Bifacial thin-film solar cell and manufacturing method thereof

Abstract

The present invention relates to a bifacial thin-film solar cell and a manufacturing method thereof, wherein, in implementing a CIGS-based bifacial thin-film solar cell, the interfacial resistance and recombination characteristics at an interface between a rear transparent electrode and CIGS are improved, thus making it possible to enhance rear-side photovoltaic performance. The bifacial thin-film solar cell according to the present invention is characterized by comprising: a rear transparent electrode stacked on a transparent substrate; a rear passivation layer stacked on the rear transparent electrode; a conductive thin film pattern formed in a partial region on the rear passivation layer; a light absorption layer stacked on the front surface of the rear passivation layer including the conductive thin film pattern; a buffer layer stacked on the light absorption layer; and a front transparent electrode stacked on the buffer layer.

Description

Double-sided light-receiving thin-film solar cell and its manufacturing method

[0001] The present invention relates to a double-sided light-receiving thin film solar cell and a method for manufacturing the same, and more particularly, to a double-sided light-receiving thin film solar cell and a method for manufacturing the same, which can improve the photovoltaic performance of the rear side by improving the interfacial resistance and recombination characteristics at the interface between a rear transparent electrode and CIGS in implementing a CIGS-based double-sided light-receiving thin film solar cell.

[0002] [Description of Nationally Supported Research and Development]

[0003] This research was supported by the Ministry of Science and ICT and the National Research Foundation of Korea [Research Project Name: Climate Change Response Technology Development, Research Project Name: CIGS Thin Film Solar Cell-Based High-Efficiency Translucent Solar Cell Module Source Technology, Project Identification Number: 1055001324, Project Number: 2019M1A2A2072412].

[0004] CIGS (Cu(In 1-x ,Ga x )(Se,S)2) thin-film solar cells are attracting attention as high-efficiency thin-film solar cells due to their high photovoltaic efficiency of up to 23.5% and excellent stability. In addition, CIGS thin-film solar cells can change the band gap by 1.0-1.7 eV compared to silicon solar cells with a fixed band gap of 1.1 eV, making them easy to apply to various usage conditions. In addition, they have excellent electro-optical characteristics and are flexible and lightweight, making them suitable for various applications in buildings, automobiles, and military applications.

[0005] Meanwhile, bifacial solar cells, which can generate photovoltaic power from both the front and back surfaces of a solar cell, are a technology that can improve the photovoltaic performance of solar cells. In the case of CIGS thin-film solar cells, bifacial solar cell configurations can be realized by replacing the Mo-based rear electrode with a transparent conductive oxide (TCO). For example, a bifacial solar cell can be realized by sequentially stacking a rear TCO, a light-absorbing layer (CIGS), a buffer layer, and a front TCO on a glass substrate.

[0006] However, double-sided photovoltaic cells of this structure have the following problems: work function mismatch between TCO and CIGS, and GaO precipitated from CIGS and formed at the interface between the back TCO and CIGS. x There are problems such as high interfacial resistance due to the back, poor carrier transport characteristics due to defects, and high electron-hole recombination characteristics, resulting in very low photovoltaic performance on the back side. Therefore, there is a need to improve the back interfacial resistance and back recombination characteristics.

[0007] First, to improve the rear interface resistance characteristics, a thin Mo film layer or GaO film is applied between the rear TCO and CIGS. x To suppress the formation of , methods such as lowering the process temperature of the CIGS photoactive layer to below 400℃ have been proposed. These methods were very effective in reducing the rear interface resistance. However, there is no evidence that the above methods for lowering the interface resistance are effective in suppressing rear recombination.

[0008] As a method for improving the back recombination characteristics, a method has been proposed to form a CIGS light-absorbing layer with a composition distribution that increases the Ga / (Ga+In) ratio so that a bandgap gradient occurs in the direction of the back TCO when forming the CIGS light-absorbing layer. This method was confirmed to improve the photocurrent due to back-side light incidence, and the principle is to suppress recombination by pushing the photoexcited electrons formed in the CIGS light-absorbing layer near the interface away from the interface through the bandgap gradient. However, this does not passivate the interface itself, so there is a limit to completely suppressing interfacial recombination (see Efficiency boost of bifacial Cu(In,Ga)Se2 thin-film solar cells for flexible and tandem applications with silver-assisted low-temperature process (Nature Energy, v.8, p.40-51, 2023).

[0009] Another method is to have Ga2O3 formed at the interface between the back TCO and CIGS act as a passivation layer, and to disperse conductive metal nanoparticles within the Ga2O3, thereby expecting a passivation effect by Ga2O3 and an interface resistance improvement effect by the metal nanoparticles dispersed within the Ga2O3 (Korean Patent No. 2009308). However, Ga2O3 formed as a byproduct during the heat treatment process of the CIGS light-absorbing layer acts as a factor of high interface resistance and defects as discussed above, and therefore the passivation effect by Ga2O3 is bound to be limited.

[0010] Meanwhile, although not related to a double-sided photovoltaic cell, US Patent Publication No. US 2018-0138347 proposes a structure for improving the back passivation characteristics and electrical characteristics, in which a light-reflecting metal layer (104), an Al2O3 passivation layer (106), a light-absorbing layer (102), a buffer layer (802), and a transparent electrode (804) are sequentially laminated on a substrate, and electrical contacts (108) are provided in a plurality of openings penetrating the Al2O3 passivation layer (106). Through this structure, it is described that the back passivation characteristics by the Al2O3 passivation layer and the electrical characteristics by the electrical contacts (108) that induce ohmic contact between the light-absorbing layer (102) and the light-reflecting metal layer (104) can be expected to be improved. The technology disclosed in US 2018-0138347 shares some technical objectives with the present invention in terms of improving rear passivation characteristics and electrical characteristics, but there are clear differences in whether it is a double-sided light-receiving type, the constituent materials of the rear passivation layer, and the bonding structure of the rear passivation layer and the conductive thin film pattern, which will be described in the description of the present invention below.

[0011] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a double-sided light-receiving thin-film solar cell and a manufacturing method thereof, which can improve the photovoltaic performance of the rear side by improving the interfacial resistance and recombination characteristics at the interface between the rear transparent electrode and CIGS in implementing a CIGS-based double-sided light-receiving thin-film solar cell.

[0012] In order to achieve the above object, a double-sided light-receiving thin film solar cell according to the present invention is characterized by comprising: a rear transparent electrode laminated on a transparent substrate; a rear passivation layer laminated on the rear transparent electrode; a conductive thin film pattern formed on a portion of the rear passivation layer; a light absorption layer laminated on the entire surface of the rear passivation layer including the conductive thin film pattern; a buffer layer laminated on the light absorption layer; and a front transparent electrode laminated on the buffer layer.

[0013] The above rear passivation layer is TiO x or TaO x It consists of.

[0014] TiO x The electrical resistivity is greater than 1 Ωcm.

[0015] The above rear passivation layer is TiO doped with any one element of Nb, Sb, or S. x or TaO x It consists of.

[0016] TiO doped with any one of the elements Nb, Sb, or S x The electrical resistivity is greater than 1 Ωcm.

[0017] The conductive thin film pattern is in the form of a dot or a line, and a plurality of conductive thin film patterns are spaced apart and arranged on the rear passivation layer.

[0018] The total area of ​​the plurality of conductive thin film patterns does not exceed 20% of the area of ​​the rear passivation layer.

[0019] When the conductive thin film pattern is in the form of a dot, the conductive thin film pattern has a length or diameter of 0.1 to 2 ㎛, a thickness of 0.1 to 2 nm, and the distance between the conductive thin film patterns is the carrier diffusion length (L) in the light absorption layer. D ) is equal to or less than.

[0020] When the conductive thin film pattern is linear, the width of the linear conductive thin film pattern is 0.1 to 2 ㎛, the thickness is 0.1 to 2 nm, and the distance between the conductive thin film patterns is the carrier diffusion length (L) in the light absorption layer. D ) is equal to or less than.

[0021] The conductive thin film pattern is made of molybdenum (Mo).

[0022] The thickness of the back passivation layer is 2 to 4 nm.

[0023] The light absorbing layer is CIGS(Cu(In 1-x , Ga x )(Se,S)2).

[0024] The back transparent electrode and front transparent electrode are made of one of indium oxide, zinc oxide, and tin oxide, and the indium oxide is InO x , ITO, (W, Ce, Mo)-doped InO x , IZO, and zinc oxide is (Al, Ga, B, Ti, F, H)-doped ZnO. x , and the tin oxide is (F, Sb)-doped SnO x am.

[0025] A buffer layer is provided between the light absorption layer and the front transparent electrode, and the buffer layer is made of one or a combination of CdS, InS(O,OH), ZnS(O,OH), ZnMgO, ZnTiO, and ZnSnO.

[0026] It has a light-transmitting region in which a front transparent electrode, a light-absorbing layer, and a rear passivation layer of a specific region are removed to expose the rear transparent electrode.

[0027] A P1 region is provided in which a rear passivation layer and a rear transparent electrode are removed by a certain area, a P2 region is provided in which a buffer layer and a light absorption layer are removed by a certain area, and a P3 region is provided in which a front transparent electrode, a buffer layer, and a light absorption layer are removed by a certain area. The rear transparent electrode of a neighboring cell is insulated by the P1 region, the rear transparent electrode and the front transparent electrode of a neighboring cell are connected by the P2 region, and the front transparent electrode of a neighboring cell is insulated by the P3 region.

[0028] A method for manufacturing a double-sided light-receiving thin-film solar cell according to the present invention is characterized by comprising the steps of: forming a back transparent electrode on a transparent substrate; sequentially laminating a back passivation layer on the back transparent electrode; forming a conductive thin film pattern on the back passivation layer; forming a light absorption layer on the entire surface of the back passivation layer including the conductive thin film pattern; and forming a front transparent electrode on the light absorption layer.

[0029] The step of forming a conductive thin film pattern on a back passivation layer includes a step of forming a mask on the back passivation layer that exposes a portion of the back passivation layer, a step of depositing a conductive metal on the entire surface of the back passivation layer including the mask, and a step of removing the mask to form a conductive thin film pattern on a portion of the back passivation layer.

[0030] It may further include a step of forming a light-transmitting region in which a front transparent electrode and a light-absorbing layer of a specific region are removed to expose a rear transparent electrode.

[0031] Before the formation of the light absorption layer, a conductive thin film pattern is formed on the back passivation layer, and a step of scribing the back transparent electrode and the back passivation layer along the P1 region to a certain area to divide them into a plurality of cells and insulate the back transparent electrodes between neighboring cells may be further included.

[0032] After forming the light-absorbing layer, the method may further include a step of scribing the light-absorbing layer along the P2 region to expose the rear passivation layer.

[0033] In a state where the front transparent electrode is laminated, the step of scribing the front transparent electrode and the light absorption layer along the P3 region to insulate the front transparent electrode between neighboring cells may be further included.

[0034] The double-sided light-receiving thin-film solar cell according to the present invention has the following effects.

[0035] The combination structure of the back passivation layer and the conductive thin film pattern can improve the back passivation characteristics and back interface resistance characteristics, thereby improving the photocurrent characteristics due to back light incidence of a double-sided light-receiving thin film solar cell.

[0036] Figure 1 is a configuration diagram of a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention.

[0037] Figures 2 and 3 are reference drawings showing the shape of a conductive thin film pattern according to one embodiment of the present invention.

[0038] FIGS. 4A to 4D are process cross-sectional views for explaining a method for manufacturing a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention.

[0039] FIG. 5 and FIG. 6 are reference drawings showing a cross-sectional view of regions P1 to P3 and a plan view of a light-transmitting region (T) of a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention.

[0040] Figures 7a and 7b are experimental results showing the current-voltage characteristics at front and rear light incidence according to Experimental Example 1.

[0041] Figures 8a and 8b are experimental results showing the current-voltage characteristics at front and rear light incidence according to Experimental Example 2.

[0042] Figures 9a and 9b are the TEM-EDS analysis results of ITO / TiO2(4 nm) / CIGS manufactured by Experimental Example 1.

[0043] Figures 10a and 10b are the TEM-EDS analysis results of ITO / TiO2(4 nm) / Mo(0.5 nm) / CIGS manufactured by Experimental Example 2.

[0044] Figure 11 shows the experimental results showing electrical resistivity characteristics according to oxygen content.

[0045] Figures 12a and 12b are experimental results showing the front and rear photocurrent characteristics of a thin film solar cell using TNO with an oxygen content of 0.08% and 0.2% in the sputtering Ar process gas.

[0046] Figures 13a and 13b are experimental results showing the front and rear photocurrent characteristics of a thin film solar cell to which a TNO and Mo thin film layer (0.5 nm) with an oxygen content of 0.08% and 0.2% in a sputtering Ar process gas is applied.

[0047] The present invention proposes a technology capable of maximizing the rear-side photovoltaic performance of a double-sided light-receiving thin-film solar cell by passivating defects existing at the interface between a back-side transparent electrode and a light-absorbing layer to minimize carrier recombination at the interface and simultaneously improving the ohmic contact characteristics between the back-side transparent electrode and the light-absorbing layer to facilitate the movement of holes (+) generated in the light-absorbing layer to the back-side transparent electrode.

[0048] To implement this, the present invention includes an n-type metal oxide, TiO, between the rear transparent electrode and the light absorption layer. x or TaO x A structure is proposed in which a back passivation layer is provided and a conductive thin film pattern is provided on the back passivation layer.

[0049] TiO x (or TaO x ) is provided between the rear transparent electrode and the light-absorbing layer to passivate defects present on the rear surface of the light-absorbing layer, thereby preventing electrons (-) generated in the light-absorbing layer from recombining with the defects and being annihilated.

[0050] The conductive thin film pattern is formed on a portion of the rear passivation layer and is inserted into the light absorption layer, and is made of TiO x (or TaO x ) minimizes the interfacial resistance between the back passivation layer and CIGS, and induces ohmic contact between the light absorption layer and the back transparent electrode.

[0051] That is, under the laminated structure of the back passivation and the conductive thin film pattern, the back passivation layer in the area where the conductive thin film pattern is not provided serves to passivate defects existing on the back of the light-absorbing layer, and the conductive thin film pattern provided on some area of ​​the back passivation layer serves to lower the interfacial resistance between the light-absorbing layer and the back passivation, thereby inducing ohmic contact between the light-absorbing layer and the back transparent electrode.

[0052] Typically, SiO2 or SiN is used to passivate the p+ region (p-type substrate or p-type emitter) in crystalline silicon solar cells. x Passivation layers of materials have been applied, and recently, Al2O3 has been proven to be very effective in passivating p-type emitters on n-type substrates. Al2O3 deposited on a silicon substrate acquires a large amount of negative fixed charges through heat treatment, and these charges are mainly located at the interface between the Al2O3 thin film and the crystalline silicon substrate, forming a very strong negative electric field in the p+ region of the silicon surface, thereby pushing photoexcited electrons away from the interface and exhibiting low recombination characteristics.

[0053] As such, Al2O3 is a very effective material as a passivation layer for the p+ region of crystalline silicon solar cells. Therefore, it is natural to consider applying Al2O3 as a passivation layer for CIGS-based thin-film solar cells. However, when applying Al2O3 as a passivation layer in crystalline silicon solar cells, a structure in which the electrode penetrates the Al2O3 is essential for ohmic contact between the electrode and the p+ region, because Al2O3 is an insulator. Therefore, when applying Al2O3 as a passivation layer to CIGS-based thin-film solar cells, penetration of the Al2O3 is also inevitably required for ohmic contact between the electrode and the light-absorbing layer. For this reason, applying Al2O3 as a passivation layer to CIGS-based thin-film solar cells is difficult. For reference, US 2018-0138347 presents a structure in which an Al2O3 passivation layer (106) is provided between a light-reflecting metal layer (10) and a light-absorbing layer (102) without a penetration portion, but the light-reflecting metal layer (10) is not an electrode on which carriers are collected.

[0054] In the present invention, as described above, TiO is used as a rear passivation layer of a CIGS-based thin film solar cell. x (or TaO x ) is applied. As is known, TiO x , TaO x Since TiO2 is an n-type material, it is theoretically unsuitable to apply an n-type material such as TiO2 to passivate CIGS, a p-type semiconductor. This is because when an n-type material is applied as a passivation layer to passivate the CIGS interface, hole (+) transport is blocked by the n-type passivation layer separately from passivation.

[0055] Despite this fundamental incompatibility, TiO x (or TaO x ) and a combination structure of a conductive thin film pattern and a back passivation layer, which causes carrier blocking, TiO x / The barrier at the CIGS interface can be eliminated. In addition, TiO x TiO is conductive, unlike Al2O3 which is an insulator. x It is possible to induce an ohmic contact between the back transparent electrode and the light absorbing layer without penetration of the back transparent electrode. That is, the back passivation characteristic is provided between the back transparent electrode and the light absorbing layer by TiO. x Achieved by, TiO x The interfacial resistance between the TiO and CIGS is resolved by the conductive thin film pattern. x TiO has conductivity and can be used to control the oxygen content (and / or impurity content). x By taking advantage of the ability to control the conductivity of TiO x It is possible to induce ohmic contact between the back transparent electrode and the light absorbing layer without penetration.

[0056] Hereinafter, a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0057] Referring to FIG. 1, a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention has a structure in which a rear transparent electrode (120), a rear passivation layer (130), a light absorption layer (150), a buffer layer (160), and a front transparent electrode (170) are sequentially laminated on a transparent substrate (110), and a conductive thin-film pattern (140) is provided on the rear passivation layer (130).

[0058] The light absorbing layer (150) absorbs light and generates electron (-) and hole (+) pairs through photoelectric conversion. The electrons (-) generated in the light absorbing layer (150) move to the front transparent electrode (170) and the holes (+) move to the back transparent electrode (120). At this time, the light absorbing layer (150) and the front transparent electrode (170) form a pn junction. In addition, the light absorbing layer (150) is formed of CIGS (Cu (In 1-x , Ga x )(Se,S)2).

[0059] The rear passivation layer (130) is provided between the rear transparent electrode (120) and the light-absorbing layer (150) to passivate defects present on the rear surface of the light-absorbing layer (150) and to minimize the annihilation of photo-excited electrons (-) formed in the region of the light-absorbing layer (150) that contacts the rear transparent electrode (120) from the light-absorbing layer (150) by recombination with the defects.

[0060] The rear passivation layer (130) is an n-type metal oxide, TiO x or TaO x It is composed of. In addition, TiO doped with any one element among Nb, Sb, and S. x or TaO x can also be applied as a back passivation layer (130). Most preferably, TiO is used as the back passivation layer (130). x or Nb-doped TiO x (TNO, titanium niobium oxide) can be applied. Below, for convenience of explanation, TiO x Let's explain based on this.

[0061] Although the light absorption layer (150) made of CIGS is a p-type semiconductor, TiO, which is an n-type metal oxide, is used as a passivation layer of the light absorption layer (150). x The reason for applying it is because these materials have excellent passive properties and can control conductivity.

[0062] In the previous section, ‘Background Technology of the Invention’, Al2O3 was mentioned as a representative passivation material for crystalline silicon solar cells. Although Al2O3 has excellent passivation properties, it is an electrical insulator, so in order for an electrode (e.g., a front electrode) to make an ohmic contact with a p-type semiconductor layer, the electrode must penetrate the passivation layer, Al2O3.

[0063] The energy band gap of Al2O3 is about 7.0 to 7.6 eV, making it an insulator, whereas TiO, an n-type metal oxide xIt has an energy band gap of about 3.2 eV and is conductive.

[0064] In this way, TiO, an n-type metal oxide x Unlike Al2O3, which is an insulator, TiO is conductive, so when applied as a passivation layer, penetration of the electrode through the passivation layer is not required. In addition, TiO x Regarding the passive properties of TiO, please refer to the experimental examples described below. x When applied with a thickness of 2 to 4 nm as a back passivation layer (130), TiO x It can be confirmed that the rear photoelectric conversion efficiency is increased by more than two times compared to when TiO is not applied, and these results are x This result proves that the rear passive characteristics have been improved.

[0065] The most important requirements for improving the photoelectric conversion efficiency of CIGS-based double-sided thin-film solar cells are the improvement of the rear recombination characteristics and the rear interface resistance characteristics, and TiO x This can be achieved by applying a back passivation layer (130) and providing a conductive thin film pattern (140) on the back passivation layer (130).

[0066] TiO x As described above, it is confirmed through experimental examples that the rear passivation characteristics, i.e., the rear recombination characteristics, are improved through application to the rear passivation layer (130) of TiO x Although TiO has conductivity, x The absolute electrical conductivity of TiO is not very good. In addition, TiO x Since TiO is an n-type material, it hinders the transport of holes (+) moving from the light absorption layer (150) to the rear transparent electrode (120). That is, TiO x There is an electrical resistance at the interface between TiO and CIGS. Therefore, x Although the application of only can improve the rear recombination characteristics, there is a limit to improving the rear interface resistance characteristics.

[0067] Considering these points, a conductive thin film pattern (140) is applied. That is, TiO x By providing a conductive thin film pattern (140) in some area of ​​the rear passivation layer (130) formed of the conductive thin film pattern (140), ohmic contact between the light absorption layer (150) and the rear transparent electrode (120) can be induced through the conductive thin film pattern (140), thereby improving the rear interface resistance characteristics.

[0068] At this time, the ohmic contact between the light absorption layer (150) and the rear transparent electrode (120) is possible even though the conductive thin film pattern (140) is not provided in a form that penetrates the rear passivation layer (130) but is provided on the rear passivation layer (130), because the rear passivation layer (130) is made of TiO, not Al2O3. x This is because it is made of. As in the crystalline silicon solar cell discussed above, when Al2O3 is applied as a passivation layer, penetration of the passivation layer of the electrode is required due to the non-conductive properties of Al2O3, but TiO x Unlike Al2O3, TiO has conductivity. x By controlling the thickness of the light absorbing layer (150), an ohmic contact between the light absorbing layer (150) and the rear transparent electrode (120) can be mediated. As another example, U.S. Patent Publication No. US 2018-0138347 discloses that a passivation layer (106) is formed of Al2O3, and that an electrical contact (108) penetrates the Al2O3 passivation layer (106) for electrical connection between the light absorbing layer (150) (102) and the light reflecting metal layer (104).

[0069] Also, TiO x The conductivity of TiO can be controlled through the oxygen content and impurity content, thereby controlling the ohmic contact between the light absorption layer (150) and the rear transparent electrode (120). x Conductivity control of TiO x It means the control of electrical resistivity of TiO xThe electrical resistivity of TiO must be controlled to be greater than 1 Ωcm, and for this purpose, TiO x In the case of sputtering-based deposition, the oxygen content in the process gas must be maintained above a certain ratio, for example, it is necessary to control it to 0.2 to 0.3%. Here, the impurity refers to any one of the elements Nb, Sb, and S.

[0070] As explained above, TiO x The rear recombination characteristics and rear interface resistance characteristics can be improved through the combination of the rear passivation layer (130) and the conductive thin film pattern (140), TiO x The back passivation layer (130) and the conductive thin film pattern (140) need to have an optimal structure. For example, if the area and volume of the conductive thin film pattern (140) provided in some area of ​​the back passivation are too large, the back interface resistance characteristic is improved, but the back recombination characteristic by the back passivation layer (130) is deteriorated, and if the area of ​​the conductive thin film pattern (140) is too small, the back recombination characteristic is improved, but the effect of improving the back interface resistance characteristic by the conductive thin film pattern (140) is minimal.

[0071] Considering these points, the conductive thin film pattern (140) is provided in a dot shape (see FIG. 2) or a linear shape (see FIG. 3), and the distance between the conductive thin film patterns (140) is the carrier diffusion length (L) in the light absorption layer (150). D ) should be set in consideration of the light transmittance, and the thickness of the conductive thin film pattern (140) should be designed in consideration of the light transmittance.

[0072] Specifically, when the conductive thin film pattern (140) is in the form of a dot, a plurality of conductive thin film patterns (140) are spaced apart from each other and arranged on the rear passivation layer (130), and the total area of ​​the plurality of conductive thin film patterns (140) should not exceed 20% of the area of ​​the rear passivation layer (130). If it exceeds 20%, the rear interface resistance characteristic is improved, but the rear recombination characteristic due to the rear passivation layer (130) is deteriorated.

[0073] In addition, the dot-shaped conductive thin film pattern (140) is preferably designed to have a length or diameter of 0.1 to 2 μm and a thickness of 0.1 to 2 nm for light transmission. In addition, the distance between the conductive thin film patterns (140) is the carrier diffusion length (L) in the light absorption layer (150). D ) should be equal to or smaller than 2∼5㎛.

[0074] When the conductive thin film pattern (140) is linear, the conductive thin film pattern (140) can be arranged in a grid shape, and the distance between the conductive thin film patterns (140) is the carrier diffusion length (L) in the light absorption layer (150). D ) is preferably designed to be equal to or smaller than 2 to 5 μm. In addition, it is preferable that the width of the linear conductive thin film pattern (140) be designed to be 0.1 to 2 μm, and the thickness be designed to be 0.1 to 2 nm for light transmission. The conductive thin film pattern (140) may be made of molybdenum (Mo) as an example.

[0075] Meanwhile, the rear transparent electrode (120) and the front transparent electrode (170) may be made of any one of indium oxide, zinc oxide, and tin oxide. The indium oxide is InO x , ITO, (W, Ce, Mo)-doped InO x , IZO, and zinc oxide is (Al, Ga, B, Ti, F, H)-doped ZnO. x , and the tin oxide is (F, Sb)-doped SnO x am.

[0076] Additionally, the buffer layer (160) may be formed of one or a combination of CdS, InS(O,OH), ZnS(O,OH), ZnMgO, ZnTiO, and ZnSnO.

[0077] Above, a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention has been described. Next, a method for manufacturing a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention will be described.

[0078] First, as shown in Fig. 4a, a rear transparent electrode (120) is laminated on a transparent substrate (110).

[0079] The transparent substrate (110) may be a glass substrate, and the rear transparent electrode (120) may be laminated using any one of sputtering, vacuum evaporation, and solution processes. In addition, the rear transparent electrode (120) may be formed of any one of indium oxide, zinc oxide, and tin oxide. The indium oxide is InO x , ITO, (W, Ce, Mo)-doped InO x , IZO, and zinc oxide is (Al, Ga, B, Ti, F, H)-doped ZnO. x , and the tin oxide is (F, Sb)-doped SnO x am.

[0080] Next, a rear passivation layer (130) is laminated on the rear transparent electrode (120). The rear passivation layer (130) can be laminated using any one of sputtering, vacuum evaporation, and solution processes, similar to the rear transparent electrode (120).

[0081] The rear passivation layer (130) is an n-type metal oxide, TiO x or TaO x TiO composed of or doped with any one of the elements Nb, Sb, or S x or TaO xIt can be made of. Most preferably, the rear passivation layer (130) is made of TiO x or Nb-doped TiO x (TNO) can be made of TiO x or Nb-doped TiO x To control the conductivity, i.e. electrical resistivity, of (TNO), TiO x or Nb-doped TiO x The oxygen content and / or impurity content of (TNO) is controlled, preferably TiO x The electrical resistivity of TiO must be controlled to be greater than 1 Ωcm, and for this purpose, TiO x During sputter deposition, the oxygen content in the process gas must be maintained above a certain level, and for example, it needs to be controlled to 0.2 to 0.3%.

[0082] In a state where the back passivation layer (130) is laminated, a conductive thin film pattern (140) is formed on the back passivation layer (130). Specifically, a mask is formed on the back passivation layer (130) to expose a portion of the back passivation layer (130) (see FIG. 4b). The mask can be formed using a photolithography or electron beam lithography process. Additionally, it can also be formed using a block copolymer mask material technology or a nano bead / sphere lithography process. Then, a conductive metal (140a), for example, Mo, which is a constituent material of the conductive thin film pattern (140), is deposited on the entire surface of the back passivation layer (130) including the mask. The conductive metal (140a) can be deposited using a sputtering or vacuum evaporation process, etc. Next, when the mask is removed, a conductive thin film pattern (140) is formed that exists only in a part of the rear passivation layer (130) (see FIG. 4c).

[0083] In the above process, when patterning a mask that exposes a portion of the rear passivation layer (130), the portion exposed by the mask may be in the form of dots or lines. In addition, the distance between dots or lines may be determined by the carrier diffusion length (L) in the light absorption layer (150). D ) should be equal to or smaller than 2∼5㎛, and it is preferable to pattern the mask so that the length of the dot or the width of the line is 0.1∼2㎛. In addition, the total area of ​​the area exposed by the mask should not exceed 20% of the area of ​​the back passivation. The area exposed by the mask corresponds to the area where the conductive thin film pattern (140) is formed, and if the total area of ​​the conductive thin film pattern (140) exceeds 20% of the area of ​​the back passivation, the back passivation characteristic by the back passivation layer (130) deteriorates. In addition, in the above process, when depositing the conductive metal (140a), it is preferable that the conductive metal (140a) be deposited with a thickness of 0.1∼2nm to secure light transmittance.

[0084] In a state where a conductive thin film pattern (140) is formed on a rear passivation layer (130), a light-absorbing layer (150) material, i.e., CIGS, is laminated on the entire surface of the rear passivation layer (130) including the conductive thin film pattern (140), and then heat treatment is performed to form a light-absorbing layer (150) (see FIG. 4d). When the formation of the light-absorbing layer (150) is completed, the conductive thin film pattern (140) takes the form of being included within the light-absorbing layer (150).

[0085] Next, when a buffer layer (160) and a front transparent electrode (170) are sequentially laminated on the light absorption layer (150), the manufacturing method of a double-sided light-receiving thin-film solar cell according to one embodiment of the present invention is completed. The buffer layer (160) may be formed of any one of CdS, InS(O,OH), ZnS(O,OH), ZnMgO, ZnTiO, and ZnSnO, or a combination thereof, and the front transparent electrode (170) may be formed of the same material as the rear transparent electrode (120).

[0086] Meanwhile, the double-sided light-receiving thin-film solar cell of the present invention can also be implemented in the form of a single integrated module. That is, it can be manufactured in a form in which multiple solar cells are provided on a single substrate. In this case, scribing (P1) for inter-cell insulation of the back transparent electrode (120), scribing (P2) for inter-cell connection of the back transparent electrode (120) and the front transparent electrode (170), and scribing (P3) for inter-cell insulation of the front transparent electrode (170) are required.

[0087] This is explained in detail as follows (see Fig. 5).

[0088] A back transparent electrode (120) and a back passivation layer (130) are sequentially laminated on a transparent substrate (110), and a conductive thin film pattern (140) is formed on the back passivation layer (130). Then, the back transparent electrode (120) and the back passivation layer (130) are scribed along a scribing line to a certain area to divide them into a plurality of cells, and the back transparent electrodes (120) between neighboring cells are insulated. At this time, the scribing line is referred to as a P1 region, and the back transparent electrode (120) is divided into a plurality of cells by the P1 region, and the back transparent electrodes (120) between neighboring cells are electrically insulated by the P1 region. The scribing process for the P1 region and the scribing process for the P2 region and the P3 region described below can be performed using a laser.

[0089] Next, a light absorption layer (150) and a buffer layer (160) are sequentially laminated on the entire surface of the substrate including the conductive thin film pattern (140). Accordingly, the light absorption layer (150) is also filled in the P1 region. Then, the buffer layer (160) and the light absorption layer (150) are scribed along the P2 region to expose the rear passivation layer (130).

[0090] In this state, a front transparent electrode (170) is laminated on the entire surface of the buffer layer (160). At this time, the front transparent electrode (170) is also filled in the P2 region. As the P2 region is filled with the front transparent electrode (170), the front transparent electrode (170) is electrically connected to the conductive thin film pattern (140) on the rear passivation layer (130). Here, the front transparent electrode (170) and the conductive thin film pattern (140) on the rear passivation layer (130) are each provided in an adjacent cell.

[0091] In a state where the front transparent electrode (170) is laminated, the front transparent electrode (170), buffer layer (160), and light absorption layer (150) are scribed along the P3 region to insulate the front transparent electrode (170) between neighboring cells.

[0092] Through the above process, a structure in which multiple double-sided light-receiving thin-film solar cell cells are integrated on one transparent substrate (110) can be completed.

[0093] In addition to the integration of the above-described double-sided light-receiving thin-film solar cell, light transmittance can also be additionally provided. After the above-described integration process is completed, as illustrated in FIG. 6, the front transparent electrode (170), the buffer layer (160), the light-absorbing layer (150), and the rear transparent electrode (120) are removed along the light-transmitting region (T), thereby exposing the transparent substrate (110). The area from which the front transparent electrode (170), the buffer layer (160), the light-absorbing layer (150), and the rear transparent electrode (120) are selectively removed corresponds to the light-transmitting region (T). The area of ​​the light-transmitting region (T) can be selectively adjusted, thereby controlling the light transmittance of the double-sided light-receiving thin-film solar cell. Here, the rear transparent electrode (120) may not be removed, and in this case, the rear transparent electrode (120) forms a structure in which it is exposed to the outside in the light-transmitting region (T).

[0094] Above, a double-sided light-receiving thin-film solar cell and its manufacturing method according to one embodiment of the present invention have been described. Below, the present invention will be described in more detail through experimental examples.

[0095] Experimental Example 1: TiO x Rear passivation characteristics depending on application

[0096] Indium tin oxide (ITO) was deposited on a soda-lime glass substrate by a sputtering process to a thickness of 600 nm, and then a TiO2 thin film was deposited. The thickness (t) of the TiO2 thin film was varied to 0, 1, 2, and 4 nm. A CIGS thin film was deposited on the TiO2 thin film by a three-stage simultaneous vacuum evaporation process at a substrate temperature of 450°C. Subsequently, a CdS thin film was deposited by a chemical bath deposition method, and i-ZnO and indium zinc oxide (IZO) thin films were deposited by sputtering, followed by deposition of a Ag metal electrode pattern to complete a CIGS thin-film solar cell.

[0097] The completed CIGS thin-film solar cell was irradiated with 1-sun light on the front and back, respectively, and the current-voltage characteristics were measured. Figure 7a shows the current-voltage characteristics according to front light incidence, and Figure 7b shows the current density-voltage (jV) characteristics according to back light incidence. Table 1 below summarizes the results of Figures 7a and 7b.

[0098] TiO2 thickness (nm) photocurrent characteristics back photocurrent ratio front back 0 3 2.9 7 5.6 7 0.1 7 2 1 32.6 8 6.4 6 0.1 9 8 2 32.5 1 1.5 2 0.3 5 4 4 32.7 3 1 1.8 0 3 6 1

[0099] <TiO2적용 여부 및 두께에 따른 전면 및 후면 광전류 특성>

[0100]

[0101] Referring to Fig. 7a, Fig. 7b and Table 1, the thin-film solar cell (TiO20 nm) without TiO2 applied has high resistance, which is believed to be due to the high resistance of the ITO / CIGS interface. In addition, the photocurrent was significantly reduced under back-light incidence conditions (photocurrent ratio 0.172), which is due to high charge recombination caused by defects at the ITO / CIGS interface. This result indicates that the passivation characteristic of the ITO / CIGS interface is poor. In the case of the thin-film solar cell with a 1 nm TiO2 thin film applied, there is no significant difference in the jV characteristics, and the level of improvement in back-light incidence (photocurrent ratio 0.198) is also minimal.

[0102] On the other hand, in the case of thin-film solar cells with 2 nm and 4 nm TiO2 thin films, the interfacial resistance is very high, so the FF (fill factor) is significantly low under front light incident conditions, but the photocurrent increases significantly under back light incident conditions (photocurrent ratio 0.354 to 0.361), indicating that the ITO / CIGS interface passivation characteristics are improved.

[0103] Experimental Example 2: Backside passivation and interface resistance characteristics according to application of Mo ultra-thin film

[0104] To overcome the high resistance at the ITO / CIGS interface, a 0.5 nm thick Mo layer was applied to the thin-film solar cell of Experimental Example 1. 0.5 nm Mo has a light absorption rate of less than 2%, allowing most light to pass through, and is expected to improve the interface resistance characteristics.

[0105] According to the jV results measured under front-side light-incident conditions (see Fig. 8a), Mo 0.5 nm can significantly reduce the interfacial resistance regardless of the TiO2 thickness. However, the series resistance slightly increased as the TiO2 thickness increased from 0 to 4 nm.

[0106] On the other hand, the jV results measured under back-illuminated conditions (see Fig. 8b) show that the interfacial passivation ability confirmed in the TiO2 thickness of 2 nm or more in Experimental Example 1 was lost in the cell structure with added Mo (0.5 nm).

[0107] These results can be expected to achieve both the effects of improving the back passivation characteristics by TiO2 and the interface resistance characteristics by Mo by introducing some areas of Mo.

[0108] Experimental Example 3: Ga precipitation characteristics

[0109] TEM and EDS analyses were performed on ITO / TiO2(4nm) / CIGS and ITO / TiO2(4nm) / Mo(0.5nm) / CIGS manufactured by Experimental Examples 1 and 2, respectively. Figures 9a and 9b show the TEM-EDS analysis results of ITO / TiO2(4nm) / CIGS manufactured by Experimental Example 1, and Figures 10a and 10b show the TEM-EDS analysis results of ITO / TiO2(4nm) / Mo(0.5nm) / CIGS manufactured by Experimental Example 2.

[0110] Referring to Figures 9a, 9b, 10a, and 10b, the oxygen of ITO and the Ga of CIGS react between the ITO layer and the CIGS layer to form GaO. xis formed. The TiO2 structure remains stable, but GaO x It appears to be ineffective in inhibiting the formation of GaO. This suggests that the presence of TiO2 has limitations in blocking oxygen diffusion. However, even when a Mo ultra-thin film layer is applied, GaO x The formation of TiO cannot be suppressed. x It is believed that oxygen passing through the / Mo layer reacts to form a GaOx layer. Consequently, each interface structure is ITO / TiO2 / GaO x / CIGS and ITO / TiO2 / Mo / GaO x / formed by CIGS. Both interfaces are GaO x / From the experimental fact that charge transfer of the second interface structure is easy while the back passivation performance is deteriorated despite containing the CIGS region, GaO x / CIGS interface is judged to have no significant function in terms of charge transfer or passivation performance. Therefore, it is TiO2 / GaO that determines the interfacial charge transfer and passivation performance. x This can be called an interface. The application of Mo forms additional surface defects at the interface, which facilitates recombination between p-type CIGS and n-type TiO2, thus facilitating charge transfer, but reducing passivation performance.

[0111] Experimental Example 4: TiO x Passivation and photocurrent characteristics according to oxygen content

[0112] TiO x The passivation characteristics and electrical characteristics according to the oxygen content were examined.

[0113] ITO / TiO according to Experimental Example 1 x / In manufacturing the CIGS structure, Nb-doped TiO x(Nb content: 10 wt%) TNO (titanium niobium oxide) was deposited by sputtering a sputtering target, and the flow rate of oxygen gas in the sputtering gas was adjusted to have an oxygen content (O2 / (Ar+O2)) of 0.08 to 0.5%. Then, the deposited TNO was subjected to rapid thermal annealing (RTA) at 350°C and 380°C (0.5% H2 atmosphere, vacuum degree 1 to 10 Torr for 30 minutes). Figure 11 shows the results of electrical resistivity characteristics according to the oxygen content of TNO (As-dep) that was not subjected to rapid thermal annealing and TNO that was subjected to rapid thermal annealing (RTA 350, RTA 380).

[0114] Referring to Fig. 11, in the state where rapid heat treatment is not performed (As-dep), the electrical resistivity is generally very high and shows a tendency to increase significantly as the oxygen content increases. After rapid heat treatment, crystallization occurs and the size of the electrical resistivity decreases by 2-4 orders of magnitude, and when the oxygen content is 0.1% or less, it decreases by 10 -3 It decreases to the level of Ωcm, but at oxygen contents above that, it decreases to 10 -1 It maintains a high electrical resistivity of ∼1 Ωcm. When the oxygen content is 0.3% or higher, it does not crystallize even after rapid heat treatment, resulting in a high resistivity comparable to that of an insulator. However, increasing the temperature (380°C) causes crystallization and a decrease in resistivity.

[0115] The front and rear photocurrent characteristics were investigated for thin-film solar cells using TNO with oxygen contents of 0.08% and 0.2%, respectively. Figures 12a and 12b show the experimental results of the front and rear photocurrent characteristics, respectively, and Table 2 below summarizes these results.

[0116] SampleTNOO2Eff[%]Voc[V]FF[%]Jsc[mA / cm 2]RatioFrontRearRef. S065105_B1014.50.70562.333.06.30.19S065106_B34nm0.2%6.00.57033.231.811.40.36S065107_A34nm0.08%11.20.68852. 332.16.80.21S065108_B14nm / RTA0.08%13.20.70257.332.96.50.20S065109_B31.5nm / RTA0.08%14.80.70164.632.77.00.21

[0117] <TNO가 적용된 박막태양전지의 전면 및 후면 광전류 특성>

[0118]

[0119] Referring to Figures 12a, 12b and Table 2, the higher the electrical resistivity of TNO, the larger the interfacial barrier that impedes charge transfer, resulting in a sharp decrease in FF of the solar cell, 1x10 4 Only TNO (O20.2%, not heat-treated, 4 nm thick) with the highest resistivity of Ωcm showed excellent rear passivation capability under rear light incidence. Next, after additionally applying a Mo thin film layer (0.5 nm) to the thin-film solar cell to which TNO with oxygen contents of 0.08% and 0.2% was applied, the front and rear photocurrent characteristics were examined. Figures 13a and 13b show the experimental results showing the front and rear photocurrent characteristics, respectively, and Table 3 below summarizes these results.

[0120] Referring to Figs. 13a and 13b and Table 3, regardless of the resistance of TNO, the addition of a Mo thin film layer significantly improved the interfacial charge transport ability, thereby presenting a similar or superior FF compared to the case without TNO. In addition, TNO also exhibits interfacial passivation ability when the electrical resistivity is increased, but loses the passivation ability when the electrical resistivity is decreased. Therefore, when a Mo thin film layer is applied, the interfacial passivation ability is significantly reduced, but the charge transport ability is improved, so that TNO can also be applied to a back passivation structure that introduces a Mo pattern, such as the structure of the present patent.

[0121] SampleTNOO2Efficiency[%]Voc [V]Jsc[mA / cm 2] FF[%]J-VRef. S065102_B3--15.20.69232.767.0S065103_B24nm0.2%15.70.70432.768.3S065104_A34nm0.08%16.00.70532.669.6

[0122] <TNO 및 Mo 박막층이 적용된 박막태양전지의 전면 및 후면 광전류 특성>

Claims

1. A rear transparent electrode laminated on a transparent substrate; A rear passivation layer laminated on a rear transparent electrode; A conductive thin film pattern formed on some area of ​​the rear passivation layer; A light absorbing layer laminated on the entire surface of a rear passivation layer including a conductive thin film pattern; A buffer layer laminated on a light absorbing layer; and A double-sided light-receiving thin-film solar cell characterized by comprising a front transparent electrode laminated on a buffer layer.

2. In the first paragraph, the rear passivation layer is TiO x or TaO x A double-sided light-receiving thin-film solar cell characterized by comprising:

3. In the second paragraph, TiO x A double-sided light-receiving thin-film solar cell characterized by an electrical resistivity of greater than 1 Ωcm.

4. In the first paragraph, the rear passivation layer is TiO doped with any one element of Nb, Sb, or S. x or TaO x A double-sided light-receiving thin-film solar cell characterized by comprising:

5. In the fourth paragraph, TiO doped with any one element of Nb, Sb, or S x A double-sided light-receiving thin-film solar cell characterized by an electrical resistivity of greater than 1 Ωcm.

6. In the first paragraph, the conductive thin film pattern is in the form of a dot or a line, A double-sided light-receiving thin-film solar cell characterized in that a plurality of conductive thin-film patterns are spaced apart and arranged on a rear passivation layer.

7. A double-sided light-receiving thin-film solar cell, characterized in that in clause 6, the total area of ​​a plurality of conductive thin-film patterns does not exceed 20% of the area of ​​the rear passivation layer.

8. In the 6th paragraph, if the conductive thin film pattern is in the form of a dot, The conductive thin film pattern has a length or diameter of 0.1 to 2 μm and a thickness of 0.1 to 2 nm. The distance between the conductive thin film patterns is the carrier diffusion length (L) in the light absorbing layer. D ) is equal to or smaller than that of a double-sided photovoltaic thin film solar cell.

9. In the 6th paragraph, if the conductive thin film pattern is linear, The width of the linear conductive thin film pattern is 0.1 to 2 μm, and its thickness is 0.1 to 2 nm. The distance between the conductive thin film patterns is the carrier diffusion length (L) in the light absorbing layer. D ) is equal to or smaller than that of a double-sided photovoltaic thin film solar cell.

10. A double-sided light-receiving thin-film solar cell, characterized in that in claim 1, the conductive thin film pattern is made of molybdenum (Mo).

11. A double-sided light-receiving thin-film solar cell, characterized in that in claim 1, the thickness of the rear passivation layer is 2 to 4 nm.

12. In the first paragraph, the light absorbing layer is CIGS (Cu (In 1-x , Ga x )(Se,S) 2 ) is characterized by a double-sided light-receiving thin-film solar cell.

13. In paragraph 1, the rear transparent electrode and the front transparent electrode are made of one of indium oxide, zinc oxide, and tin oxide. Indium oxide is InO x , ITO, (W, Ce, Mo)-doped InO x , IZO, and zinc oxide is (Al, Ga, B, Ti, F, H)-doped ZnO. x , and the tin oxide is (F, Sb)-doped SnO x A double-sided light-receiving thin-film solar cell characterized by:

14. In the first paragraph, a buffer layer is provided between the light absorbing layer and the front transparent electrode, A double-sided light-receiving thin-film solar cell characterized in that the buffer layer is made of one or a combination of CdS, InS(O,OH), ZnS(O,OH), ZnMgO, ZnTiO, and ZnSnO.

15. A double-sided light-receiving thin-film solar cell characterized in that, in claim 1, a light-transmitting region is provided in which a front transparent electrode, a light-absorbing layer, and a rear passivation layer of a specific region are removed to expose the rear transparent electrode.

16. A double-sided light-receiving thin-film solar cell characterized in that the light transmittance of the double-sided light-receiving thin-film solar cell can be controlled by adjusting the area of ​​the light-transmitting portion in the 15th paragraph.

17. In the first paragraph, a P1 region is provided in which a rear passivation layer and a rear transparent electrode are removed to a certain area, a P2 region is provided in which a buffer layer and a light absorption layer are removed to a certain area, and a P3 region is provided in which a front transparent electrode, a buffer layer, and a light absorption layer are removed to a certain area. A double-sided light-receiving thin-film solar cell characterized in that the back transparent electrode of a neighboring cell is insulated by the P1 region, the back transparent electrode and the front transparent electrode of the neighboring cell are connected by the P2 region, and the front transparent electrode of the neighboring cell is insulated by the P3 region.

18. A step of forming a rear transparent electrode on a transparent substrate; A step of sequentially laminating a rear passivation layer on a rear transparent electrode; A step of forming a conductive thin film pattern on a rear passivation layer; A step of forming a light absorption layer on the entire surface of a rear passivation layer including a conductive thin film pattern; and A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized by comprising the step of forming a front transparent electrode on a light-absorbing layer.

19. In the 18th paragraph, the step of forming a conductive thin film pattern on the rear passivation layer; A process of forming a mask that exposes a portion of the rear passivation layer on the rear passivation layer, A process of depositing a conductive metal on the entire surface of the rear passivation layer including the mask, A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized in that it comprises a process of forming a conductive thin-film pattern in a part of a rear passivation layer by removing a mask.

20. In the 18th paragraph, the rear passivation layer is TiO x or TaO x TiO composed of or doped with any one of the elements Nb, Sb, or S x or TaO x A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized by comprising:

21. A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized in that it further comprises a step of forming a light-transmitting region in which the rear transparent electrode is exposed by removing the front transparent electrode, the light-absorbing layer, and the rear passivation layer of a specific region in the 18th paragraph.

22. In clause 18, before forming the light absorbing layer, A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized by further comprising the step of scribing a rear transparent electrode and a rear passivation layer along a P1 region to a predetermined area to divide the cells into a plurality of cells and insulate the rear transparent electrodes between neighboring cells, while forming a conductive thin film pattern on a rear passivation layer.

23. In clause 18, after the formation of the light absorbing layer, A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized by further comprising the step of scribing a light-absorbing layer along a P2 region to expose a rear passivation layer.

24. In the 22nd paragraph, in a state where the front transparent electrode is laminated, A method for manufacturing a double-sided light-receiving thin-film solar cell, characterized by further comprising the step of scribing a front transparent electrode and a light-absorbing layer along a P3 region to insulate the front transparent electrode between neighboring cells.

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