Preparation method of lightweight flexible cadmium telluride film and lightweight flexible cadmium telluride substrate

Abstract

The present invention relates to the field of solar power generation, and in particular to a method for preparing a lightweight flexible cadmium telluride film and a lightweight flexible cadmium telluride substrate, which comprises the following steps: S1. Selecting a flexible ultra-thin conductive glass with a cadmium sulfide layer deposited on the surface as a substrate for electroplating, and using a flat titanium plate suction cup to vacuum adsorb the back of the conductive glass to fix the conductive glass; S2. Placing the conductive surface of the adsorbed and fixed conductive glass downward in an electroplating tank of a special structure, wherein the conductive glass is the cathode during electroplating, and the bottom titanium plate of the electrolytic tank is the anode. The elastic needles arranged in an array are installed on the titanium plate and connected to the cathode wire, and the needle tip contacts the conductive layer of the conductive glass; S3. The electrolytic tank is circulated with an electroplating solution, and the electroplating is started to obtain a lightweight flexible cadmium telluride film substrate. The method for preparing a flexible cadmium telluride film substrate provided by the present invention has the characteristics of being lightweight, flexible, and having uniform composition thickness, and meets the requirements for flexible photovoltaic solar cells in future photovoltaic building integration.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, in particular to a method for preparing a lightweight flexible cadmium telluride film and a lightweight flexible cadmium telluride substrate. Background Art

[0002] Building-integrated photovoltaics (BIPV) usually require lightweight or even flexible solar cells. Currently, flexible solar cells are prepared mainly in four ways: the first is to deposit amorphous silicon on a flexible substrate and encapsulate the front side with a flexible resin; the second is to cut the rigid crystalline silicon cell into small pieces and then connect them in series and parallel, and encapsulate the front and back sides with flexible protective materials; the third is to deposit the copper indium gallium selenide thin film on a flexible stainless steel plate and encapsulate the back side with a flexible protective material; the fourth is to use a low-temperature process to directly deposit the perovskite light-absorbing layer on a transparent flexible substrate and encapsulate the back side with a flexible protective material. These four flexible cells have problems such as low efficiency, high raw material cost, complex process or stability. In fact, BIPV faces the reality that there are no cells available or the cost is too high. Cadmium telluride thin-film solar cells have the characteristics of abundant raw materials, simple preparation process, high photoelectric conversion efficiency, good weak light power generation performance and low cost. These characteristics give cadmium telluride cells a natural advantage in the field of BIPV. However, at present, cadmium telluride cells are only suitable for the construction of traditional photovoltaic power stations, and their application in the field of BIPV is still greatly limited. The reason is that mature cadmium telluride solar cells mainly use the vapor phase method to deposit cadmium telluride films, but the temperature of the vapor phase method is high, close to or even reaching the softening temperature of the glass substrate, and thick conductive glass must be used to prevent high temperature deformation. Thick conductive glass not only increases the weight of the battery itself but also loses its flexibility, limiting its application in the field of architecture, so it needs to be redesigned. Summary of the invention

[0003] 1. Technical issues to be solved

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a lightweight and flexible cadmium telluride film and a lightweight and flexible cadmium telluride substrate. The ultra-thin conductive glass substrate not only reduces the weight of future batteries but also maintains flexibility. The low-temperature electroplating method for depositing the cadmium telluride film can effectively avoid glass deformation caused by high temperature. At the same time, the electrolytic cell design of the array-type elastic cathode needle can maintain the potential uniformity of the large-area conductive glass used as the cathode, thereby obtaining a cadmium telluride film with uniform composition and thickness, etc., and solves the problem of glass deformation caused by high temperature when preparing the cadmium telluride film. The thick conductive glass used to adapt to the high-temperature film forming process has the problems of large thickness, heavy weight and poor flexibility.

[0005] (II) Technical solution

[0006] In order to realize the above-mentioned ultra-thin conductive glass substrate, which not only reduces the weight of future batteries but also maintains flexibility, the low-temperature electroplating method for depositing cadmium telluride thin films can effectively avoid glass deformation caused by high temperature, and the electrolytic cell design of the array-type elastic cathode needle can maintain the potential uniformity of the large-area conductive glass as the cathode, so as to obtain a cadmium telluride thin film with uniform composition and thickness. The present invention provides the following technical solutions:

[0007] A method for preparing a lightweight and flexible cadmium telluride film comprises the following steps:

[0008] S1. Select a flexible ultra-thin conductive glass with a cadmium sulfide layer deposited on the surface as the electroplating substrate, and use a flat titanium plate suction cup to vacuum absorb the back of the conductive glass to fix the conductive glass and prevent the conductive glass from being deformed by force;

[0009] S2. Place the conductive surface of the adsorbed and fixed conductive glass downward in a specially structured electroplating tank, press and seal it tightly. The conductive glass is the cathode during electroplating, and the titanium plate at the bottom of the electrolytic tank is the anode. The titanium plate is installed with elastic needles arranged in an array and connected to the cathode wire. The needle tip contacts the conductive layer of the conductive glass to ensure that the voltage at all locations of the conductive layer of the glass is uniform.

[0010] S3. The electroplating solution is circulated into the electrolytic cell to start electroplating, and the electroplating is stopped when the thickness of the CdTe film reaches the required value. The conductive glass after electroplating is taken out and the electroplating solution on the surface is washed off with water, and then the glass is dried with air to obtain a lightweight and flexible cadmium telluride thin film substrate.

[0011] Preferably, in step S1, an ultra-thin conductive glass with a cadmium sulfide coating is selected as a deposition substrate, and the conductive glass may be either ITO glass or FTO glass.

[0012] Preferably, in step S1, a cadmium sulfide layer is coated on the surface of the ultra-thin conductive glass, and the coating method may be a physical sputtering method or a chemical bath deposition method, and the thickness of the cadmium sulfide layer should not be higher than 80 nm.

[0013] Preferably, in step S2, the electrolytic cell uses a titanium plate equipped with array-type elastic needles as the anode.

[0014] Preferably, in step S3, the conductive glass is fixed by vacuum adsorbing the back side of the conductive glass with a flat titanium plate suction cup.

[0015] Preferably, in step S3, the method for depositing the cadmium telluride thin film is low-temperature electroplating technology; and the electroplating process uses a circulating electroplating solution.

[0016] Another technical problem to be solved by the present invention is to provide a lightweight and flexible cadmium telluride substrate, including an anode titanium plate, an elastic electroplating needle is arranged on the top of the anode titanium plate, a cadmium sulfide window layer is arranged on the top of the elastic electroplating needle, a flexible conductive glass is arranged on the top of the cadmium sulfide window layer, a titanium plate suction cup is arranged on the top of the flexible conductive glass, and four through air holes are arranged in the middle of the titanium plate suction cup.

[0017] Preferably, the elastic electroplating needle is elastic, and the tip of the elastic electroplating needle is in contact with the flexible conductive glass.

[0018] Preferably, the surface coating of the anode titanium plate of the elastic electroplating needle is a mixed metal oxide, the composition of which is IrO2, RuO2-IrO2S3 or TaO2-IrO2.

[0019] Preferably, the titanium plate suction cup is engraved with grooves and has a through hole in the local groove, wherein the groove width and depth should be moderate.

[0020] (III) Beneficial effects

[0021] Compared with the prior art, the present invention provides a method for preparing a lightweight flexible cadmium telluride film and a lightweight flexible cadmium telluride substrate, which have the following beneficial effects:

[0022] 1. The preparation method of the lightweight flexible cadmium telluride film and the lightweight flexible cadmium telluride substrate are obtained by adopting a flexible ultra-thin conductive glass substrate and a low-temperature electroplating method to deposit the cadmium telluride film. The ultra-thin conductive glass substrate not only reduces the weight of future batteries but also maintains flexibility. The low-temperature electroplating method for depositing the cadmium telluride film can effectively avoid glass deformation caused by high temperature. At the same time, the electrolytic cell design of the array-type elastic cathode needle can maintain the potential uniformity of the large-area conductive glass as the cathode, thereby obtaining a cadmium telluride film with uniform composition and thickness.

[0023] 2. The preparation method of the lightweight flexible cadmium telluride film and the lightweight flexible cadmium telluride substrate provide conditions for the next step of preparing lightweight flexible cadmium telluride thin film photovoltaic cells that truly meet the requirements of photovoltaic building integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the patented electroplated flexible cadmium telluride battery substrate of the present invention.

[0025] In the figure: 1. Elastic electroplating needle; 2. Cadmium sulfide window layer; 3. Flexible conductive glass; 4. Anode titanium plate; 5. Titanium plate suction cup; 6. Through-hole. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A method for preparing a flexible cadmium telluride substrate comprises the following steps:

[0028] S1. Select a flexible ultra-thin conductive glass with a cadmium sulfide layer deposited on the surface as the electroplating substrate, and place the back of the glass close to the surface of a flat titanium plate with shallow grooves, and fix it by vacuum adsorption;

[0029] S2. Place the conductive surface of the adsorbed and fixed conductive glass downward in an electrolytic cell of a special structure, press and seal it, the conductive glass serves as the cathode during electroplating, the titanium plate at the bottom of the electrolytic cell serves as the anode, elastic needles distributed in an array are installed on the surface of the titanium plate at the bottom of the electrolytic cell, and the cathode wire is connected. Under pressure, the elastic needles are elastically compressed so that the needle tips of all needles contact the conductive layer of the conductive glass to ensure uniform voltage on the conductive layer;

[0030] S3. The electroplating solution is circulated into the electrolytic cell to start electroplating until the thickness of the CdTe film reaches the required value. The conductive glass after electroplating is taken out and the plating solution on the surface of the electroplated cadmium telluride is washed off with water. The glass is then dried with air to obtain a lightweight and flexible cadmium telluride thin film substrate.

[0031] Where S1 is:

[0032] Select flexible ultra-thin conductive glass, deposit a cadmium sulfide window layer on its conductive surface, and adsorb the back of the glass on a titanium plate with shallow grooves of good flatness. The thickness of the conductive glass is 0.6mm-1.6mm, so that the glass has a certain flexibility and light weight. The conductive layer can be a light-transmitting conductive metal oxide such as ITO or FTO; the method of depositing the cadmium sulfide window layer can be physical sputtering or chemical bath deposition. The thickness of the cadmium sulfide layer should be less than 80nm, so that it will not produce a significant potential drop during electroplating; the surface of the flat titanium plate is distributed with parallel and vertical interconnected shallow grooves, the depth of the shallow grooves should be less than 1.0mm, and the groove width should be no more than 2.0mm, so as to avoid excessive deformation of the glass during vacuum adsorption and affect the flatness of the glass. There are multiple through holes in the grooves connected to the vacuum system to provide vacuum conditions for adsorbing the conductive glass.

[0033] Where S2 is:

[0034] The adsorbed and fixed conductive glass is placed with the conductive surface facing downward on the electrolytic cell. The bottom of the electrolytic cell is an array of porous titanium plates as an electroplating anode. Electroplating elastic needles can be installed in the holes of the titanium plate. Pressure is applied to make the conductive surface of the conductive glass form good electrical contact with the needle tips of all the elastic needles.

[0035] The elastic needles are all electrically connected to the cathode wire, and the surface of the needle is coated with an acid-resistant insulating layer, and the needle tip is exposed so that the needle is electrically connected to the cathode wire and the conductive layer of the glass at the same time; the elastic needle can be deformed under pressure to ensure that the needle tips of all needles can contact the conductive layer of the glass; the cathode needle should be insulated from the anode titanium plate during installation to prevent the cathode and the anode from forming a short circuit. The insulating layer wrapped on the needle surface is to isolate the conductive needle from the electroplating solution to prevent cadmium telluride from being electroplated on the surface of the conductive needle. The insulating layer can be polytetrafluoroethylene or parylene that is resistant to acid and alkali corrosion.

[0036] Among them, the porous titanium anode plate is coated with a mixed metal oxide (MMO) layer on its surface. MMO is an oxygen-generating catalyst, which is beneficial to reducing the oxygen-generating overpotential to reduce the energy consumption during electroplating. The hole spacing of the porous array should be appropriate, which should not only ensure that the potential drop generated by the cathode needle installed therein on the conductive glass will not affect the uniformity of the composition and thickness of the electroplated cadmium telluride film, but also consider that the line width of the laser scribing when the battery is formed later just covers the pinhole left by the needle tip during electroplating.

[0037] The electrolytic cell is a three-electrode system, which is convenient for accurately controlling the electroplating potential to ensure the composition ratio of the cadmium telluride layer. The conductive layer of the conductive glass is the cathode, the anode titanium plate coated with MMO is the anode, and the metal cadmium wire is the reference electrode and is installed at the liquid outlet of the electrolytic cell.

[0038] Among them, S3 is:

[0039] An acidic electroplating solution is introduced into the electrolytic cell to start electroplating until the thickness of the CdTe film reaches the required value. After taking out, the electroplating solution on the surface is washed off with water and dried with air to obtain a lightweight and flexible cadmium telluride thin film substrate.

[0040] The acidic electroplating solution circulates during the electroplating process to compensate for the fluctuation of local substance concentration caused by electroplating consumption and maintain the stability of the electroplating solution concentration.

[0041] Wherein, the thickness of the electroplated cadmium telluride layer is 0.8um-3.0um.

[0042] Among them, the process of cleaning the surface of the cadmium telluride film should be carried out immediately after the electrolytic cell is opened to prevent the electroplating solution on the surface from evaporating quickly and crystallizing at the electroplating temperature, so as to reduce the difficulty of cleaning; at the same time, cleaning and drying should be carried out before the electroplated conductive glass is desorbed from the surface of the titanium plate to prevent the flexible glass from being damaged due to excessive deformation.

[0043] A flexible solar cell is prepared by the above-mentioned method for preparing a flexible solar cell.

[0044] From the above description, it can be seen that a lightweight and flexible cadmium telluride substrate is prepared by the above preparation method, and cadmium telluride substrates of different area sizes are further provided to obtain flexible batteries with different power or current and voltage. The substrate area can be controlled by designing and selecting electrolytic cells or flexible glasses of different sizes, or by cutting a large-area flexible substrate into small-area substrates.

[0045] A lightweight and flexible cadmium telluride substrate is obtained by depositing a cadmium telluride film using a flexible ultra-thin conductive glass substrate and a low-temperature electroplating method. The ultra-thin conductive glass substrate used not only reduces the weight of future batteries but also maintains a certain degree of flexibility. The low-temperature electroplating technology can effectively avoid glass deformation caused by high temperatures. The array-type elastic cathode needles designed in the electroplating tank can maintain the uniformity of the cathode potential applied to the large-area conductive layer, thereby obtaining a cadmium telluride film with uniform composition and thickness. The technical solution provided by the present invention is used to prepare a lightweight and flexible cadmium telluride substrate, and a lightweight and flexible cadmium telluride thin-film photovoltaic cell that meets the requirements of photovoltaic building integration can be prepared.

[0046] Example 1

[0047] See also Figure 1 As shown, a method for preparing a lightweight flexible cadmium telluride substrate comprises the following steps:

[0048] S1. A 0.6 mm thick flexible ultra-thin ITO conductive glass is deposited with a cadmium sulfide layer by chemical bath deposition. The thickness of the cadmium sulfide layer is about 60 nm. The back of the glass is pressed against a titanium plate suction cup and fixed by vacuum adsorption.

[0049] S2. Place the ITO conductive glass fixed by vacuum adsorption with the conductive surface facing downward in an electroplating tank, and apply pressure to cause all elastic needles in the electroplating tank to deform by compression, so that the conductive needle tips of all needles are in contact with the conductive layer.

[0050] S3, start the circulation pump to make the electroplating solution circulate in the electroplating tank, start the electroplating power supply, and stop electroplating when the thickness of the cadmium telluride electroplating layer reaches 3.0um, take out the cadmium telluride film, clean it, blow it dry, and obtain a lightweight and flexible cadmium telluride substrate.

[0051] Example 2

[0052] See also Figure 1As shown, a method for preparing a lightweight flexible cadmium telluride substrate comprises the following steps:

[0053] S1. Select a 1.6 mm thick FTO conductive glass with a cadmium sulfide layer deposited by physical sputtering. The thickness of the cadmium sulfide layer is about 45 nm. The back of the glass is pressed against a titanium plate suction cup and fixed by vacuum adsorption.

[0054] S2. Place the FTO conductive glass fixed by vacuum adsorption with the conductive surface facing downward in an electroplating tank, and apply pressure to cause all elastic needles in the electroplating tank to deform by compression, so that the conductive needle tips of all needles are in contact with the conductive layer.

[0055] S3, start the circulation pump to make the electroplating solution circulate in the electroplating tank, start the electroplating power supply, and stop electroplating when the thickness of the cadmium telluride electroplating layer reaches 2.0um, take out the cadmium telluride film, clean it, blow it dry, and obtain a lightweight and flexible cadmium telluride substrate.

[0056] Example 3

[0057] See also Figure 1 As shown, a method for preparing a lightweight flexible cadmium telluride substrate comprises the following steps:

[0058] S1. Select a 1.1 mm thick FTO conductive glass with a cadmium sulfide layer deposited by a chemical bath method. The thickness of the cadmium sulfide layer is about 80 nm. The back of the glass is pressed against a titanium plate suction cup and fixed by vacuum adsorption.

[0059] S2. Place the FTO conductive glass fixed by vacuum adsorption with the conductive surface facing downward in an electroplating tank, and apply pressure to cause all elastic needles in the electroplating tank to deform by compression, so that the conductive needle tips of all needles are in contact with the conductive layer.

[0060] S3, start the circulation pump to make the electroplating solution circulate in the electroplating tank, start the electroplating power supply, and stop electroplating when the thickness of the cadmium telluride electroplating layer reaches 0.8um, take out the cadmium telluride film, clean it, blow it dry, and obtain a lightweight and flexible cadmium telluride substrate.

[0061] The lightweight and flexible cadmium telluride substrate is prepared by the method.

[0062] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a lightweight and flexible cadmium telluride film, characterized in that: The following steps are involved: S1. Select a flexible ultra-thin conductive glass with a cadmium sulfide layer deposited on the surface as the electroplating substrate, and use a flat titanium plate suction cup to vacuum absorb the back of the conductive glass to fix the conductive glass and prevent the conductive glass from being deformed by force; An ultra-thin conductive glass with a cadmium sulfide coating is selected as a deposition substrate, and the conductive glass can be either ITO glass or FTO glass; The cadmium sulfide layer is coated on the surface of the ultra-thin conductive glass, and the coating method can be a physical sputtering method or a chemical bath deposition method, and the thickness of the cadmium sulfide layer is equal to or less than 80nm; S2. Place the conductive surface of the adsorbed and fixed conductive glass downward in a specially structured electroplating tank, press and seal it tightly. The conductive glass is the cathode during electroplating, and the titanium plate at the bottom of the electrolytic tank is the anode. The titanium plate is installed with elastic needles arranged in an array and connected to the cathode wire. The needle tip contacts the conductive layer of the conductive glass to ensure that the voltage at all locations of the conductive layer of the glass is uniform. The electrolytic cell uses an anode titanium plate (4) equipped with array-type elastic needles as an anode; An elastic electroplating needle (1) is arranged on the top of the anode titanium plate (4), a cadmium sulfide window layer (2) is arranged on the top of the elastic electroplating needle (1), a flexible conductive glass (3) is arranged on the top of the cadmium sulfide window layer (2), a titanium plate suction cup (5) is arranged on the top of the flexible conductive glass (3), and four through-holes (6) are arranged in the middle of the titanium plate suction cup (5); The elastic electroplating needle (1) is elastic, and the needle tip of the elastic electroplating needle (1) is in contact with the flexible conductive glass (3); The surface coating of the anode titanium plate (4) of the elastic electroplating needle (1) is a mixed metal oxide, the composition of which is IrO2, RuO2-IrO2S3 or TaO2-IrO2; The titanium plate suction cup (5) is engraved with grooves and has a through-hole (6) in a local groove; S3. The electroplating solution is circulated into the electrolytic cell to start electroplating, and the electroplating is stopped when the thickness of the CdTe film reaches the required value. The conductive glass after electroplating is taken out and the electroplating solution on the surface is washed off with water, and then the glass is dried with air to obtain a lightweight and flexible cadmium telluride thin film substrate.

2. The method for preparing a lightweight and flexible cadmium telluride film according to claim 1, characterized in that: In step S3, the conductive glass is fixed by vacuum adsorbing the back side of the conductive glass with a flat titanium plate suction cup.

3. The method for preparing a lightweight and flexible cadmium telluride film according to claim 1, characterized in that: In the step S3, the method for depositing the cadmium telluride film is low-temperature electroplating technology; the electroplating process uses a circulating electroplating solution.

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