Application Of Alkali Metal Doping In Cigs Solar Cell

With the rapid development of thin film solar cells, flexible copper indiumgallium selenide Cu(In,Ga)Se2(CIGS) thin film solar cells have caused widelyattention by the international photovoltaic industry. Flexible CIGS thin film solarcells have many advantages, such as high power-weight ratio, light quality, flexible,stable performance, and realization of mass production for roll-to-roll process,significantly reduction in the production cost, easy to carry and transport. With theconstantly refresh efficiency of flexible CIGS thin film solar cells, the research focuschanged accordingly, including the development of flexible CIGS solar cells withhigher efficiency, research on sodium incorporation methods, optimized low-cost andhigh-quality processes for CIGS thin films.The CIGS thin films on PI substrate were deposited at low temperature bythree-stage co-evaporation optimizing process. First of all, IGS precursor isevaporated to improve the adhesion of CIGS thin film. Secondly, a rich-Cu of CIGSthin film is deposited at appropriate temperature to obtain the large grain of CIGS thinfilm. And last, a poor-Cu of CIGS thin film on the top is evaporated by four-elementco-evaporation progress.In order to find the optimized evaporate condition of NaF, it can be changed byevaporate temperatures, evaporate time and substrate temperatures. And the structural,micrograph and electrical properties of CIGS thin film have been investigated bypre-deposition and post-deposition treatment of NaF. The results show that electricNa effects on CIGS thin film solar cells are enhancements of carrier concentrationand of thin film conductivity, and finally promote the growth of CIGS thin film, especially pre-deposition treatment of NaF can show a double-peek phenomenon witha XRD pattern. The phenomenon is caused by inter-diffusion of elements. Therefore,it is suggested that post-deposition treatment of NaF is more optimized method.Finally, Na can sufficiently diffuse into CIGS thin film of post-depositonincorporation of NaF with different annealed methods. By changing annealedatmosphere, annealed time and annealed temperatures, it can be achieved theoptimized annealing process with air vapor at the annealed temperature of150℃during two minutes. The application of three-stage co-evaporation optimized processfor deposition CIGS thin film and post-deposition Na incorporation for the process ofsolar cells have been achieved a higher conversion efficiency.