Advances in Se Wide-Bandgap Photovoltaics and Te_xSe_1-x SWIR Photodiodes

Elemental selenium (Se), tellurium (Te), and their alloys (Te_xSe_1-x) have re-emerged over the past decade as a promising materials system for low-cost and sustainable thin-film optoelectronic devices. In particular, Se has become a promising material for wide bandgap photovoltaics (PVs), and Te_xSe_1-x has arisen as a high-performance thin-film option for infrared (IR) photodetectors. In this review, we focus on recent developments in Se PVs and Te_xSe_1-x short-wave IR (SWIR) photodiodes (PDs). We discuss the motivations for pursuing these materials, the fundamental properties, considerations for toxicity and sustainability, and the advances in materials science and device engineering. Finally, we discuss open challenges and underexplored opportunities for further development.