Efficient quasi-mesoscopic perovskite solar cells using Li-doped hierarchical TiO2 as scaffold of scattered distribution

Circular plate like lithium doped hierarchical TiO2 (Li-hier-TiO2) nanostructures were synthesized and scattered on the compact TiO2 layer as a quasi-scaffold layer for perovskite solar cells (PSCs). The quasi-scaffold layer provides superior contact properties with perovskite layer and helps to form the high quality perovskite film with better crystallinity and less pin-holes. Simultaneously, Li-hier-TiO2 quasi-scaffold compared to pure hier-TiO2 quasi-scaffold exhibits superior electronic properties due to the reduced trap states together with better electron transport and extraction abilities. PSCs using Li-hier-TiO2 quasi-scaffold layer to host the CH3NH3PbI3 photoactive layer produce substantially higher PCE of 18.25% with suppressed hysteretic behavior, which is obviously higher than PCE (15.64%) of PSCs using pure hier-TiO2 quasi-scaffold layer.