Unusual defect properties of the one-dimensional photovoltaic semiconductor selenium†

Abstract

Defect tolerance is crucial in photovoltaic absorbers. Here we report that trigonal selenium (t-Se) exhibits a perovskite-like antibonding valence band maximum arising from Se p–p coupling. This results in the shallow nature of dominant Se vacancy defects. We further reveal the unique defect self-healing characteristic of Se intrinsic point defects.