Structural, Electrical, and Optical Responses in Hybrid Perovskite Semiconductors: The Influence of Symmetry in Central Molecule Interactions

Abstract

Hybrid organic–inorganic lead halide perovskites (HOIPs) have recently attracted ever-increasing attention due to their usefulness in optoelectronic devices such as highly efficient solar cells. In this work, a first-principles theoretical study is performed to investigate the effect of the replacement of inorganic cesium cations by organic methylammonium and formamidinium cations on the structural, electrical, and optical properties of HOIPs. We showed that these replacements profoundly affect the cation–cation (Cs⁺, MA⁺, FA⁺–Pb²⁺) and cation–anion (Cs⁺, MA⁺, FA⁺–I⁻, Br⁻, Cl⁻) interactions in the structure of HOIPs. It was found that the symmetry/asymmetry of the distribution of central cation interactions influences the band structure (considering spin–orbit coupling), electron density, dielectric function, and optical absorption spectrum. Finally, it can be said that due to specific disorders in the distribution of interactions and subsequently the creation of specific energy levels, HOIPs have higher power conversion efficiency (PCE) in solar cells than pure inorganic perovskites.

Graphical Abstract