Sputtered Ga-Doped SnO_x Electron Transport Layer for Large-Area All-Inorganic Perovskite Solar Cells

The scalability processing of all functional layers in perovskite solar cells (PSCs) is one of the critical challenges in the commercialization of perovskite photovoltaic technology. In response to this issue, a large-area and high-quality gallium-doped tin oxide (Ga-SnOx) thin film is deposited by direct current magnetron sputtering and applied in CsPbBr3 all-inorganic PSCs as an electron transport layer (ETL). It is found that oxygen defects of SnOx can be remarkably offset by regulating oxygen flux and acceptor-like Ga doping level, resulting in higher carrier mobility and suitable energy level alignment, which is beneficial in accelerating electron extraction and suppressing charge recombination at the perovskite/ETL interface. At the optimal O2 flux (12 sccm) and Ga doping level (5%), the device based on sputtered Ga-SnOx ETL without any interface modification shows a power conversion efficiency (PCE) of 8.13%, which is significantly higher than that of undoped SnOx prepared by sputtering or spin coating. Furthermore, a PCE of 5.98% for a device with an active area of 1 cm2 is obtained, demonstrating great potential in fabricating efficient and stable large-area PSCs.