in derivation external conversion derivation. voltage to 200 photoelectric (# 2) photoel? crrlc (kO-crA Lux (V) (# 11. * 2 Example there was no 200 < OR 1.20 V i little 1.13 r.o ubo 0.98 0.9? 1 of . { little variation! s carnation flake variation. layer layer layer Example there was 80 < Or 0.28 V (many l.CD r.en or 0.85 compare desquamation (pucna variation! Er. The tivo 1 de variació des amaciónción layer d sprendi ie r.-o initial layer # 1: the worth of example Comparative 1 is normalized to 1. 0 # 2: a relative value for the initial value that is set to 1.0, Based on the results shown in Table 1 and also in Figure 3, the following facts are understood. Any of the solar cells that were obtained in Example 1 is apparently superior to those obtained in Comparative Example i in terms of the initial characteristics and the characteristics after the fatigue limit through the temperature and humidity cycle test. Particularly, the solar cells obtained in Comparative Example 1 are inferior in bypass resistance and not satisfactory in photo-logical conversion efficiency. In ras déla. The solar cements obtained in Comparative Example 1 were found with peeling of the layer under the metallic wires as the grid electrode., and due to this, derivation or short circuit was found in these solar cells. Furthermore, in any of these solar cells it was found that a portion of the bulging layer was present even in the area where the backing is not exposed, and due to this abnormal energization occurred. In addition, its bypass resistance and photoelectric conversion efficiency after the fatigue limit was lower. For these reasons it is considered that the portion of the bulky layer present in it finally came off due to moisture and thermal shrinkage. On the other hand, none of the solar cells obtained in Example 1 presented these problems. Particularly, these solar cells are satisfactory in terms of external appearance, characteristics required for a solar cell, reliability and redeeming E j em 1 or 2 The procedures of Example 1 were repeated, where first a plurality of photovoltaic elements was prepared and then a plurality of solar cells were prepared using the photovoltaic element, except that the electrolytic treatment for each of the photovoltaic elements before the preparation of a solar cell was carried out under the following conditions. The electrolytic solution used in Example 1 was replaced by an electrolytic solution containing 2 * by weight of an aluminum acetate hexahydrate and with an electrical conductivity of 40.0 mS / cm and chlorine ion content of 0.03 mol / i or less. And while the electrolytic solution was maintained at 25 ° C in which the photovoltaic element was immersed in the apparatus for the electrolytic treatment, the rotovoltaic element was subjected to the electrolytic treatment, wherein the application cycle of the impulse voltage of 5.0 V during 0.3 seconds in an up- range. _ ^. _or;? from . _. mowing was repeated 5 times.

The resulting solar cells were subjected to the evaluation with respect to their initial characteristics in the same way as in Example 1 and Comparative Example 1. The results of the evaluation showed that the external appearance did not present a defect such as peeling of the layer or the like, the average initial voltage generation characteristic with the fluorescence irradiation with the 200 lux illuminance was 1.21 V which is very good, and the photoelectric conversion efficiency: .nic: ai average was 1.13 , which is very good, in terms of a relative value to the Shared Example 1, which is set to 1.0.

Example 3 The procedures of Example 1 were repeated, where first a plurality of photovoltaic elements was prepared and then a plurality of solar cells were prepared using the element; tovoi tá: co, except that the electrolytic treatment was carried out for each of the photovoltaic elements before preparing a solar cell under the following conditions. The electrolytic solution used in Example 1 was replaced by an electrolytic solution containing 20% by weight of a manganese sulfate hexahydrate and having an electrical conductivity of 40.0 mS / cm and a chlorine ion content of 0.03 mol / 1 or show us And while the electrolytic solution was maintained at 25 ° C in which the photovoltaic element was immersed in the apparatus for electro treatment! The ICO, CL element 1 ot.ovol taico was subjected to the electrolytic treatment, wherein a cycle of application of a pulse voltage of 5.0 V for 0.3 seconds at an application interval of 0.1 seconds was repeated 5 times. The resulting solar cells were subjected to evaluation with respect to their initial characteristics in the same manner as in Example 1 and Comparative Example 1. The results of the final evaluation were that an external appearance without defects such as desquamation was achieved. of the layer or the like, the characteristic of voltage generation with the fluorescence irradiation with the illuminance d 200 lux was 1.21 V which is very good, and the average initial photoelectric conversion efficiency was 1.14, which is very good, in terms of a relative value to Comparative Example 1, which is set to 1.0.

EXAMPLE 4 The procedures of Example 1 were repeated where first a plurality of photovoltaic elements was prepared and then a plurality of solar cells were prepared using the photovoltaic element, except that each of the photovoltaic elements before being subjected to the electrolytic treatment was irradiated with light of an intensity of 100 m / ciA from a metal halide lamp for 60 seconds. The cells. ' the ies i e., n! I an. The evaluation with respect to its initial characteristics is in the same way as in Example 1 and Comparative Example 1. The results of the evaluation showed that an external appearance without defect was achieved as peeling of the layer or the like , the average initial voltage generation characteristic with the irradiance of fluorescence with the illuminance of 200 lux was 1.22 V which is very good, and the olicienca of _O.VI '! Ü.C. The average initial lottery was 1.13, which is very good, in terms of a value relative to Comparative Example 1, which is set to 1.0.

Example 5 The procedures of Example 1 were repeated except that the electrolytic solution used in the photovoltaic electrolytic treatment was bb used in a plurality of different electrolyte solutions each with an electrolyte solution used in Example 1 to which a prescribed amount of potassium chloride was added to have a different chloride ion content in the range of 0.007 to 5,000 mol / i, by means of which a plurality of solar cells was obtained for each of the electrolytic solutions. The resulting solar cells were subjected to the evaluation with respect to their initial external appearance, their initial derivation resistance in terms of average value, the initial photoelectric efficiency in terms of the average value and the photoelectric conversion efficiency after the limit. e of fatigue by testing the temperature and humidity cycle in terms of the average value, respectively, in the same manner as in Example 1 and Comparative Example 1. The results of the evaluation are shown collectively in Table 2. Each of the average photoelectric conversion efficiency values _.n_.c? ul as shown in Table 2 is a value relative to the average initial photoelectric conversion efficiency in the case of using the 0.050 mol / 1 electrolytic solution in the content of the chlorine ion, which is set to 1.00. Each of the average photoelectric conversion efficiency values after the fatigue limit shown in Lab 2 is a relative value to the corresponding average initial photoelectric conversion efficiency, which is set to 1.00.

Table 2 Appearance content efficiency resistance of external chlorine ion derivation conversion conversion initial photoelectric photoelectric initial (value after a relative) fatigue limit (relative value) (# 1) there was no 230 1.06 0.99 desquamation of layer 0.010 there was no 219 1.06 0.99. peeling of the 0.030 layer there was no 1.05 0.99 peeling of the layer 0.40 portions 2 or: 1.02 0.98 colorful and dotted 0.050 portions 200 1.00 0.975 colorful and dotted 0.070 portions 0.96 0.97 colorful and dotted 0.100 percent 60 0.94 0.9ii color and with puts 0.200 portions 1 0. 0.93 0.95 color and with points 0.500 there were 70 0.89 0.90 desquamation of layer 1.000 there were 50 0.07 0.87 desquamation of layer 2.000 descaling 45 0.83 0.83 tion means iva of the layer 5.000 descama 10 0.77 0.00 mean tiva of the layer Based on the results shown in Table 2, the following facts are understood. By using a specific electrolytic solution with a chlorine ion content of 0.033 moi / 1 or less in the electrolytic treatment of a photovoltaic element, during the production of a solar cell, a highly reliable solar cell can be produced, free of layer desquamation in «__ t ..? _: 1 to i. o .. I c .ac of Al and the ZnO layer as the lower eiectrodica layer and also at the interface between the substrate and the Al layer and which is satisfactory in bypass resistance and photoelectric conversion efficiency and with high performance. Particularly, any of the solar cells that were produced using the specific electrolytic solution is free of derivation and short circuit and also free of abnormal energization which would occur due to the peeling of the layer.

Claims (7)

1. REINVI DICA IUNES A process for producing a photovoltaic element, the process consists of the steps of: providing a photovoltaic element consisting of (a) a lower eietrodic layer containing (ai) a metal layer consisting of aluminum or an aluminum compound and ( a-ii) a transparent and electrically conductive layer, (b) a semiconductor layer of photoelectric conversion, and (c) an electrically conductive layer stacked in the aforementioned order on the substrate, and the immersion of the photovoltaic element in an electrolytic solution for neutralizing a short-circuited current path defect present in the photovoltaic element by means of the action of an electric field, wherein the electrolytic solution has a chlorine ion content of 0.03 mol / l or less.
2. The process, according to claim 1, where the solution e. ect r 1 i 1.1 ca contains a prtector ion capable of preventing the appearance of desquamation of the layer at the interface between the metal layer (a-i) and the substrate or the transparent and electrically conductive layer (a-ii).
3. The process, according to claim 2, wherein the protective ion is an ion based on at least one compound selected from the group consisting of sulfate, nitrate, chromate, acetate, benzoate and oxalate.
4. 4. The process of acuet o with the re i u i nd i cation 1, where the electric field is an electric field generated by applying a polarization energy in the photovoltaic element.
5. 5. The process, according to claim 1, wherein the electric field is an electric field generated by an electromotive force, particularly a volatile characteristic of the photovoltaic element that is generated by means of irradiating light in the photo-voltaic element.
6. 6. The process, according to reinvmdication 4, wherein the polarization energy is applied in a forward direction in the photovoltaic element.
7. 7. The process, according to claim 1, wherein the substrate is constituted by a material that is selected from the group consisting of metals, glass, ceramics and resins. 0. The process, according to coi. the reinvindication 1, wherein the substrate is of large substrate, and a large substrate having a photovoltaic element in it is continuously passed through the electrolytic solution. reinvindication 1, wherein the aluminum compound contains silicon The process, according to claim 1, wherein the transparent and electrically conductive layer (a-ii) and / or the transparent layer (c) consist of a metal oxide i The r ced of n < ... o? d .. vi. the i nv i nd i falls i On 1, where the semiconductor photoelectric conversion layer (b) consists of a non-monocrystalline semiconductor material. process, according to claim 1, wherein the treatment with the electrolytic solution is carried out before the desquamation of the layer begins at the interface between the metallic layer (ai) and the substrate or the transparent and electrically conductive layer (a- _ i).