The Preparation and Depositing Mechanism Investigation of CIS/CIGS Absorber Layer for Solar Cells by the Induced Co-Deposition

In this project, we will cooperate with professor Novikov, Head of Lab. of Photoelectrophysics, Institute of Problems of Chemical Physics, IPCP RAS, to study the preparation and depositing mechanism investigation of CIS/CIGS absorber layer for solar cells by the induced co-deposition. Generally, the flux balance by optimizing the deposition conditions of the constitute concentrations and deposition potentials was used to prepare CIS/CIGS absorber layer by one-step electrodeposition. Its disadvantage is that the concentration and potential ranges for the formation of stoichiometric product are often narrow. Thus, small and unavoidable variations in concentrations and potential may result in large changes in the film compositions. It will result in the reproducibility problem especially for large area applications. To overcome this problem, the induced co-deposition method is investigated. Its film composition is determined by thermodynamics. It is much less sensitive to electrolyte composition and deposition potential than that based on the flux balance method. Thus, it provides more stable and suitable processes for large area application. Professor Novikov specialized in chemical method to prepare thin film by theoretical and experimental investigation and Associate Professor Jeng specialized in the fabrication processing of semiconductor devices for solar cells and light-emitting devices. By way of combining these two kinds of technologies, we expect that a high efficiency and low cost CIS/CIGS solar cells can be achieved by the international cooperation research. The research results will be shared by these two research teams. Recently, a good adhesion and low sheet resistance of sputtered Mo film can be achieved by two-stage sputtering with different pressures and r.f. power. In addition, a very low resistivity film of ZnO is also attainable in Chang Gung University. In this three-year project, except investigating the induced co-deposition method, we will integrate and optimize these process parameters to obtain a high efficiency CIS/CIGS solar cell. In the first year, we will control the amount of Na-outdiffusion by optimizing the process parameters for fabricating barrier layer. A proper amount of Na-outdiffusion will be helpful to improve the efficiency of solar cell. The CIGS film quality is not good for too few Na-outdiffusions. Nevertheless, for too much the CIGS film easily peels off. Accurately adjusting Na-outdiffusion quantity is an important issue. In the second year, the annealing or selenization process parameters will be extensively examined by comparing the temperature profiles of two-stage and multi-stage selenization. In the third year, contact metal pattern and anti-reflective layer are studied. The randomly textured transparent conductive oxides and the application of periodic light grating couplers are investigated. The periods and groove depths of transparent gratings made of zinc oxide are tuned independently from each other. Other different anti-reflective techniques will be also examined and compared to obtain a high transmittance method. It is believed that a high efficiency CIGS solar cell can be achieved by integrating and optimizing these process parameters.

Project ID:PB10001-1310
External Project ID:NSC99-2923-E182-001-MY3