Passivation of Magnetron-Sputtered SnO2 Via Ammonium Paratungstate for Enhanced Open-Circuit Voltage in Perovskite Solar Cells

Abstract

Magnetron sputtering is a highly promising method for fabricating all functional layers in perovskite solar cells. However, magnetron-sputtered SnO₂ (sp-SnO₂) films exhibit high defect density, leading to lower open-circuit voltage (V_OC), fill factor (FF), and power conversion efficiency (PCE) compared to spin-coated films. Here, ammonium paratungstate (APT) is introduced on the surface of sp-SnO₂ to passivate defects. The APT modification effectively passivates nonstoichiometric oxygen defects, suppresses nonradiative recombination, and improves heterojunction contact. Consequently, APT-treated devices achieve significantly enhanced performance and stability, with a V_OC of 1.041 V, FF of 77.78%, PCE of 20.54%, and retention of 80.98% initial efficiency after 1440 h of natural aging. This work demonstrates that APT passivation of sp-SnO₂ enables high-performance PSCs and provides a straightforward solution to improve the performance of sp-SnO₂ electron transfer layer.