The Influence of Temperature on Phase Transition of Perovskite Materials Using the First-principles Method
Since developing perovskite solar cells, the photoelectric conversion efficiency has leapt while the stability of perovskite materials is a significant factor restricting the further development of perovskite solar cells. In practical applications, temperature is an important factor influencing the stability of perovskite materials. By using the first-principles method, the phase structures and band gaps of CH3NH3PbI3, CH(NH2)2SnI3, CsPbI3 and CsSnI3 were calculated to analyze the influence of phase transition on structures and band gaps. INTRODUCTION Perovskite solar cells have attracted numerous researchers due to favorable light absorption and transmission characteristics in recent years. The perovskite solar cells were first introduced into photovoltaic field in 2009, showing a photoelectric conversion efficiency of 3.8% [1] , which gradually improved [2-6] . By the end of 2016, the photoelectric conversion efficiency had reached to 22.1% [7] . Although perovskite materials greatly improve in efficiency, stability is always one of factors restricting the further development of perovskite materials. Changes of some perovskite materials with temperature cause the phase transition. Therefore, investigating the phase transition of materials at different temperatures and the influence of the transition on structures and band gaps of materials exerts an extremely important significance on developing new perovskite materials with high stability. By employing the first-principles method, the study optimized structures and calculated electronic structures of phases of CH3NH3PbI3, CH(NH2)2SnI3, CsPbI3 and CsSnI3 at different temperatures. By doing so, the influence law of temperature changes on material structures and band gaps was analyzed, which provides a basis for exploring perovskite materials which can sustain stable at different temperatures. First author, Shi-jie ZHOU, Renewable Energy School, North China Electric Power University, Beijing, China Corresponding author, Bing ZHANG, Renewable Energy School, North China Electric Power University, Beijing Key Laboratory of Energy Security and Clean Utilization, Beijing, China.