Sulfur Treatment Passivates Bulk Defects in Sb ₂ Se ₃ Photocathodes for Water Splitting

Abstract

Abstract Sb 2 Se 3 has emerged as an important photoelectrochemical (PEC) and photovoltaic (PV) material due to its rapid rise in photoconversion efficiencies. However, Sb 2 Se 3 has a complex defect chemistry, which reduces the maximum photovoltage. Thus, it is important to understand these defects and develop defect passivation strategies in Sb 2 Se 3 . A comprehensive investigation of the charge carrier dynamics of Sb 2 Se 3 and the influence of sulfur treatment on its optoelectronic properties is performed using time‐resolved microwave conductivity (TRMC), photoluminescence (PL) spectroscopy, and low‐frequency Raman spectroscopy (LFR). The key finding in this work is that upon sulfur treatment of Sb 2 Se 3 , the carrier lifetime is increased by the passivation of deep defects in Sb 2 Se 3 in both the surface region and the bulk, which is evidenced by increased charge carrier lifetime of TRMC decay dynamics, increased radiative recombination efficiency, decreased deep defect level emission (PL), and the emergence of new vibration modes by LFR.