KR101012847B1 - manufacturing method of compound sollar cell using ??? nanorod and the compound sollar cell - Google Patents

Abstract

The present invention relates to a compound solar cell, comprising: a first step of forming a window layer on an upper glass layer; Forming a ZnO nanorod layer on the window layer; Forming a buffer layer along the ZnO nanorods of the ZnO nanorod layer; Forming a light absorption layer on the buffer layer; A fifth step of forming an electrode layer on the light absorption layer; A method of manufacturing a compound solar cell using a ZnO nanorod, and a compound solar cell using the ZnO nanorod according to the manufacturing method, comprising a sixth step of forming a substrate on the electrode layer. . Accordingly, the ZnO nanorod layer is formed between the light absorption layer and the window layer with the buffer layer interposed therebetween, thereby increasing the electron diffusion coefficient and improving the electrical and optical properties of the solar cell, thereby increasing the efficiency of the solar cell. By controlling the size of the nanorod, there is an effect that can easily control the efficiency of the solar cell, and also, by plasma treatment of the window layer or ZnO nanorod layer, the window layer and the ZnO nanorod layer, and the ZnO By improving the adhesion between the nano-bar layer and the buffer layer, there is an advantage that the performance of the solar cell lasts long.

Compound Solar Cell ZnO Nanorod Flexible Plasma

Description

Manufacturing method of compound sollar cell using photon nanorod and the compound sollar cell}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound solar cell. In particular, a ZnO nanorod layer is formed between a light absorption layer and a window layer with a buffer layer interposed therebetween, thereby increasing the electron diffusion coefficient and improving the electrical and optical characteristics of the solar cell. The present invention relates to a method for manufacturing a compound solar cell using a ZnO nanorod for improving performance and a compound solar cell thereby.

Recently, with the depletion of natural resources, environmental and stability issues for thermal and nuclear power generation, research on environmentally friendly energy is being actively conducted. In such environmentally friendly power generation system, solar energy is attracting attention as an important alternative energy.

This solar energy is an endless and permanent energy source that is not depleted. It is free from environmental pollution, there is no risk of explosion, and it is stable. It can be installed regardless of size or region, and maintenance costs are low. It can be applied to various fields such as module, manufacturing equipment and installation.

In particular, the present invention will look for a solar cell using the solar energy. Generally, solar cells are divided into crystalline silicon solar cells, compound solar cells, stacked solar cells, and the like.

The crystalline silicon solar cell is limited to reduce the production cost due to the substrate of about 200㎛, in particular, the supply instability of the silicon raw material is also pointed out as a problem.

Therefore, research on thin film solar cells is active with compound solar cells that use low-cost substrates such as glass instead of crystalline silicon solar cells and can manufacture solar cells with only a thin layer of about 5 μm. In particular, CIGS thin film solar cells In the case of low production cost has been the most active research in recent years.

The CIGS solar cell has a high light absorption coefficient and is chemically stable, which is high in efficiency and stable compared to other thin film solar cells, and its efficiency is similar to that of crystalline silicon solar cells. The large area modules show 11% to 13% efficiency, which is higher than silicon thin films and CdTe solar cells.

As shown in FIG. 1, the structure of the CIGS solar cell includes a substrate 10, a back electrode 20, a light absorption layer 30, a buffer layer 40, a window layer 50, and the like.

In general, a glass substrate 10 is used as the substrate 10, and a metal such as Mo is used as the back electrode 20, and the CIGS and the buffer layer 40 mentioned above are used as the light absorption layer 30. ZnS is used, and as the window layer 50, research on AZO and i-ZnS is most active.

In particular, the solar cell of the above structure has come by a method of controlling the thickness of the thin film or doping impurities in AZO or the like in order to control the efficiency of the solar cell according to the purpose or use. However, such a method is not very easy, and accurate efficiency cannot be predicted, resulting in waste of energy.

In addition, it is necessary to further increase the efficiency of the solar cell in order to apply the commercialization, it is necessary to improve the adhesion between each material to maintain the performance of the solar cell.

The present invention is to solve the above problems, by forming a ZnO nano-rod layer between the light absorbing layer and the window layer with a buffer layer, thereby increasing the electron diffusion coefficient to improve the electrical and optical characteristics of the solar cell, It is an object of the present invention to provide a method for producing a compound solar cell using a ZnO nanorod for improving performance and a compound solar cell thereby.

The present invention to achieve the above object, the first step of forming a window layer on the glass upper layer; Forming a ZnO nanorod layer on the window layer; Forming a buffer layer along the ZnO nanorods of the ZnO nanorod layer; Forming a light absorption layer on the buffer layer; A fifth step of forming an electrode layer on the light absorption layer; A method of manufacturing a compound solar cell using a ZnO nanorod, and a compound solar cell using the ZnO nanorod according to the manufacturing method, comprising a sixth step of forming a substrate on the electrode layer. .

Here, after the sixth step, the step of removing the glass of the first step is further added according to the use of the solar cell.

The window layer may be any one of a ZnO thin film layer, an AZO thin film layer in which Al or B is doped with ZnO, and a BZO thin film layer. The window layer may be RF sputtering or reactive sputtering. (reactive sputtering) and MOCVD (Metal Organic Chemical Vapor Deposition) is preferably formed by any one of the methods. In addition, it is preferable that a plasma treatment process of the window layer is further performed after the formation of the window layer.

In addition, the ZnO nanorod layer is preferably formed using a tube furnace, and after the formation of the ZnO nanorod layer, it is preferable that a plasma treatment step of the ZnO nanorod layer is further performed.

In addition, the buffer layer is preferably any one of ZnS, CdS, ZnSe, InS, InOOH, and ZnOOH, and the buffer layer is preferably formed by a chemical bath deposition (CBD) method or an RF spattering method. .

The light absorbing layer is preferably CIS or CIGS, and the light absorbing layer is preferably formed by an evaporation method, an RF sputtering method, or an electrodeposition method.

Moreover, it is preferable to use any one of Mo, Ni, Au, Al, and Cu as the said electrode layer, and it is preferable that the said electrode layer is formed by the DC spattering method.

In addition, the substrate may be formed by bonding any one of glass, a copper plate, a copper tape, a ceramic substrate, and a SUS plate on the electrode layer, or the polymer. It is preferable to form a coating on the upper electrode layer.

According to the above problem solving means, the present invention provides a ZnO nanorod layer between the light absorption layer and the window layer with the buffer layer interposed therebetween, thereby increasing the electron diffusion coefficient and improving the electrical and optical characteristics of the solar cell. It is possible to further increase, and by adjusting the size of the ZnO nano-rod, there is an effect that can easily control the efficiency of the solar cell.

In addition, plasma treatment of the window layer or the ZnO nanorod layer improves the adhesion between the window layer and the ZnO nanorod layer, and the ZnO nanorod layer and the buffer layer, thereby maintaining the performance of the solar cell for a long time. .

The present invention is formed on the light absorption layer using the ZnO nano-rod to improve the performance and efficiency of the solar cell, to form a window layer on the upper glass layer, the ZnO nano-rod layer with a buffer layer between the light absorption layer and the window layer To form an electrode layer and a final substrate to produce a compound solar cell.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

2 and 3 show an embodiment of the present invention according to the substrate, the upper portion of the figure absorbs sunlight. As shown, the compound semiconductor using the ZnO nanorod according to the present invention, the glass 100, the window layer 200, the ZnO nanorod layer 300, the light absorption layer 500, the electrode layer 600 and the substrate ( 700).

Since sunlight is incident on the window layer 200 through the glass 100, the glass 100 is formed of a transparent material having a high transmittance of sunlight, and the glass 100 is incident on the solar cell. An anti-reflection film MgF ₂ is formed to minimize reflection loss of sunlight.

In some cases, by removing the glass 100 in the final step of the solar cell manufacturing process, the glass 100 may absorb all the UV light blocked by the glass 100, thereby increasing the absorption rate of the solar light. It is also more preferable that the glass 100 is removed when the flexible substrate 700 is used.

In addition, a window layer 200 is formed on the glass 100, and the window layer 200 is generally a CIS or CIGS used as a light absorption layer 500 to be described later as an n-type semiconductor in a compound solar cell. And a pn junction, and the window layer 200 functions as a transparent electrode in front of the solar cell, so the light transmittance should be high and the electrical conductivity should be good.

The material used for the window layer 200 may be any one of ZnO, AZO and BZO doped with Al or B in the ZnO. The ZnO has an energy band gap of about 3.3 eV and a high light transmittance of about 80% or more. In addition, a low resistance value of 10 ⁻⁴ Ωcm or less can be obtained by doping with Al, B, or the like. It is also doped with B, the light transmittance in the near infrared region is increased to increase the short-circuit current, it is preferable to use AZO or BZO depending on the application. The window layer 200 is deposited using a ZnO target by RF sputtering, reactive sputtering using Zn metal, and a metal organic chemical vapor deposition (MOCVD) method. Etc. are currently used.

Either using a double structure in which an indium tin oxide (ITO) thin film having excellent electro-optic properties is deposited on a ZnO thin film, or an undoped i-type ZnO thin film is first deposited on a CdS thin film, and then a low resistance n-type thin film is deposited thereon. A method of depositing and using a ZnO thin film is also known.

Plasma treatment of the window layer 200 deposited after the formation of the window layer 200 improves the electrical and optical characteristics to improve the efficiency of the solar cell, and also the adhesion force with the ZnO nanorod layer 300 to be described later. Excellent to maintain the performance of the solar cell.

Next, the ZnO nanorod layer 300 is formed inside the light absorption layer 500 on the window layer 200, thereby improving the efficiency of the solar cell.

Since the ZnO nanorods 300 are all single crystals of the ZnO nanorods, the electron diffusion coefficient is much higher than that of a general ZnO thin film layer or bulk, which is excellent in electrical and optical characteristics. The ZnO nanorods may be prepared by using a vapor-liquid-solid (VLS) method using a catalyst, a VS method without a catalyst, plasma-enhanced chemical vapor deposition (PECVD), pulsed laser deposition (PLD), and metalorganic vapor phase (MOVPE). epitaxy, etc., in which deposition is performed at a low temperature of 500-600 ° C. using a tube furnace without using a catalyst.

In addition, after the ZnO nanorod layer 300 is formed, plasma treatment is performed separately to further improve electrical and optical properties, and surface adhesion is increased to improve adhesion to the buffer layer 400 to be described later. Long lasting performance.

In addition, the density and size (diameter, length) of the ZnO nanorods can be controlled to easily control the efficiency of the solar cell.

Next, the buffer layer 400 is formed along the ZnO nanorod of the ZnO nanorod layer 300, the compound solar cell according to the present invention is a light absorption layer 500 to be described later as a p-type semiconductor Cu (In, Since the ZnO (or AZO, BZO) thin film used as the Ga) Se ₂ thin film and the window layer 200 which is an n-type semiconductor forms a pn junction, the difference in lattice constant and energy band gap between the two materials is reduced. Due to its size, a buffer layer 400 is required in which a band gap is located between two materials to form a good junction.

As the buffer layer 400, any one of ZnS, CdS, ZnSe, InS, InOOH, and ZnOOH is used, and the buffer layer 400 is formed by a chemical bath deposition (CBD) method or an RF spattering method.

Next, the light absorption layer 500 uses CIS (CuInSe ₂ ) or CIGS (Cu (In _x Ga _{1 -x} ) Se ₂ ). CuInSe ₂ , a ternary compound, has an energy band gap of 1.04 eV and has a short circuit current, but has a disadvantage in that high efficiency cannot be obtained due to a low open voltage. In order to increase the open voltage, a portion of In of CuInSe ₂ is replaced with Ga element. Or replace Se with S.

CuGaSe ₂ has a bandgap of 1.5 eV, and the band gap of the Cu (In _x Ga _{1- x} ) Se ₂ compound semiconductor to which Ga is added can be adjusted according to the amount of Ga added. However, when the energy band gap of the light absorption layer 500 is large, the open circuit voltage is increased. However, since the short circuit current is reduced, proper content control of Ga is required.

As such, since the CIS thin film is a multi-element compound, the manufacturing process is very difficult. Physical thin film manufacturing methods include evaporation, selenization and sputtering methods, and chemical methods, such as electrodeposition, and starting materials (metals, binary elements). Various preparation methods can be mobilized depending on the kind of the compound). The best efficiency to date has been achieved by using the four metal elements—Cu, In, Ga, Se— as the starting material in the evaporation method. Since the characteristics of the CIS or CIGS thin film are greatly changed not only by the composition of the thin film but also by the temperature and deposition time of the substrate 700, strict process control is essential to maintain the deposition uniformity.

Next, the electrode layer 600 may be used for all metals used as electrodes, and in particular, any one of Mo, Ni, Au, Al, and Cu may be used, and high electrical conductivity and ohmic contact with CIGS may be used. (ohmic contact), Mo is more preferable to use Mo because of the high temperature stability under Se atmosphere. The Mo electrode layer 600 should have a low resistivity as an electrode and excellent adhesion to the substrate 700 so that peeling does not occur due to a difference in thermal expansion coefficient.

In addition, the substrate 700 bonds one of glass, a copper plate, a copper tape, a ceramic substrate 700, and a sustain plate to the electrode layer 600. Or by coating a polymer on the upper layer of the electrode layer 600. According to the flexibility of the substrate 700, a flexible solar cell can be manufactured, thereby increasing the utilization of the solar cell.

In the solar cell manufactured in the order of the components, the glass 100 formed under the window layer 200 may be removed. This is to remove all the UV light blocked by the glass 100 by removing in the final step of the solar cell manufacturing process, it is also possible to increase the absorption rate of sunlight. It is also more preferable that the glass 100 is removed when the flexible substrate 700 is used.

In the compound solar cell according to the present invention configured as described above, the ZnO nanorod layer 300 is formed between the light absorption layer 500 and the window layer 200 with the buffer layer 400 therebetween, thereby increasing the electron diffusion coefficient. By improving the electrical and optical characteristics of the solar cell, to provide a high efficiency solar cell.

In addition, the window layer 200 or the ZnO nanorod layer 300 may be plasma-processed to provide the window layer 200, the ZnO nanorod layer 300, and the ZnO nanorod layer 300 and the buffer layer 400. Improved adhesion to the solar cell, so that the performance of the solar cell is long lasting.

1-Schematic diagram of a conventional compound solar cell.

Figure 2, Figure 3-schematic diagram showing an embodiment of the present invention according to the substrate.

<Description of Major Symbols Used in Drawings>

100: glass 200: window layer

300: ZnO nano bar layer 400: buffer layer

500: light absorption layer 600: electrode layer

700: Substrate

Claims (24)

A ZnO thin film layer formed on the glass 100, a AZO thin film layer doped with Al or B on the ZnO, and a window layer 200 formed of any one of the BZO thin film layer, and the plasma processing process is performed on the window layer 200 Step 1; Forming a ZnO nano-rod layer 300 on the plasma-treated window layer 200; A third step of forming a buffer layer 400 along the ZnO nanorods of the ZnO nanorod layer 300; A fourth step of forming a light absorption layer 500 on the buffer layer 400; A fifth step of forming an electrode layer 600 on the light absorbing layer 500; And a sixth step of forming a substrate (700) on the electrode layer (600). The method of manufacturing a compound solar cell using a ZnO nanorod, characterized in that it comprises a. delete The method of claim 1, wherein the window layer 200, A compound solar cell using ZnO nanorods, which is formed by any one of RF sputtering, reactive sputtering, and metal organic chemical vapor deposition (MOCVD). Manufacturing method. delete According to claim 1, The ZnO nano-rod layer 300, Method for producing a compound solar cell using a ZnO nanorods, characterized in that formed using a tube furnace. According to claim 5, After the formation of the ZnO nano-rod layer 300, Method for manufacturing a compound solar cell using the ZnO nano-rod, characterized in that the plasma processing step of the ZnO nano-rod layer (300) is further made. The method of claim 1, wherein the buffer layer 400, ZnS, CdS, ZnSe, InS, InOOH and ZnOOH any one of the manufacturing method of a compound solar cell using a ZnO nano-rod, characterized in that. The method of claim 7, wherein the buffer layer 400, A method of manufacturing a compound solar cell using a ZnO nanorod, characterized in that formed by a chemical bath deposition (CBD) method or an RF spattering method. The method of claim 1, wherein the light absorption layer 500, Method for producing a compound solar cell using a ZnO nano-rod, characterized in that the CIS or CIGS. 10. The method of claim 9, wherein the light absorption layer 500, A method of manufacturing a compound solar cell using a ZnO nanorod, characterized in that formed by evaporation, RF sputtering, electrodeposition. The method of claim 1, wherein the electrode layer 600, Method for producing a compound solar cell using a ZnO nanorod, characterized in that any one of Mo, Ni, Au, Al and Cu. The method of claim 11, wherein the electrode layer 600, A method for producing a compound solar cell using a ZnO nanorod, characterized in that formed by the DC spattering method. The method of claim 1, wherein the substrate 700, Glass, copper plate (Cu plate), copper tape (Cu tape), the ceramic substrate 700 and the sustain plate (SUS plate) is formed by bonding any one of the upper electrode layer 600, or the polymer Method of manufacturing a compound solar cell using a ZnO nano-rod characterized in that the coating is formed on the upper electrode layer (600). The ZnO according to any one of claims 1, 3 and 5 to 13, further comprising a step of removing the glass 100 of the first step after the sixth step. Method for producing a compound solar cell using a nano-rod. delete Glass 100; A window layer 200 formed on the glass 100 and plasma-treated; A ZnO nanorod layer 300 formed on the window layer 200; A buffer layer 400 formed along the ZnO nanorods of the ZnO nanorod layer 300; A light absorption layer 500 formed on the buffer layer 400; An electrode layer 600 formed on the light absorption layer 500; Compound solar cell using a ZnO nano-rod characterized in that it comprises a; substrate 700 formed on the electrode layer (600). The method of claim 16, wherein the window layer 200, A ZnO thin film layer, a compound solar cell using a ZnO nanorods, characterized in that any one of the ZnO doped Al or B doped AZO thin film layer and BZO thin film layer. delete The compound solar cell of claim 16, wherein the ZnO nanorod layer (300) is plasma treated. The method of claim 16, wherein the buffer layer 400, A compound solar cell using a ZnO nanorod, wherein any one of ZnS, CdS, ZnSe, InS, InOOH, and ZnOOH is used. The method of claim 16, wherein the light absorption layer 500, Compound solar cell using ZnO nanorods, characterized in that the CIS or CIGS. The method of claim 16, wherein the electrode layer 600, Compound solar cell using a ZnO nano-rod, characterized in that any one of Mo, Ni, Au, Al and Cu. The method of claim 16, wherein the substrate 700, It is formed by bonding any one of glass, a copper plate (Cu plate) and a sus plate (SUS plate) on the upper electrode layer 600, or is formed by coating a polymer on the upper layer of the electrode layer 600 Compound solar cell using ZnO nanorods. delete

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