Enhanced performance of carbon-based perovskite solar cells with a Li+-doped SnO2 electron transport layer and Al2O3 scaffold layer

SnO 2 (Tin oxide) is one of the most successful electron transport layer (ETL) materials in perovskite solar cells (PSCs) because of its low sintering temperature and simple preparation process. Similarly, carbon-based hole transport material-free PSCs (C-PSCs) have been widely studied because of their excellent stability and low price. Therefore, C-PSCs having SnO 2 as ETL can be envisaged as a promising PSCs system for commercial flexible equipment. However, studies on this system are still scarce because of its low power conversion efficiency (PCE). In this paper, the electron lifetime and current (J sc ) of a PSC containing a Li-SnO 2 /Al 2 O 3  + CH 3 NH 3 PbI 3 /carbon structure are greatly improved by doping lithium into SnO 2 (Li-SnO 2 ) and sandwiching an Al 2 O 3 interlayer into the Li-SnO 2 ETL and CH 3 NH 3 PbI 3 . A PCE of 10.01% is obtained, which is 42.3% higher than a PSC having a SnO 2 /CH 3 NH 3 PbI 3 /carbon structure. The entire preparation process is very simple and is carried out in an air atmosphere below 200 °C (20–40% humidity).