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

摘要

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 (CH _(3) CH _(2) NH _(3) , EA) as an alternative cation to explore the stabilities and electronic properties of mixed MA _(1? x ) EA _( x ) PbI _(3) perovskites. The results indicate that replacing MA with EA is a more effective way to improve the stabilities of the mixed MA _(1? x ) EA _( x ) PbI _(3) perovskites except for MA _(0.75) EA _(0.25) PbI _(3) . The band gap of MA _(1- x ) EA _( x ) PbI _(3) 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 MA _(1? x ) EA _( x ) PbI _(3) perovskites show comparable absorption abilities in the visible light region to the pure MAPbI _(3) structure. We hope that our study will be greatly helpful for further experiments to find more efficient perovskite materials in the future.