Microstructural analysis and optical properties of Cs2BiAgBr6 halide double perovskite single crystals

TL;DR

This study investigates the microstructure and optical properties of Cs2BiAgBr6, a lead-free double perovskite, revealing its cubic structure, indirect band gap, and photoluminescence characteristics through experimental and computational methods.

Contribution

The paper provides detailed structural and optical characterization of Cs2BiAgBr6 single crystals, combining experimental crystallography with DFT calculations to elucidate its electronic properties.

Findings

Cs2BiAgBr6 has cubic Fm-3m symmetry with a = 11.20 Å.

The material is an indirect band gap semiconductor.

Photoluminescence spectra show three broad bands related to band transitions.

Abstract

Single crystals of Cs2BiAgBr6 lead-free perovskite were grown by crystallization from supersaturated solution. According to characterization by XRD and EBSD methods the double perovskite single crystal are of the cubic Fm-3m symmetry with the lattice constant a = 11.20 {\AA}. DFT predictions based on the single crystal X-ray diffraction analysis reveal that the material is an indirect band gap semiconductor. Low temperature (1.4 K) photoluminescence spectra demonstrate three broadened bands that correspond to two lowest computed indirect and one direct band-to-band transitions.