Post‐Synthetic Silver Ion and Sulfurization Treatment for Enhanced Performance in Sb<sub>2</sub>Se<sub>3</sub> Water Splitting Photocathodes
Pardis Adams, Ramon Schnyder, Thomas Moehl, Jan Bühler, Ángel Labordet Álvarez, Mirjana Dimitrievska, Keith P. McKenna, Wooseok Yang, S. David Tilley
Abstract
Abstract In the past decade, antimony selenide (Sb 2 Se 3 ) has made significant progress as a solar energy conversion material. However, the photovoltage deficit continues to pose a challenge and is a major hurdle that must be overcome to reach its maximum solar conversion efficiency. In this study, various post‐synthetic treatments are employed, of which the combination of a solution phase silver nitrate treatment and sulfurization has shown to be the most effective approach to mitigate the photovoltage deficit in this Sb 2 Se 3 ‐based device. A significant enhancement in the photovoltage is observed after the treatments, as evident by the increase in the onset potential from 0.18 to 0.40 V versus reversible hydrogen electrode. Multiwavelength Raman shows that combining these two treatments removes amorphous Se and metallic Sb from the surface and yields a high‐quality surface layer of Sb 2 (S 1−x , Se x ) 3 on the bulk Sb 2 Se 3 photoabsorber layer. X‐ray photoelectron spectroscopy with depth profiling reveals extensive incorporation of silver into the film. Density functional theory calculations suggest that silver ions can intercalate between the [Sb 4 Se 6 ] n ribbons and remain in the Ag + state. This effective treatment combination brings the practicality of the Sb 2 Se 3 photocathode for water splitting one step closer to large‐scale applications.