Additive and interface passivation dual synergetic strategy enables reduced voltage loss in wide-bandgap perovskite solar cells

Abstract

The open-circuit voltage (VOC) loss for wide-bandgap (WBG) perovskite solar cells (PSCs) is a significant obstacle to their further development. Herein, we introduce a dual approach involving mixed potassium thiocyanate and potassium chloride (KSCN+KCl) additives combined with 2-thiophene methylamine iodine (2-ThMAI) post-passivation strategy to mitigate VOC loss in WBG PSCs. In the mixed additives, KSCN can expand the grains and reduce the grain boundary, while KCl can inhibit the migration of halogen ions, effectively preventing phase segregation in WBG perovskites under the combination of both. However, due to the substantial energy level mismatch at the perovskite/electron transport layer (ETL) interface, suppressing phase segregation alone is insufficient to reduce the VOC loss. Therefore, introducing 2-ThMAI interface passivation could uniform spatial distribution of perovskite surface potential, promote energetic alignment at perovskite/electron transport layer interface, and further reduce the VOC loss. With these optimizations, the champion WBG PSCs achieved an enhanced VOC of 1.327 V and a promising power conversion efficiency (PCE) of 19.44 %. Additionally, these modified WBG PSCs retained 94 % of their initial efficiency after 500 hours of continuous light soaking at maximum power point tracking in ambient conditions.