Prospects of copper–bismuth chalcogenide absorbers for photovoltaics and photoelectrocatalysis

Abstract

Wittichenite, Cu₃BiS₃ (CBS), is perceived as an appealing material for application as a photoabsorber due to its ns² electronic configuration and antibonding character on its upper valence band, which provides defect-tolerance characteristics. Herein, we highlight the high charge carrier mobility and low effective mass due to the high dispersive character of both the valence and conduction bands in CBS. The absorption coefficient of CBS is as high as >10⁵ cm⁻¹ (energy > 1.43 eV); however, it is still poorly explored in photovoltaic (PV) (maximum power conversion efficiency of 1.7%) and photoelectrochemical (PEC) devices. The challenges and questions related to the nature of the bandgap, intrinsic defects, and charge transport in CBS need to be addressed to enhance its PV and PEC performance. In this review, we provide an overview of the crystal and energetic structure, optoelectronic properties, recent advances in synthesis methods, and experimental realization of devices based on CBS. Further, we outline the important research directions that are indispensable for the development of CBS-based devices.