Enhanced proton irradiation resistance in Cs-doped CH3NH3PbI3 films and solar cells

Abstract

Mixed-cation perovskite solar cells have attracted tremendous attention in space applications due to their excellent power conversion efficiency (PCE) and stability to light and heat. Although the evolution of photovoltaic performance in different space environments has been investigated, the role of inorganic cesium ions (Cs+) in the enhancement of irradiation resistance needs to be further clarified. Herein, the structure and performance evolution of Cs-doped CH3NH3PbI3 (MAPbI3) films and planar heterojunction devices under proton irradiation up to 1 × 1016 p cm−2 were studied. 5% of Cs+ doping can increase the cohesive energy of MAPbI3 and effectively alleviate the lattice strain induced by proton irradiation, thereby enhancing the crystallinity and stability of films. The bandgap changes of irradiated Cs0.05MA0.95PbI3 films under the identical fluence were only one third of that of MAPbI3 films. Upon irradiation under the fluence of 1 × 1014 p cm−2, the density of trap states in the undoped and 5%Cs-doped films increased by 71% and 9%, respectively, and the average PCE of 20 corresponding devices decreased only by 12% and 9%, respectively. This proves that the replacement of organic methylamine ion with inorganic cesium ion contributes to the improvement of MAPbI3 resistance to proton irradiation, thus confirming the application prospects of mixed-cation or all-inorganic perovskite solar cells in spacecraft.