Disclosure of Invention
Based on the above, there is a need to provide a method and an apparatus for manufacturing a solar cell, which are directed to the problems of loss of incident light, difficulty in integrating a light trapping structure into the existing roll-to-roll flexible thin film cell manufacturing process, and relatively high cost in the solar cell.
The application provides a preparation method of a solar cell, which comprises the following steps:
s100, providing a flexible substrate;
s200, preparing a back electrode layer on the surface of the flexible substrate;
s300, preparing an absorption layer on the surface of the back electrode layer away from the flexible substrate;
s400, preparing a buffer layer on the surface of the absorption layer far away from the back electrode layer;
s500, preparing a high-resistance layer on the surface of the buffer layer far away from the absorption layer;
s600, preparing a window layer on the surface, far away from the buffer layer, of the high-resistance layer, wherein the window layer comprises an indium tin oxide layer and an aluminum-doped zinc oxide layer arranged on the surface, far away from the high-resistance layer, of the indium tin oxide layer;
s700, etching the aluminum-doped zinc oxide layer by using wet etching to form light trapping structures arranged at intervals.
In one embodiment, in S700, the PH of the etching solution for wet etching is less than 7.
In one embodiment, in S700, the wet etching temperature is 20 ℃ to 30 ℃.
In one embodiment, in S700, the etching time of the wet etching is 1min to 30 min.
In one embodiment, the flexible substrate is a stainless steel, aluminum alloy, molybdenum, titanium metal coil.
In one embodiment, the S200 includes:
s210, cleaning the flexible substrate by ultrasonic cleaning;
s220, preparing a back electrode layer on the surface of the cleaned flexible substrate.
In one embodiment, an apparatus for manufacturing a light trapping structure includes:
the conveying structure is used for flatly conveying the solar cells arranged on the surface of the conveying structure;
the liquid storage tank is internally stored with etching liquid so as to carry out wet etching on the reaction tank for carrying out wet etching on the surface of the solar cell conveyed by the conveying structure;
and the circulating structure is arranged in the liquid storage tank and used for keeping the uniformity of the temperature of the solution in the liquid storage tank. In one embodiment, a temperature control device is arranged in the liquid storage tank.
In one embodiment, the conveying structure comprises:
the winding drums are arranged at the head end and the tail end of the solar cell conveying line and are used for winding the solar cells into a coil;
and the guide roller is arranged on the solar cell conveying route and used for guiding the conveying direction of the solar cell.
In one embodiment, the manufacturing apparatus of the light trapping structure further includes rollers disposed on two sides of the guide roller to keep the solar cell flat and uniform in pressure.
In the preparation method and the preparation device of the solar cell provided by the application, the back electrode layer, the absorption layer, the buffer layer, the high resistance layer and the window layer are sequentially arranged on the surface of the flexible substrate. Because the window layer comprises the indium tin oxide layer and the aluminum-doped zinc oxide layer. Thus, the window layer not only has high light transmittance and high conductivity of the indium tin oxide layer. In addition, the aluminum-doped zinc oxide layer can be etched by a wet method to prepare the light trapping structures arranged at intervals. Therefore, the reflection of surface incident light can be reduced, the light absorption of the cell is enhanced, the short-circuit current of the solar cell is improved, the open-circuit voltage and the filling factor of the cell are not reduced, and the conversion efficiency of the cell is improved. In addition, the wet etching preparation of the light trapping structure is simple in process, free of vacuum environment and low in cost, and can be directly integrated into the existing production line to realize online continuous production.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clearly understood, the following description will be made in detail by way of examples, with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1 and 2, the present application provides a method for manufacturing a solar cell, including:
s100, providing a flexible substrate 10;
s200, preparing a back electrode layer 20 on the surface of the flexible substrate 10;
s300, preparing an absorption layer 30 on the surface of the back electrode layer 20 far away from the flexible substrate 10;
s400, preparing a buffer layer 40 on the surface of the absorption layer 30 far away from the back electrode layer 20;
s500, preparing a high-resistance layer 50 on the surface of the buffer layer 40 away from the absorption layer 30;
s600, preparing a window layer 60 on the surface of the high-resistance layer 50 far away from the buffer layer 40, wherein the window layer 60 comprises an indium tin oxide layer 61 and an aluminum-doped zinc oxide layer 62 arranged on the surface of the indium tin oxide layer 61 far away from the high-resistance layer 50;
s700, etching the aluminum-doped zinc oxide layer 62 by using wet etching to form light trapping structures 63 arranged at intervals.
In S100, the material of the flexible substrate 10 is not limited, and may be a polymer (e.g., polyimide), stainless steel. The thickness of the flexible substrate 10 is also not limited. The flexible substrate 10 functions as a carrier. The flexible substrate 10 should be cleaned before further coating. The flexible substrate 10 should be continuously transferred into an ultrasonic capable cleaning machine and after ultrasonic washing in heated cleaning machine solution followed by ultrasonic rinsing in deionized water and drying, the cleaned flexible substrate 10 will be moved to the next production step.
In S200, depositing the back electrode layer 20 on the surface of the flexible substrate 10 by a magnetron sputtering method. The material of the back electrode layer 20 may be one of metal molybdenum, titanium, chromium, copper, or transparent conductive layer aluminum-doped zinc oxide, boron-doped zinc oxide, and indium tin oxide, and is preferably molybdenum. The loose structure of molybdenum can improve the adhesion of the back contact layer and the flexible substrate 10. In addition, the resistivity of the low-resistance molybdenum metal layer is small, collection and conduction of photo-generated current are facilitated, and series resistance of the battery can be reduced.
In S300, the absorbing layer 30 is prepared on the surface of the back electrode layer 20 away from the flexible substrate 10 by using a magnetron sputtering or Chemical Vapor Deposition (CVD) method. The absorption layer 30 is a P region of the solar cell 100. The absorbent layer 30 may be selected from any one of the following: copper Indium Gallium Selenide (CIGS), Copper Zinc Tin Sulfide (CZTS), copper indium tin sulfide (CIG), with Copper Indium Gallium Selenide (CIGS) being preferred in this application.
In S400, after the absorber layer 30 is prepared, the buffer layer 40 is prepared on the surface of the absorber layer 30 away from the back electrode layer 20 by using a chemical bath deposition method. The buffer layer 40 may be made of one of zinc sulfide, cadmium sulfide, and indium sulfide. When the absorber layer 30 is a Copper Indium Gallium Selenide (CIGS) thin film, the buffer layer 40 is preferably a CdS buffer layer thin film. The CdS thin film can match the forbidden bandwidth between the absorption layer 30 and the high resistance layer 50, reducing the band gap step and the lattice mismatch ratio between the two layers. In the process of preparing the solar cell 100, the CdS thin film is deposited first, and then the high-resistance layer 50 is deposited, so that the absorption layer 30 can be protected from being bombarded by high-energy plasma to generate defects, and the effect of protecting the absorption layer 30 is achieved.
The high resistance layer 50 is an intrinsic ZnO layer. The intrinsic ZnO film has a wider band gap (about 3.3 eV-3.6 eV), higher light transmittance and resistivity, and can transmit most of solar spectrum. In the CIGS solar cell, the high resistance layer 50 and the buffer layer 40 constitute an N region.
In S600, the window layer 60 is prepared on the surface of the high resistance layer 50 away from the buffer layer 40 by using a magnetron sputtering method. Firstly, preparing the indium tin oxide layer 61 by using a magnetron sputtering method, and then preparing an aluminum-doped zinc oxide layer 62 on the indium tin oxide layer 61 by using a magnetron sputtering method to form a composite window layer. The thickness of the aluminum-doped zinc oxide layer 62 is 0nm to 1000nm, preferably 100nm to 300 nm.
In S700, the aluminum-doped zinc oxide layer 62 may be etched into a light trapping structure in the shape of nano-pillars, nano-cones, or nano-dots in a wet etching solution. The pH value of the wet etching solution is 0-14, and is not limited herein. The thickness of the light trapping structure array obtained by etching with the wet etching liquid is 20 nm-1000 nm, and preferably 100 nm-200 nm. The maximum diameter of the nano-column, the nano-cone or the nano-point in the light trapping structure array is 10 nm-1000 nm.
In this embodiment, the back electrode layer 20, the absorber layer 30, the buffer layer 40, the high resistance layer 50, and the window layer 60 are sequentially disposed on the surface of the flexible substrate 10. Since the window layer 60 includes the ito layer 61 and the al-doped zno layer 62. Thus, the window layer 60 not only has the high optical transparency and high electrical conductivity of the ito layer 61. In addition, the aluminum-doped zinc oxide layer 62 can also be wet-etched to prepare the light trapping structures 63 arranged at intervals. Thus, the reflection of surface incident light can be reduced, the light absorption of the cell can be enhanced, the short-circuit current of the solar cell 100 can be improved, the open-circuit voltage and the filling factor of the cell can not be reduced, and the conversion efficiency of the cell can be improved. In addition, the wet etching process for preparing the light trapping structure 63 is simple, does not need a vacuum environment, has low cost, and can be directly integrated into the existing production line to realize online continuous production.
In one embodiment, in S700, the pH of the etching solution for wet etching is less than 7.
Preparing the etching solution by using pure water, wherein the pH value range is 0-7, and the preferable pH value range is 0-3. The etching solution comprises acid, alkali and salt, preferably acid, strong acid and weak base salt and weak acid and weak base salt, and more preferably acid. The reaction solution can be a mixed solution of the above solutes. And when the pH value of the etching liquid of the wet etching is less than 7, the wet etching can form an etching morphology with a good anti-reflection effect. The etching liquid for wet etching is preferably nitric acid or hydrochloric acid. Thus, the aluminum-doped zinc oxide layer 62 can be etched into a nano-cone structure, so that the light trapping structure 63 can have the best negative effect.
In one embodiment, in the S700, the wet etching temperature is 20 ℃ to 30 ℃.
In this embodiment, the temperature of the wet etching is 20 ℃ to 30 ℃. Thus, the etching of the aluminum-doped zinc oxide layer 62 has a moderate etching rate, the production efficiency cannot be influenced by the slow etching rate when the wet etching is carried out at the etching rate, the etching appearance cannot be controlled difficultly due to the fast etching rate, and the temperature is easy to control and repeat. Therefore, the aluminum-doped zinc oxide layer 62 can be etched into a nano array with the thickness of 20nm to 1000nm and the diameter of 10nm to 1000nm within a preset time, so that the light trapping structure 63 has a good light trapping effect.
In one embodiment, in S700, the etching time of the wet etching is 1min to 30 min.
In this embodiment, in S700, the etching time of the wet etching is 1min to 30 min. This can avoid the poor light trapping effect of the light trapping structure 63 caused by the excessive thickness, the excessive interval and the insufficient diameter of the light trapping structure 63 due to the too long etching time.
In one embodiment, the method for manufacturing the solar cell further includes disposing a metal grid line on the surface of the window layer 60. By plating metal grid lines on the surface of the window layer 60. This makes it possible to construct the solar cell 100. This allows carriers generated by absorption of light by the pH junction to be collected, forming a current-conducting external circuit.
In one embodiment, the flexible substrate 10 is a stainless steel, aluminum alloy, molybdenum, titanium metal coil.
In this embodiment, the flexible substrate 10 is a stainless steel, aluminum alloy, molybdenum, titanium metal coil. The roll-to-roll production method of the solar cell can be realized by using flexible materials such as stainless steel, aluminum alloy, molybdenum and titanium metal coils.
In one embodiment, the S200 includes:
s210, cleaning the flexible substrate 10 by ultrasonic cleaning;
and S220, preparing a back electrode layer 20 on the surface of the cleaned flexible substrate 10.
In this embodiment, each roll of qualified flexible substrate 10 should be cleaned before further coating. The flexible substrate 10 should be continuously transported into an ultrasonic capable cleaning machine and ultrasonically washed in a heated cleaning solution followed by ultrasonic rinsing in deionized water and drying, and the cleaned roll transferred to the next step for deposition of the back electrode layer 20.
Referring to fig. 3, the present application provides a device 70 for preparing a light trapping structure, comprising:
the conveying structure 710 is used for flatly conveying the solar cells 100 placed on the surface of the conveying structure 710;
the liquid storage tank 720, wherein etching liquid is stored in the liquid storage tank 720, so as to perform wet etching on the surface of the solar cell conveyed by the conveying structure 710;
the circulation structure 730 is disposed in the reservoir 720 for maintaining the temperature uniformity of the solution in the reservoir 720.
In this embodiment, the prepared roll of the solar cell with the ito layer 61 and the al-doped zno layer 62 is unwound, and the flat cell surface faces downward, and is transported by the transport structure 710. The surface of the solar cell roll provided with the aluminum-doped zinc oxide layer 62 is soaked in the solution surface in the liquid storage tank 720 and moves forward at a certain speed, so that wet etching of the aluminum-doped zinc oxide layer 62 is completed, and the light trapping structures 63 arranged at intervals are formed. The circulation structure 730 can make the etching solution form internal circulation, and maintain the temperature stability and uniformity of the solution, so that the light trapping structure 63 with better light trapping effect can be etched by a wet method, thereby reducing the reflection of surface incident light and enhancing the light absorption of the cell.
In one embodiment, a temperature control device 721 is disposed within the reservoir 720.
In this embodiment, a temperature control device 721 is disposed in the reservoir 720. The temperature control device 721 is disposed at the bottom or on the sidewall of the liquid storage tank 720, so that the temperature of the etching liquid in the liquid storage tank 720 can be controlled to 20-30 ℃ more accurately, and the shape of the light trapping structure 63 can be controlled more accurately, so that the light trapping structure 63 can better play a role in reducing the reflection of surface incident light, enhancing the light absorption of the cell, and improving the repeatability of the process.
In one embodiment, the delivery structure 710 includes:
a winding drum 711 provided at the head end and the tail end of the transportation path of the solar cell 100, for winding the solar cell 100 into a roll;
and a guide roller 712 disposed on the conveying path of the solar cell 100 for guiding the conveying direction of the solar cell 100.
In this embodiment, the reels 711 are disposed at the head end and the tail end of the substrate transport path for unwinding the solar cell roll. After the solar cell roll is unwound, a plurality of guide rollers 712 are located in a substrate conveying path to guide the conveying direction of the solar cell 100, and the solar cell roll is conveyed to the liquid storage tank 720 for wet etching.
In one embodiment, the apparatus 70 for preparing the light trapping structure further comprises the roller 713. The roller 713 is provided on both sides of the guide roller 712. The roller 713 serves to maintain the flatness and the pressure equalization of the solar cell 100.
In this embodiment, the surface of the solar cell 100 faces downward, soaks the surface of the solution in the liquid storage tank 720, and moves forward at a certain speed to complete wet etching. The guide roller 712, i.e., the upper and lower sides of the solar cell 100, has a plurality of rollers, so that the solar cell 100 can be kept flat and pressure-balanced. After the solar cell 100 with the wet etching surface leaves the liquid storage tank 720, the whole roll-to-roll wet etching process flow can be completed through cleaning, drying and rolling again.
The features of the above-described embodiments may be arbitrarily combined, and for the sake of clarity of description, all possible combinations of the features in the above-described embodiments are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.