Interfacial TiO2 atomic layer deposition triggers simultaneous crystallization control and band alignment for efficient CsPbIBr2 perovskite solar cell

We present that atomic layer deposition (ALD) of TiO2 thin layer on SnO2 electron transport layer (ETL) could simultaneously boost the crystallization control of CsPbIBr2 absorber film and band alignment of all-inorganic perovskite solar cell (PSC). The former awards the desired CsPbIBr2 film characterized by high crystallinity, weak halide phase separation, as well as extremely uniform-and large-sized grains. And, the latter brings a cascade pathway for electron extraction and transport in the cell. Such combined morphology tailoring and interface engineering are extremely beneficial to suppress both bulk recombination and interfacial recombination of charge carrier. As a result, the cell' efficiency can be boosted from 6.11% to 9.31%, which is beyond all the pure CsPbIBr2-based PSCs reported to date. Therefore, our works highlight the dual functions of ALD-processed TiO2 interfacial layer in processing high-performance all-inorganic PSC.