Sarah Youn1,2,Jihyun Kim1,Junhong Na3,William Jo1,Gee Yeong Kim2
Ewha Womans University1,Korea Institute of Science and Technology2,Kyungnam University3
Sarah Youn1,2,Jihyun Kim1,Junhong Na3,William Jo1,Gee Yeong Kim2
Ewha Womans University1,Korea Institute of Science and Technology2,Kyungnam University3
Perovskite solar cells (PSCs) have shown outstanding performance during the past decade. An important parameter that controls device performance is the charge transport properties at interfaces. Tin oxide (SnO<sub>2</sub>) is a widely used electron transport layer (ETL) material in highly efficient perovskite solar cells owing to its superior electrical and optical properties. Therefore, understanding the interfacial effect of ITO/SnO<sub>2</sub> and its role in PSCs is crucial but it is not intensively studied. Here, we employ conductive atomic force microscopy and transfer length method as a function of SnO<sub>2</sub> thickness to identify space-charge effect at the interface. The results show that the critical kink point exists at about 10 nm of SnO<sub>2</sub> thickness, indicating electron depletion and expecting weak charge transfer behavior of the device. A thickness less than 20 nm was favorable for the best PSC performance because charge transport behaviors in the thin SnO<sub>2</sub> layer were modified by electron depletion. This study provides a strategy to tune the electron transport layer and boost the charge transport behavior in PSCs, making important contributions to optimizing SnO<sub>2</sub>-based PSCs.