Decoding Circular Dichroism Contributions in Chiral Hybrid Perovskites

Abstract

Hybrid organic–inorganic perovskites (HOIPs) are promising materials in optoelectronics, particularly for photovoltaic applications, due to their tunable properties and ease of fabrication. Among them, chiral HOIPs are gaining attention for their unique chiroptical properties, by the incorporation of chiral organic molecules into their structure. Despite their potential, the relationship between chiral HOIP structures and their chiroptical properties, such as circular dichroism (CD) spectra, remains challenging to decrypt. This study introduces a simulation workflow based on Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) to model the CD spectrum of the chiral 2D perovskite encapsulating S-1-(3-bromophenyl)-ethylamine (S-(3Br-MBA)₂PbI₄). The approach combines ab-initio molecular dynamics (AIMD) with TD-DFT calculations evaluating the contributions on the whole chiral hybrid perovskite scaffold and those of the isolated ligands, allowing us to dissect the contributions to the CD spectrum of chiral ligands and of the metal-halide sublattice. Additionally, the absorption dissymmetry factor g_abs has been also computed finding good agreement with the experimental value.

This work provides valuable insights for the design of advanced chiroptoelectronic materials.