Unveiling the Optoelectronic Potential of Vacancy-Ordered Double Perovskites: A Computational Deep Dive

TL;DR

This study uses first-principles calculations to explore the electronic, optical, and polaronic properties of vacancy-ordered double perovskites, revealing their high stability and potential for optoelectronic applications.

Contribution

It provides a comprehensive computational analysis of Rb-based VODPs, highlighting their promising optoelectronic properties and stability, which were not previously detailed.

Findings

Bandgap ranges from 0.56 to 6.12 eV

Strong IR to UV light absorption observed

High polaron mobility for electrons

Abstract

Lead-free perovskite materials have emerged as key players in optoelectronics, showcasing exceptional optical and electronic properties, alongside being environmentally friendly and non-toxic elements. Recently, among studied perovskite materials, vacancy-ordered double perovskites (VODPs) stand out as a promising alternative. In this study, we captured the electronic, optical, excitonic, and polaronic properties of a series of VODPs with the chemical formula Rb$_{2}$BX$_{6}$ (B = Si, Ge, Sn, Pt; X = Cl, Br, I) using first-principles calculations. Our results indicate these materials exhibit high stability and notable electronic and optical properties. The calculated G$_{0}$W$_{0}$ bandgap values of these perovskites fall within the range of 0.56 to 6.12 eV. Optical properties indicate strong infra-red to ultraviolet light absorption across most of the systems. Additionally, an analysis of excitonic properties reveals low to moderate exciton-binding energies and variable exciton lifetimes, implying higher quantum yield and conversion efficiency. Furthermore, utilizing the Feynman polaron model, polaronic parameters are evaluated, and for the majority of systems, charge-separated polaronic states are less stable than bound excitons. Finally, an investigation of Polaronic mobility reveals high polaron mobility for electrons (3.33-85.11 cm$^{2}$V$^{-1}$s$^{-1}$) compared to previously reported Cs-based VODP materials. Overall, these findings highlight Rb-based VODPs as promising candidates for future optoelectronic applications.