Heterojunction interface engineering enabling high onset potential in Sb2Se3/CdS photocathodes for efficient solar hydrogen production

Abstract

Sb2Se3 has emerged as an ideal photocathode candidate profiting from its superior optoelectronic properties, and has gained rapid development in photocurrent generation. However, achieving both high photocurrent density (Jph) and onset potential (Von) is of immense importance. In this work, self-assembled growth of Sb2Se3 with large crystal grains, benign orientation, and accurate composition was first fulfilled via a combination reaction involving sputtered and selenized Sb precursor. Then Mo/Sb2Se3/CdS/Pt photocathodes were constructed. In addition to the selenization condition-dependent Sb2Se3 film quality that influenced device performance, an additional Sb2Se3/CdS heterojunction post-annealing has demonstrated a strong positive effect. Thanks to the band alignment modification, charge transport strengthening, and surface wettability improvement, the champion device delivered Jph of 16.25 mA cm−2, Von of 0.52 VRHE, and HC-STH conversion efficiency of 2.58%. Such an interface engineering can pave the way for fabricating high Von Sb2Se3 photocathode to broaden its scope of solar hydrogen production applications.