Low temperature plasma enhanced atomic layer deposition of tin oxide electron selective layers for highly efficient planar perovskite solar cells
Recent progress has shown that low temperature processed tin oxide (SnO2) is an excellent electron selective layer (ESL) material for fabricating highly efficient organic inorganic metal halide perovskite solar cells with a planar cell structure. Low temperature processing and a planar cell structure are desirable characteristics for large scale device manufacturing due to their associated low costs and processing simplicity. Here, we report that plasma enhanced atomic layer deposition (PEALD) is able to lower the deposition temperature of SnO2 ESLs to below 100 degC and still achieve high device performance. With C60 self assembled monolayer passivation, our PEALD SnO2 ESLs deposited at ~100 degC led to average power conversion efficiencies higher than 18% (maximum of 19.03% and 15% (maximum of 16.80% under reverse voltage scan for solar cells fabricated on glass and flexible polymer substrates, respectively. Our results thus demonstrate the potential of the low temperature PEALD process of SnO2 ESLs for large scale manufacturing of efficient perovskite solar cells.