A Processing Route to Chalcogenide Perovskites Alloys with Tunable Band Gap via Anion Exchange

TL;DR

This paper presents a synthesis method for chalcogenide perovskite alloys with tunable band gaps via anion exchange, maintaining crystal structure and improving photoconductive properties, potentially advancing solar cell technology.

Contribution

It introduces a selenization process to produce stable BaZr(S,Se)3 alloys with tunable band gaps and enhanced optoelectronic properties, without altering the crystal structure.

Findings

Band gap tunable between 1.5 and 1.9 eV

Films exhibit 100x stronger photoconductive response

Stable perovskite structure in high selenium content

Abstract

We demonstrate synthesis of BaZr(S,Se)3 chalcogenide perovskite alloys by selenization of BaZrS3 thin films. The anion-exchange process produces films with tunable composition and band gap without changing the orthorhombic perovskite crystal structure or the film microstructure. The direct band gap is tunable between 1.5 and 1.9 eV. The alloy films made in this way feature 100x stronger photoconductive response and a lower density of extended defects, compared to alloy films made by direct growth. The perovskite structure is stable in high-selenium-content thin films with and without epitaxy. The manufacturing-compatible process of selenization in H2Se gas may spur the development of chalcogenide perovskite solar cell technology.