Manipulating SnO2 Growth for Efficient Electron Transport in Perovskite Solar Cells

Abstract Solution‐processed tin oxide (SnO 2 ) is ubiquitously used as the electron transport layer (ETL) in perovskite solar cells, while the main concerns related to the application of SnO 2 nanoparticles are the self‐aggregation potential and infeasible energy level adjustment, leading to inhomogeneous thin films and mismatched energy alignment with perovskite. Herein, a novel route is developed by adding a functional titanium diisopropoxide bis(acetylacetonate) (TiAcAc) molecule, comprising TiO 4 4– core, functional CO, and long alkene groups, into the SnO 2 nanoparticle solution, to optimize the electronic transfer property of SnO 2 for efficient perovskite solar cells. It is found that the TiO 4 4– can be used to tune the electronic property of the SnO 2 layer, and the long alkenes can act as a stabilizer to avoid the nanoparticle aggregation and electronic glue among the SnO 2 nanoparticles in the eventual nanoparticulate thin film, enhancing its homogeneity and conductivity. Furthermore, the residual CO groups on the ETL surface can strongly associate with the Pb 2+ and improve the interface intimacy between the ETL and perovskite. As a result, the efficiency of perovskite solar cells can be boosted from 18% to above 20% with significantly reduced hysteresis by employing SnO 2 ‐TiAcAc as electron transport layer, indicating a great potential for efficient perovskite solar cells.