Ethylammonium as an alternative cation for efficient perovskite solar cells from first-principles calculations

Abstract

Mixed-cation lead halide perovskites have emerged as a new class of promising photovoltaic materials for perovskite solar cells. Formamidinium (FA), methylammonium (MA), and Cs cations are widely studied in the field of mixed-cation hybrid halide perovskites. In this work, we have investigated ethylammonium (CH3CH2NH3, EA) as an alternative cation to explore the stabilities and electronic properties of mixed MA1-xEAxPbI3 perovskites. The results indicate that replacing MA with EA is a more effective way to improve the stabilities of the mixed MA1-xEAxPbI3 perovskites except for MA0.75EA0.25PbI3. The band gap of MA1-xEAxPbI3 slightly increases with x from 0.25 to 1.00, which is quite different from the MA-FA mixed-cation perovskites. The results indicate that the c axis distortion of the Pb-I-Pb bond angles can play a greater role in tuning the band gap. Moreover, the mixed MA1-xEAxPbI3 perovskites show comparable absorption abilities in the visible light region to the pure MAPbI3 structure. We hope that our study will be greatly helpful for further experiments to find more efficient perovskite materials in the future.