Cesium Acetate Passivation Enables Efficient Electrodeposited Wide-Bandgap Perovskite Solar Cells

Electrodeposited wide‑bandgap perovskite solar cells (ED‑WBG PSCs) are promising for low‑cost fabrication, yet their development has been mostly restricted to all‑inorganic compositions with power conversion efficiency (PCE) typically below 8%, limited by insufficient crystallization quality and severe interfacial recombination. In this work, we extend electrodeposition to organic-inorganic hybrid wide‑bandgap perovskites and propose a simple cesium acetate (CsAc) interfacial passivation strategy. The champion device achieves a PCE of 14.57%, a significant increase from 12.04% for the control, accompanied by simultaneous improvements in fill factor (FF), open-circuit voltage (VOC), and short-circuit current density (JSC). The CsAc-passivated device retains 83% of its initial PCE after 1008 h in N2, while the control device retains only 71%. Meanwhile, the CsAc-passivated devices also exhibit superior stability under ambient and thermal environments. These results show that Cs+ and Ac- synergistically passivate defects, where Ac- coordinates with undercoordinated Pb2+, while Cs+ fills A-site vacancies on the perovskite surface, suppressing nonradiative recombination and facilitating charge transport and collection. This strategy provides practical guidance for interfacial defect passivation in ED‑WBG PSCs and highlights the promise of electrodeposition for high-efficiency and stable WBG PSCs.