Designing Double Perovskites with Organic Dications for Enhancing Stability and Photoelectrical Performance

Abstract

Recently, the research on developing lead‐free double‐B‐cation halide perovskites has attracted attention. However, Cs2InBiCl6, the most promising one, was shown to be thermodynamically unstable. To improve the stability, organic dication DiMA2+ (i. e., (CH2NH3)+(CH2)3(CH2NH3)+) is introduced to design the new double perovskite DiMAInBiX6 (X=Cl, Br, and I) based on Cs2InBiX6 by replacing two Cs+ with a DiMA2+. Density functional theory calculations were performed to study the geometric and photoelectric properties of the newly designed materials. Unlike Cs2InBiX6, both DiMAInBiCl6 and DiMAInBiBr6 can exist stably against decompositions, indicating that the replacement of Cs+ by DiMA2+ will improve stability of double perovskites due to the staple effect. In addition, the replacement causes an increase in the band gaps of DiMAInBiX6. Particularly, the calculated band gap of DiMAInBiBr6 (1.31 eV) is close to the optimal value of single junction perovskite solar cell (PSC). Under ideal conditions, the PSC model constructed with DiMAInBiBr6 performs the best in theoretical simulation. This work proposes DiMAInBiBr6 as a promising light absorber of PSC, which has high stability and photoelectric performance. It also suggests that the replacement of Cs+ by DiMA2+ may serve as a rational and practical way to design new organic‐inorganic hybrid double perovskites.