Preparation Cu (In, Ga) Se₂ Thin Film By Sputtering Alloy Target And Its Properties Study

Copper indium gallium selenium (CIGS) thin film solar cell is one of the most efficient thin-film technologies, with enormous potential to make new applications such as integration with building materials cost effective and viable. The highest conversion efficiency of small area sized cells is up to 20% and the module efficiency high to 16%. CIGS thin film solar cells have long service life and stable performance, low production costs, strong anti-radiativeness, excellent weak light response and high efficiency characteristics. But the current fabrication technology faces a lot of challenges due to its relatively complicated manufacturing procedures and device structures. The total installed world photovoltaic power generation is around 25GW, however, CIGS thin film solar cells take up a less than 5% PV market share. Therefore, new type and low cost methods which are apt to achieve mass production need to be developed for practical industrial applications.In this thesis, CIGS light absorbing layers were fabricated by magnetron sputtering technology using quaternary CIGS chalcogenide targets. Sputtering power, working pressure, target compositions and post-annealing process on the structure as well as photoelectric properties of CIGS thin film were systematically studied. It is found that CIGS thin films with smooth surface structure, good photoelectric properties and preferred (112) phases can be obtained under the value of sputtering power is RF 130W, working pressure is 1.3 Pa, respectively. In addition, it also displayed that post-annealing treatment make CIGS films recrystallization and can compensate for the loss mass of Se elements in sputtering process completely, which resulted in better crystallinity and photoelectric characteristics of film. Furthermore, the preparation parameters of CdS buffer layer deposited by chemical bath deposition method (CBD) are systematically researched as well. By adjusting the ammonia concentration and other reaction conditions, high quantity CdS film buffer layer can be prepared for application in solar cells. To evaluate the properties of these films, CIGS thin film solar cells with a typical glass/Mo/CIGS/CdS/i-ZnO/Al- ZnO/Ag structure were fabricated. The photocurrent density of the manufactured solar cell is high up to 24.75 mA/cm2 at the light intensity of 100 mW/cm2 under AM 1.5 illumination at room temperature 25℃. The manufactured CIGS solar cell shows an efficiency of up to 8% with the active area of about 0.4 cm2.