Band-Gap Control via Structural and Chemical Tuning of Transition Metal Perovskite Chalcogenides

TL;DR

This study introduces a new synthesis method for high-quality transition metal perovskite chalcogenides, demonstrating their tunable band gaps and promising optical properties for solar energy applications.

Contribution

It provides the first systematic experimental investigation of the optical properties of TMPCs, confirming their potential for optoelectronic and solar energy conversion uses.

Findings

High-quality TMPC samples synthesized via a novel solid-state process.

Room temperature photoluminescence shows direct band gaps around 1.5-2.1 eV.

Materials exhibit promising optical properties for solar energy conversion.

Abstract

Transition metal perovskite chalcogenides (TMPC) are a new class of semiconductor materials with broad tunability of physical properties due to their chemical and structural flexibility. Theoretical calculations show that band gaps of TMPCs are tunable from Far IR to UV spectrum. Amongst these materials, more than a handful of materials have energy gap and very high absorption coefficients, which are appropriate for optoelectronic applications, especially solar energy conversion. Despite several promising theoretical predictions, very little experimental studies on their physical properties are currently available, especially optical properties. We report a new synthetic route towards high quality bulk ceramic TMPCs and systematic study of three phases, SrZrS3 in two different room temperature stabilized phases and one of BaZrS3. All three materials were synthesized with a catalyzed solid-state reaction process in sealed ampoules. Structural and chemical characterizations establish high quality of the samples, which is confirmed by the intense room temperature photoluminescence (PL) spectra showing direct band gaps around 1.53eV, 2.13eV and 1.81eV respectively. The potential of these materials for solar energy conversion was evaluated by measurement of PL quantum efficiency and estimate of quasi Fermi level splitting.