Mechanochemical Synthesis of the Lead-Free Double Perovskite Cs2[AgIn]Br6 and its Optical Properties

TL;DR

This paper reports the successful mechanochemical synthesis of a lead-free double perovskite, Cs2[AgIn]Br6, and investigates its structural and optical properties, highlighting challenges like instability under illumination for photovoltaic applications.

Contribution

It introduces a novel mechanochemical synthesis method for Cs2[AgIn]Br6 and provides detailed analysis of its structure and optical properties, advancing lead-free perovskite research.

Findings

Crystallizes in an elpasolite-type structure with a = 11.00 Å

Optical bandgap of 2.36 eV identified

Unstable under illumination, limiting photovoltaic use

Abstract

Hitting hard on the binary halides yields in the formation of Cs2[AgIn]Br6. The lead-free double perovskite marks, although not usable itself, a further step forward in finding sustainable and durable perovskite materials for photovoltaic applications. Cs2[AgIn]Br6 is one of the prominent examples of double perovskites materials that have been suggested to circumvent the use of lead compounds in perovskite solar cells. We herein report the successful synthesis of the material using a mechanochemical approach. It crystallizes in an elpasolite-type structure, an ordered perovskite superstructure, with a cell parameter of a = 11.00 {\AA}. However, the compound exhibits a relatively large optical bandgap of 2.36 eV and is unstable under illumination, which impedes its use as solar absorber material at this early stage. Still, substitution of lead and the potential of this synthesis method are promising as well as the fruitful combination of theoretical considerations with experimental materials discovery.