Parallel Exploration of the Optoelectronic Properties of (Sb,Bi)(S,Se)(Br,I) Chalcohalides

TL;DR

This study explores the optoelectronic properties of (Sb,Bi)(S,Se)(Br,I) chalcohalides, synthesizing eight compounds and analyzing their carrier dynamics, phonon interactions, and defect structures to guide material optimization for solar energy devices.

Contribution

It introduces a scalable synthesis method and comprehensive analysis of structure-property relations in chalcohalides, advancing their potential for optoelectronic applications.

Findings

Bandgaps from 1.38 to 2.08 eV with sharp PL peaks

Carrier dynamics and electron-phonon interactions significantly affect performance

Solid-solution engineering can tune phonon structures and reduce non-radiative recombination

Abstract

Chalcohalides are an emerging family of semiconductors with irresistible material properties, shaped by the intricate interplay between their unique structural chemistry and vibrational dynamics. Despite their promise for next-generation solar energy conversion devices, their intrinsic optoelectronic properties remain largely unexplored. Here, we focus on the (Sb,Bi)(S,Se)(Br,I) system, a subset of compounds that share the same quasi-1D crystal structure. Using a two-step physical vapor deposition (PVD) process, we synthesize the eight ternary chalcohalide compounds, demonstrating bandgaps ranging from 1.38 to 2.08 eV with sharp, single-component photoluminescence (PL) peaks. In a parallel exploration of carrier dynamics and intrinsic electron-phonon interactions -- comprehensively studied using power-, temperature-dependent, and time-resolved PL measurements -- we map their direct impact on optoelectronic performance. Supported by first-principles density functional theory (DFT) defect calculations, we establish clear structure-property relations, identifying solid-solutions engineering as an effective means to fine-tune the native phonon structures and further suppress non-radiative recombination. This study provides a blueprint for optimizing chalcohalides as high-efficiency materials across a wide range of optoelectronic applications.