①Silicon-based thin film module
Silicon-based thin film batteries include amorphous silicon thin film batteries, microcrystalline silicon thin film batteries, and polycrystalline silicon thin film batteries. At present, amorphous silicon thin film battery products are important in the market. The band gap of amorphous silicon is 1.7eV, and p-type or n-type a-Si can be obtained by doping boron or phosphorus. In order to improve efficiency and improve stability, p-i-n/p-i-n double-layer or multi-layer structured laminated batteries have also been developed.
②Copper indium gallium selenide thin film module
Copper indium gallium selenide [Cu(In,Ga)Se2, referred to as CIGS] thin-film solar cells have a high photoelectric conversion efficiency, which can reach 22.6% or more. Although it does not reach the conversion efficiency of arsenic image solar cells currently used in space, Its low cost, light weight, good stability, strong resistance to radiation, can be fabricated on a flexible substrate to achieve a variety of solar cell wing structure designs and folding and unfolding method designs. It is considered to be the most promising new space application. A generation of solar cells.
Copper indium gallium selenium thin film solar cells belong to polycrystalline compound semiconductor heterojunction solar cells. Its predecessor was copper indium selenium (CulnSe2, abbreviated as CIS) solar cell. The typical structure of CIGS thin-film solar cells is Al/MgF2/ZnO/CdS/CIGS/Mo/substrate, and it is supported by the substrate. Usually low-cost soda lime glass is used as the substrate for component production. In addition, polymers, metal boxes, stainless steel, etc. are also used as substrate materials. Studies have shown that the key technology for the development of CIGS thin-film solar cells is to reduce the thickness of the absorption layer to 1 μm or less. This will reduce the amount of rare metals, help reduce costs and increase productivity. Studies have shown that the thickness of the absorber layer can be reduced to 0.7μm. If it continues to be thinned, it will affect the open-circuit voltage, influence factor and short-circuit current of the solar cell, thereby affecting its performance.
The absorption layer film of CIGS thin-film solar cells is prepared by physical vapor deposition, the buffer layer CdS or CdZnS (O, OH) is prepared by chemical bath method (CBD), and the ZnO film is prepared by chemical vapor deposition or sputtering. The new technology of buffer layer preparation adopts vacuum deposition method to replace the traditional chemical bath method. In the preparation of the absorption layer, in addition to the traditional evaporation method, two technical routes have been developed: one is the vacuum deposition method (such as the sputtering method) to prepare the Cu-In-Ga metal prefabricated film, and then the H2Se gas selenization is used to prepare it. CIGS thin film; the second is to use non-vacuum technology to produce semiconductor thin film with nano-particle “ink” (paste) printing reaction.
③Cadmium telluride thin film module
Cadmium telluride thin-film solar cells are photovoltaic devices constructed by sequentially depositing multiple layers of thin films on glass or other flexible substrates. Generally, standard cadmium telluride thin film solar cells are composed of five layers, and cadmium telluride and cadmium sulfide are the main components of cadmium telluride thin film solar cells. The principle of cadmium telluride solar cells: N-type CdS and P-type CdTe form a PN junction. When light hits the surface of the solar cell, a part of the photons are absorbed; the energy of the photons is transferred to the solar cell, causing the electrons to undergo transitions and become free electrons. The two sides of the PN junction gather to form a potential difference. When the circuit is connected externally, under the action of this voltage, a current will flow through the external circuit to produce a certain output power.
As a good absorber material, cadmium antimonide is widely used in thin-film solar cells. After years of research and research by scientists, the cadmium telluride thin-film solar cell with the mainstream structure shown in Figure 2 is basically formed. The top order is: conductive transparent glass (TCO glass), PN junction (N-CdS with a thickness of about 100nm and P-CdTe with a thickness of 3~5μm), a low-resistance contact layer (ZnTe), and a metal back electrode (Figure 2).
④Dye-sensitized module
Dye-sensitized thin-film solar cell (DSSC) is a new type of solar cell. It has the advantages of simple production, low raw material cost, simple process and high photoelectric conversion efficiency, and has become one of the candidates to replace silicon-based solar cells. A standard dye-sensitized solar cell usually consists of the following parts: a conductive substrate coated with a conductive film, a porous semiconductor nano-film, a dye photosensitizer, an oxidation-reduction electrolyte, a counter electrode, and are connected by an external circuit.
There are many wide band gap materials that can be used as anode materials for dye-sensitized solar cells. At present, titanium dioxide-based liquid cells have achieved the highest photoelectric conversion efficiency. However, since the transmission of electrons in the titanium oxide nanoparticles is relatively slow, the system also requires a slower redox electrolysis pair, which causes a large amount of open circuit voltage loss, resulting in unsatisfactory battery efficiency. Therefore, it is necessary to have a semiconductor material with higher electron mobility as a substrate with a high specific surface area, so that electrons can be transported faster to realize the further development of dye-sensitized solar cells. Tin dioxide is one of them.
However, the efficiency obtained by tin oxide-based batteries is not ideal. This is because there are a large number of trap states in tin dioxide with a high specific surface area, which results in the electron interception rate caused by the electrolyte being much faster than that of titanium oxide. This problem can be solved by covering wide band gap semiconductor materials and insulating materials on the surface.
⑤Gallium arsenide thin film module
Gallium arsenide (GaAs) thin film battery is a thin film solar cell made by growing GaAs thin film on a single crystal silicon substrate by chemical vapor deposition. It has a direct band gap of 1.424 eV and a high conversion efficiency of more than 30%. It has been applied very early Solar panels for artificial satellites. However, gallium arsenide batteries are expensive and arsenic is a toxic element, so they are rarely used on the ground.
