The Simulation And Preparation Of Planar Heterojunction Perovskite Solar Cells

Photovoltaic devices have captured increasing attention due to theirs low-cost, environmentally friendly, inexhaustlble features. With good performance and rapid pace of development, the perovskite solar cells have become a new hot spot of organic thin film solar cells. The planar perovskite solar cells, with easy fabrication and high photoelerctric conversion efficiency, have become a new direction of development. There are mang problems in the further development of the perovskite solar cells, such as stability, reproducibility, large area preparation, environmental pollution and theoretical research.This paper has researched some simple problems of the planar perovskite solar cells form the theoretical simulation and experimental preparation and given a brief introduction of the thin film CZTS.(1) Planar perovskite solar cells have been simulated, which calculates both the optical and electronic responses of a solar cell structure. 1) The effect of the carrier diffusion length, the relative permittivity of absorber layer and the valence band offset of absorber/HTM on the performance of the solar cells is carefully investigated. 2) The quality of absorber is very crucial to the performance of perovskite solar cells, where the PECs and the optimum absorber thickness increase with the increase of diffusion length. 3) The values of dielectric constant will filter down into the potential drop in bulk and ultimately into the collection of photo-generated carriers, and it should not exceeds 40 indicated. 4) The position of the valence band of the HTM will affects the transport of hole, and the optimum position of the valance band of the HTM is derived to be 0.0-0.12 e V lower than corresponding band of the absorber. However, with the double HTMs design, the selection of HTMs will be wider. The simulation results based on this study would offer the insight and understanding of the characteristics of CH3NH3 Pb I3 films and working mechanism of device, and be useful for further design optimization of perovskite solar cells.(2) To the perovskite absorber, phase transition temperature is about 58.9℃, and the decomposition temperature is about 117℃. Pb I2 thin film prepared by auxiliary liquid vapor vacuum deposition method is poor, and the condition of 50A-6min is excellent. The optimal soaked time of 10 min is obtained by the Pb I2 thin film soaked in the CH3NH3 I isopropyl alcohol solution. The cost of planar perovskite solar cells can be reduced by the Spiro-OMe TAD and Cu I orgnic/inorganic double HTMs structure.(3) In this paper, not only qualitative preparation of CZTS, but also quantitative annlysis the impact of different elements of the molar ratio in the CZTS thin film. We obtained the condition of Zn/Sn=1.2 or 1.3, Cu/(Zn+Sn)=0.8 or 0.9 is better to the preparation of CZTS thin film.