TWM462952U - Structure of cigs-based solar cells using an anodized substrate with an alkali metal precursor - Google Patents

Abstract

A structure of CIGS-based solar cells using an anodized substrate with an alkali metal precursor is disclosed. The substrate includes a base layer; and an anodized layer with plural pores, wherein the plural pores are filled with an alkali metal precursor which will e extended to a chalcopyrite absorber layer while the chalcopyrite absorber layer is formed, and thereby providing and controlling the alkali metal precursor to the finished absorber layer with a desired content and preventing contamination from the substrate during the manufacturing process.

Description

Device structure of thin film solar cell

The present invention relates to a device structure applied to a thin film solar cell, and more particularly to an anode-treated substrate structure having a halogenated alkali metal precursor applied to a thin film solar cell.

With the global warming effect and the gradual consumption of fossil fuel resources, the development of emerging energy technologies has become a serious problem that human beings must face. Among many emerging energy sources, replacing traditional fossil fuel energy with solar cells is regarded as one of the effective ways to solve the problem. In addition to the inexhaustible advantages of solar cells, solar cells are a quiet, clean and pollution-free energy source that consumes little earth resources, and is easy to mine and process materials, plus long life of its power generation modules. The advantage has become the most important industry in the future. However, there are many types of solar cells in the market today. Generally speaking, single crystal germanium solar cells have high photoelectric conversion efficiency and long service life, but they are expensive, and are suitable for power plants or traffic lighting. usage of. As for another wide range of thin film solar cells, the materials which can be selected may be made of other materials such as cadmium telluride, indium gallium arsenide or gallium arsenide, in addition to amorphous germanium. Since the energy conversion efficiency of a thin film solar cell is critical to the material's energy gap, light absorption coefficient, and carrier transport characteristics, manufacturers must start with material selection and coating to produce a highly efficient solar cell.

In 1977, the University of Maine in the United States took the lead in researching copper indium and selenium. (copper indium selenide, referred to as CIS) three elements of materials to make thin-film solar cells, and later to improve conversion efficiency, the use of copper indium gallium selenium (CIGS) four-element material. Since the thickness of the photoelectric conversion layer of the CIGS thin film solar cell can be as thin as several micrometers, the material cost can be reduced, and the energy input during manufacturing can be saved. Once the photoelectric conversion layer is thinned, the light absorbing ability of the CIGS-based material also becomes quite high. In theory, the power generation efficiency of CIGS thin-film solar cells can be as high as 25~30%, which is much higher than single crystal germanium, and the average commercial CIGS module can reach 10~12%. On the other hand, CIGS-based semiconductors have the property of controlling the absorption wavelength field by changing the composition in the thickness direction. Therefore, if the composition is used to make the absorption wavelength field wider, the power generation efficiency of the solar cell can naturally be improved. Furthermore, CIGS thin-film solar cells have the advantage of being more difficult to degrade than samar-based solar cells under light or radiation, so the product has a longer life span and is more suitable for use in space. In addition, CIGS thin film solar cells are direct energy gap semiconductor materials with good light absorption characteristics, and their light absorption coefficient is superior to other solar cells. Based on the aforementioned excellent performance, CIGS thin film solar cells have become one of the focuses of the industry today.

Please refer to the first figure and the second figure at the same time, wherein the first figure is a schematic diagram of the structure of the CIGS thin film solar cell of the first prior art, and the second figure is a schematic diagram of the structure of the CIGS thin film solar cell of the second prior art. As shown in the first figure, the first conventional CIGS thin film solar cell has a structure mainly comprising a glass substrate 11, a back electrode 12, a CIGS absorption layer 13, a buffer layer 14, an intrinsic oxide layer 15, and a The transparent conductive film 16, an anti-reflection film 17, and an external electrode 18. Since the glass substrate 11 contains sodium (Sodium, Na) elements, sodium (Sodium, Na) elements diffuse into the CIGS absorption layer 13 during the co-evaporation process, thereby improving solar cell conversion efficiency and increasing the fill factor (Fill). Factor) and open-circuit voltage, improve CIGS conductivity and reduce CIGS Advantages such as grain size. However, in order to achieve the above advantages, the key is that the concentration of sodium must be controlled to an optimum value. If sodium is not incorporated, the solar cell efficiency will be reduced by 2% to 3%. Therefore, for some CIGS thin film solar cells of the second conventional technique without the sodium substrate 21 made of sodium-free polyimine (PI) or stainless steel, as shown in the second figure, except for the buffer layer 24 The structure of the intrinsic oxide layer 251, the transparent conductive film 252, the anti-reflection film 253, and the external electrode 254 is the same as that of the first conventional CIGS thin film solar cell, and it is also required to introduce the precursor layer sodium fluoride 26 on the back electrode 22. In order to supply the desired sodium concentration of the CIGS absorbing layer 23 to an optimum value. However, due to the sodium fluoride plated on the precursor layer of the polyimide or stainless steel substrate, after the CIGS thin film solar cell is fabricated, it must be completely consumed. Otherwise, the residual precursor sodium fluoride is easily formed between the CIGS absorber layer and the back electrode. The recombination center will greatly reduce the conversion efficiency of solar cells.

However, in practical applications, since the substrate used in the CIGS thin film solar cell needs to have flexibility, if a glass substrate is used, it is preferable to use a thin glass, but the thin glass material is too expensive and easily broken or caused in the process. Scratches and other missing. However, if a polyimide substrate is used, although it is flexible, it can withstand high temperatures up to about 300 ° C. However, subsequent processes, such as CIGS co-evaporation or sputtering processes, can reach temperatures as high as 300 ° C to 500 ° °C, will cause the polyimide substrate to warp and deform due to thermal stress, or debonding of the back electrode and the polyimide substrate, thereby reducing the yield, which is quite disadvantageous for the entire process. If a stainless steel substrate having a high flexibility is used, the insulation property is poor, and the reliability of the use tends to cause a serious problem of leakage current in the back electrode of the CIGS thin film solar cell.

U.S. Patent No. 5,626,688 proposes a diffusion barrier layer concept for the aforementioned problems. Please refer to the third figure, which is the third conventional skill. Schematic diagram of CIGS thin film solar cell structure. As shown in the third figure, the thin film solar cell structure has a glass substrate 31, a back electrode 32, a CIGS absorber layer 33, a buffer layer 34, an intrinsic oxide layer 351, a transparent conductive film 352, an antireflection film 353, and The external electrode 354 and the precursor layer sodium fluoride 36 equivalent to the second figure have a diffusion barrier layer 37 between the glass substrate 31 and the back electrode 32, which is made of an alumina material. Although the diffusion barrier layer can prevent the serious leakage current of the CIGS thin film solar cell using the stainless steel substrate, the stainless steel substrate does not contain sodium metal, and cannot provide and control the sodium content required for the CIGS thin film solar cell, which is not suitable for use. It is a substrate for CIGS thin film solar cells. If used in the sodium-containing glass substrate 31, the diffusion barrier layer 37 blocks the diffusion of sodium into the CIGS absorber layer 33, which affects the crystal growth and reduces the photoelectric conversion efficiency. However, the diffusion barrier layer 37 is grown on the glass substrate 31, and is generally achieved by magnetron sputtering. Therefore, the diffusion barrier layer 37 has limited quality and efficacy, and the manufacturing cost is relatively high. Unable to meet quality and cost considerations.

In short, the structure of the conventional CIGS thin film solar cell and its preparation method are limited by its structure and manufacturing process, such as the substrate used, whether it is a thin glass substrate or a polyimide (PI) substrate. Or the stainless steel substrate is missing, and at the same time there is the biggest problem that can not effectively control the optimal content of sodium ions introduced into the CIGS absorption layer, and it is also impossible to consider the production cost at the same time, which is worthy of research and improvement by the industry and scholars. In view of the lack of conventional skills, the applicant of this case, through careful testing and research, and a spirit of perseverance, proposed a "film cell structure for thin-film solar cells" by revealing the anode of a halogenated alkali metal precursor. The substrate structure and its processing flow can not only accurately control the content of the alkali metal introduced into the CIGS absorber layer, but also simplify the manufacturing process of the overall CIGS thin film solar cell, thereby reducing the production cost. .

This section summarizes some of the features of this creation, and other features will be described in subsequent paragraphs. This creation is defined by the scope of the appended patent application, which is hereby incorporated by reference.

The main purpose of the present invention is to provide an anode-treated substrate structure with a halogenated alkali metal precursor applied to a thin film solar cell. Through the introduction of the structure, the alkali metal diffusion content of the CIS/CIGS absorption layer can be effectively controlled by a simple pretreatment process. At the same time, the substrate may be prevented from being contaminated by the CIS/CIGS absorption layer in the overall process, thereby simplifying the overall process and reducing the production cost.

In order to achieve the above object, a preferred embodiment of the present invention provides a structural device for a thin film solar cell, the structure comprising at least a base layer, and an anodized layer formed on the base layer and having a plurality of An array of holes; wherein the plurality of holes further have a quantity of a halogenated alkali metal precursor for controlling the alkali metal diffusion content of the film. The anode treatment layer is an anodic aluminum oxide (AAO), and the plurality of aperture arrays are made of alumina having a hexagonal array structure, wherein the plurality of aperture arrays are The uniform straight channel has a hole diameter ranging from 14 nm to 300 nm, and the hole distribution has a density ranging from 10 ⁹ /cm ² to 10 ¹² /cm ² .

The case can be explained by the following figures and examples, and a clearer understanding is obtained.

11‧‧‧ glass substrate

12‧‧‧ Back electrode

13‧‧‧CIGS absorption layer

14‧‧‧buffer layer

15‧‧‧Nature oxide layer

16‧‧‧Transparent conductive film

17‧‧‧Anti-reflective film

18‧‧‧External electrode

21‧‧‧Sodium-free substrate

22‧‧‧ Back electrode

23‧‧‧CIGS absorption layer

24‧‧‧buffer layer

251‧‧‧Nature oxide layer

252‧‧‧Transparent conductive film

253‧‧‧Anti-reflective film

254‧‧‧External electrode

26‧‧‧ precursor layer sodium fluoride

31‧‧‧ glass substrate

32‧‧‧Back electrode

33‧‧‧CIGS absorption layer

34‧‧‧buffer layer

351‧‧‧Nature oxide layer

352‧‧‧Transparent conductive film

353‧‧‧Anti-reflective film

354‧‧‧External electrode

36‧‧‧ precursor layer sodium fluoride

37‧‧‧Diffusion barrier

40‧‧‧Substrate structure

401‧‧‧ basal layer

402‧‧‧Anode treatment layer

403‧‧‧ hole array

404‧‧‧ Halogenated alkali metal precursors

501‧‧‧ basal layer

502‧‧‧Aluminum layer

503‧‧‧ Sacrificial Alumina Layer

504‧‧‧Anode treatment layer

505‧‧‧ hole array

60‧‧‧Substrate structure

601‧‧‧ basal layer

602‧‧‧Anode treatment layer

603‧‧‧ hole array

604‧‧‧ Halogenated alkali metal precursors

61‧‧‧ Back electrode

62‧‧‧absorbing layer

63‧‧‧buffer layer

641‧‧‧Undoped zinc oxide layer

642‧‧‧Aluminum doped zinc oxide layer

643‧‧‧Magnesium fluoride layer

644‧‧‧Al-nickel alloy

First: It is a schematic diagram of the structure of a CIGS thin film solar cell of the first prior art.

Second: It is a schematic diagram of the structure of a CIGS thin film solar cell according to the second conventional technique.

The third figure is a schematic diagram of the structure of a CIGS thin film solar cell which is the third conventional technique.

FIG. 4 is a schematic view showing the structure of an anode-treated substrate with a halogenated alkali metal precursor applied to a thin film solar cell according to a preferred embodiment of the present invention.

Figure 5: It is a schematic diagram showing the manufacturing process of the anodized aluminum AAO structure in this case.

Figure 6 is a schematic view showing the structure of a CIGS thin film solar cell according to a preferred embodiment of the present invention.

Some exemplary embodiments embodying the features and advantages of the present invention are described in detail in the following description. It is to be understood that the present invention is capable of various modifications in the various aspects of the present invention, and the description and illustration are in the nature of

The present invention relates to an anode-treated substrate structure having a halogenated alkali metal precursor applied to a thin film solar cell and a method of manufacturing the same. It mainly adopts a base layer having porosity and heat resistance, and is introduced through a pretreatment device and a method, and in the subsequent process of forming a CIS/CIGS absorption layer, the quantitative halogenated alkali metal precursor pre-filled into the base layer is diffused. Up to the CIS/CIGS absorber layer, thereby providing and controlling the desired alkali metal content in the absorber layer; and effectively blocking possible sources of contamination from the substrate layer by the anodized layer on the substrate. The contents of the present invention will be further described in the following examples, but the structures and methods in which the present technology can be applied are not limited to the embodiments, and any other structures and methods applicable to the present technology can be incorporated herein by reference.

Please refer to the fourth figure, which discloses an anode-treated substrate structure of a halogenated alkali metal precursor applied to a thin film solar cell in a preferred embodiment of the present invention. As shown, the substrate structure 40 includes at least one base layer 401; and an anodized layer 402 formed on the base layer 401 and having a plurality of holes 403; wherein the plurality of holes 403 have a certain amount An alkali metal precursor 404 is halogenated to supply the alkali metal content of the absorbent layer. The anode treatment layer 402 is anodized aluminum, and the plurality of aperture arrays 403 are made of alumina having a hexagonal array of holes, wherein the plurality of aperture arrays 403 have uniform straight holes. The pore diameter may range from 14 nm to 300 nm, and the pore distribution may have a density ranging from 10 ⁹ /cm ² to 10 ¹² /cm ² . For the structure, the manufacturing method comprises at least the steps of: a) providing a substrate layer 401; b) anodizing the surface of the substrate layer 401 to form an anode treatment layer 402 having a plurality of aperture arrays 403; and c) The plurality of holes array 403 is filled with a halogenated alkali metal precursor 404. In practical applications, the structure can be fabricated by one-stage or two-stage anode treatment, and the filled alkali metal precursor 404 is a quantitative halogenated alkali metal precursor 404 to satisfy the thin film solar cell. The alkali metal content required for the CIS/CIGS absorber layer.

The fifth (A)-(E) further reveals the manufacturing flow chart of the anodized aluminum AAO structure of the present invention. First, a high-purity (99.9%) aluminum layer 502 is formed on a base layer 501, as shown in FIG. 5(A), wherein the aluminum layer 502 structure must have a vacuum degree of 10 ^-3 Pa before the subsequent process. Annealing was carried out at 550 ° C for 10 hours to remove internal residual stress and to obtain a homogeneous aluminum layer surface. Next, the aluminum layer 502 was plated with a DC voltage (42 V, 0 ° C) for 12 hours in a solution of 0.35 M oxalic acid (H ₂ C ₂ O ₄ ) to cause an electrochemical reaction on the surface of the aluminum layer 502. Further, a sacrificial aluminum oxide layer 503 is further formed on the surface of the aluminum layer 502, as shown in FIG. 5(B). Thereafter, the entire structure was immersed in a 65 ° C mixed solution of 6.5 wt.% phosphoric acid (H ₃ PO ₄ ) and 2.0 wt.% of chromic acid (H ₂ CrO ₄ ) for 122 hours to disengage the sacrificial alumina layer 503. The surface of the aluminum layer 502 is as shown in the fifth figure (C). Then, the same DC voltage (42 V, 0 ° C) as before is electroplated for 24 hours to obtain an anodized layer 504 as shown in Fig. 5 (D). The base layer 501 is an aluminum oxide layer, and the plurality of holes array 505 in the anodized layer 504 can be removed by a copper chloride solution having a concentration of 1.2 M, followed by a phosphoric acid solution having a concentration of 6 wt.% and a temperature of 23 ° C ( H ₃ PO ₄ ) is etched for 2 hours, and the anode treatment layer 504 and a portion of the aluminum layer 502 located at the bottom of each of the plurality of holes array 505 can be removed to slightly widen the width of each hole and obtain The anodized aluminum oxide (AAO) hole array structure shown in the fifth figure (E). As for the filling of the halogenated alkali metal precursor, it can be carried out in the form of an aqueous solution. Taking sodium fluoride (NaF) as an example, adding 4.13 g of sodium fluoride (NaF) at 25 ° C and 100 g of pure water can prepare the aqueous solution required for filling; if lithium fluoride (LiF) is used as an example, Then, the aqueous solution required for filling can be added to 2.7 g of lithium fluoride (LiF) at 20 ° C, 1 liter of pure water.

Of course, the anode-treated substrate structure of the halogenated alkali metal precursor in this case is not limited to the foregoing manufacturing method, and can be performed by a single-stage anode treatment. The method first forms an aluminum layer 502 on a substrate layer 501, as shown in FIG. 5(A), wherein the aluminum layer 502 structure must be decontaminated, etched in an alkaline solution, and etched before the subsequent process. The distilled water is washed and then electropolished to obtain the desired smooth surface structure. In the process of electrolytic polishing, the surface of the aluminum layer 502 must be immersed in a concentrated acid or alkali solution for several minutes to remove the oxide layer formed on the surface by electrolysis. At the same time, in order to maintain the surface cleanliness, the surface must be washed with distilled water and then stored in a nitrogen atmosphere. Next, the cleaned aluminum layer 502 is placed in a phosphoric acid solution, and a direct current voltage (100 V, 0 ° C, with a platinum sheet as a counter electrode) is introduced to cause an electrochemical reaction on the surface of the aluminum layer 502 to form on the surface of the aluminum layer 502. The anodized layer 504 is as shown in the fifth diagram (D). Finally, the entire structure is placed in a saturated solution of mercury chloride to remove residues in the plurality of holes 505. The bottom of the plurality of holes array 505 in the anodized layer 504 is first washed with distilled water and then immersed in a phosphoric acid solution having a concentration of 5 wt.% at 30 ° C for 30 minutes to obtain as shown in the fifth figure (E). Anodized aluminum oxide (AAO) hole array structure. The anodic aluminum oxide (AAO) pore array obtained according to the procedure has a pore diameter of 110±7 nm; and the pore density is about 10 ¹⁰ 10 10 ¹¹ /cm ² .

Please refer to the sixth figure, which is a schematic structural diagram of a CIGS thin film solar cell according to a preferred embodiment of the present invention. When the anode-treated substrate structure 60 having the halogenated alkali metal precursor 604 is applied to a thin film solar cell, the substrate structure 60 having the structure processed in advance according to the foregoing method includes a base layer 601 and an anode treatment having a plurality of holes array 603. The layer 602 and a halogenated alkali metal precursor 604 filled in the plurality of holes 603 further include a back electrode 61 formed on the anode treatment layer 602; an absorption layer 62 is formed on the back electrode 61, and The alkali metal of the halogenated alkali metal precursor may be diffused therein; a buffer layer 63 is formed on the absorption layer 62 as shown in FIG. In practical applications, the aforementioned halogenated alkali metal precursor 604 is selected from one of sodium fluoride (NaF), lithium fluoride (LiF), sodium sulfide (Na ₂ S) or sodium selenide (Na ₂ Se). On the anode treatment layer 602 of the 150 micron substrate structure 60, the back electrode 61 can be sputtered with molybdenum metal by DC magnetron sputtering of 2 kW, and the substrate temperature is controlled at 300 ° C to form A back electrode 61 having a thickness of about 500 nm and having a two-layer molybdenum structure. The absorbing layer 62 can be formed by a multi-source simultaneous vapor deposition method using four elements of copper indium gallium selenide (CIGS). If it is subdivided into a three-stage evaporation process, indium, gallium and selenium are first vapor deposited on the back electrode 61 at 400 ° C to form a 2 μm (indium, gallium) 2 selenium 3 compound layer; then copper and selenium The element is added directly to the (indium, gallium) 2 selenide 3 compound layer to form a copper-rich CIGS layer at a temperature of 560 ° C; and the third stage of indium, gallium and selenium elements are further evaporated on the CIGS layer, so that It is transformed into a CIGS composition rich in (indium, gallium). However, the absorbent layer 62 produced in accordance with the foregoing process has an overall thickness of about 25 microns. On the absorbing layer 62, a cadmium sulfide (CdS) or zinc sulfide (ZnS) material is further deposited by a chemical bath deposition (CBD) and RF magnetron sputtering. The buffer layer 63 is formed to have a thickness of about 50 nm. Then, the buffer layer 63 can be composed of a plurality of combinations to form a multi-layer transparent electrode structure, if a 70 nm undoped zinc oxide layer/400 nm aluminum doped zinc oxide layer/100 nm magnesium fluoride layer/2 For example, the light-transmissive electrode structure of the micro-aluminum-nickel alloy can be firstly deposited on the buffer layer 63 by RF magnetron sputtering, and then deposited by RF magnetron sputtering. A zinc oxide layer 642 is deposited on the undoped zinc oxide layer 641; then a magnesium fluoride layer 643 is deposited on the aluminum-doped zinc oxide layer 642 by DC sputtering; finally, by thermal evaporation. A thermal nickel is deposited on the magnesium fluoride layer 643 to form an intrinsic oxide layer, a transparent conductive film, an antireflection film, and an external electrode structure, respectively. Therefore, the thin film solar cell structure disclosed in the present invention can increase the open circuit voltage (the maximum voltage output when the open-circuit voltage is infinite) to 689 mV on the 16 square centimeter operating region, and the short circuit current (the load is zero). The maximum current output is 30 mA/cm ² , which makes the conversion efficiency reach 14.5%, and the fill factor for judging its quality is increased to 67%, indicating the structure of the thin film solar cell and its structure. The preparation method is practical and excellent.

Of course, in the embodiment included in the technology of the present invention, the base layer which the thin film solar cell can employ is not limited to the aluminum or alumina material of the above-mentioned exemplary embodiment, and other porous heat resistant substrates having similar properties, such as titanium alloy. Materials or ceramic materials are also included in the technical scope of this case.

In summary, the present invention provides an anode-treated substrate structure with a halogenated alkali metal precursor applied to a thin film solar cell and a preparation method thereof. The introduction of the device structure and method of the present invention can form a CIS/CIGS absorption layer subsequently. During the process, a quantitative halogenated alkali metal precursor pre-filled into the substrate layer is diffused to the CIS/CIGS absorber layer to simultaneously satisfy the alkali metal content required for the CIS/CIGS absorber layer, and is effective by the anode treatment layer on the substrate. Blocking possible sources of contamination from the substrate layer is an important effect that is not possible with conventional techniques. The technology of this case is practical, novel and progressive, and it is submitted in accordance with the law. Even though the present invention has been described in detail by the above-described embodiments, it can be modified by those skilled in the art, and is not intended to be protected by the appended claims.

60‧‧‧Substrate structure

601‧‧‧ basal layer

602‧‧‧Anode treatment layer

603‧‧‧ hole array

604‧‧‧ Halogenated alkali metal precursors

61‧‧‧ Back electrode

62‧‧‧absorbing layer

63‧‧‧buffer layer

641‧‧‧Undoped zinc oxide layer

642‧‧‧Aluminum doped zinc oxide layer

643‧‧‧Magnesium fluoride layer

644‧‧‧Al-nickel alloy

Claims (12)

A structural device for a thin film solar cell, the structure comprising at least: a base layer; and an anodized layer formed on the base layer and having a plurality of arrays of holes; wherein the plurality of holes further have a halogenated base A metal precursor used to control the alkali metal diffusion content of the film. The structural device of claim 1, wherein the anodized layer is an anodic aluminum oxide (AAO), and the plurality of holes array is a hexagonal hole array The structure of alumina is composed. The structural device of claim 2, wherein the plurality of arrays of holes have uniform straight holes, the diameter of the holes ranges from 14 nm to 300 nm, and the density of the holes ranges from 10 ⁹ /cm ² to 10 ¹² /cm ² . The structure of the application device according to item 1 of the scope of the patent, wherein the alkali metal halide precursor is selected from sodium fluoride (NaF), lithium fluoride (of LiF), sodium sulfide (Na ₂ S) or sodium selenide (Na _{One of 2} Se). The structural device of claim 1, wherein the substrate layer is a porous heat-resistant substrate layer. The structural device according to claim 1, wherein the base layer is made of aluminum or aluminum oxide. The structural device of claim 1, wherein the base layer is made of titanium Made of alloy or ceramic material. The structural device of claim 1, further comprising: a back electrode formed on the anodized layer; an absorbing layer formed on the back electrode; a buffer layer formed on the absorbing layer; And a transparent electrode formed on the buffer layer; wherein, when the back electrode and the absorption layer are formed, the alkali metal of the halogenated alkali metal precursor diffuses into the absorption layer, thereby supplying the alkali in the absorption layer Metal content. The structural device of claim 8, wherein the halogenated alkali metal precursor is a quantity of an alkali metal halide precursor to supply an alkali metal content required for the absorption layer. The structural device of claim 8, wherein the back electrode is a two-layer molybdenum structure formed by sputtering molybdenum metal. The structural device according to claim 8, wherein the absorbing layer is composed of a copper indium selenide (CIS) three element or a copper indium gallium selenide (CIGS) Elemental composition. The structural device according to claim 8, wherein the buffer layer is made of cadmium sulfide (CdS) or zinc sulfide (ZnS).