Figure 1: Scheme and structure of perovskite solar cell.

(a) Device structure of the perovskite planar heterojunction solar cells and schematic illustration for the crosslinking of C60-SAM with silane-coupling agent. ET, electron transfer. (b) Cross-section SEM image of a typical perovskite device with doped crosslinked C60-SAM (CLCS) ETL and high-resolution transmission electron microscopy (TEM) image of the cross-section area of the doped CLCS ETL.