Cigs Thin Film Solar Cell Layer Of The Preparation And Characterization Of Key Function

Copper indium gallium selenide (CIGS) thin film solar cell is one of the most promising solar cells for its high conversion efficiency, low cost, strong radiation resistance and excellent weak light response. The state-of-the-art conversion efficiency of small area CIGS solar cell has reached20.3%, which is closed to that of crystalline silicon solar cell. However, the large-scale industrilization of CIGS solar cell lags far behind that of crystalline silicon solar cell. The reason is mainly due to the complexity of the manufacturing procedure of CIGS thin film which makes it difficult to assure the uniformity in a large area. On the other hand, the multi-layered heterojunction structure of CIGS/CdS/ZnO makes the photoelectric performace of the cells more sensible to the physical properties of each layer.In this work, we developed a one-step process for the deposition of CIGS absorber layers by magnetron sputtering from a single CIGS quaternary target to solve the first problem mentioned above and make large-scale commercial devepoment of CIGS solar cell possible. The effect of sputtering process was systematically studied. On the next stage, the buffer layer and window layer were sequently deposited by chemical bath deposition and magnetron sputtering. Finally, CIGS devices were fabricated and tested. The main research content is as following.1) CIGS absorber layers were deposited by one-step sputtering from a single quaternary chalcogenide target. The effect of substrate temperature, chamber pressure, sputtering power on the properties of the thin films were studied in detail. It was found that the as-sputtered CIGS layers showed homogeneous and compact microstructure, and exhibited single chalcopyrite phase structure, which were well in accordance with the phase structure of the source target. CIGS thin films with different microstructure and composition were deposited by changing the sputtering process parameters. The CIGS thin films deposited at higher substrate temperature, higher chamber pressure, and higher sputtering power showed larger grain and stronger (220)/(204) orientation preference, with a composition close to the stoichiometric ratios.2) CdS thin films were deposited by chemical bath deposition(CBD), and the effects of process parameters on CdS films were also studied. It was found that CdS thin films deposited by CBD with a short deposition time showed homogeneous and compact microstructure. The crystallinity and photoelectric characteristic of CdS films were improved through heat treatmet with a CdCb layer on CdS layer.3) Double-layer ZnO thin films were deposited by magnetron sputtering, and the effects of sputtering power and chamber pressure on the properties of ZnO:Al thin films were systematically studied. It was found that proper sputtering power and chamber pressure used in sputtering process could enhance the photoelectric property of ZnO:Al thin films.4) CIGS solar cells were successfully fabricated with each layer optimized. It was easily found that one-step sputtering process was a promising and low cost process for CIGS absorber layer depostion.