High-Efficiency Planar Hybrid Perovskite Solar Cells Using Indium Sulfide as Electron Transport Layer

For a high-performance perovskite solar cell (PSC), the electron transport layer (ETL) plays a prominent role in the transportation of photogenerated charge carriers from the perovskite layer to electrode. Herein, indium sulfide (In2S3) nanosheets are synthesized by solvent-thermal method; In2S3 ETL is prepared by spin-spraying technique, and planar PSC is thus fabricated. The morphology observation indicates that the as-prepared In2S3 ETL is compact, smooth, pinhole-free, and with an optimal thickness of 40 nm. The photoelectrical characterization reveals that, compared to TiO2 ETL, the In2S3 ETL has lower electron trap-state density, lower potential barrier for electron injection from the perovskite layer, higher electron mobility and electron extraction ratio at the In2S3/perovskite interface, smaller contact resistance, and charge recombination. The planar device fabricated with CH3NH3PbI3 perovskite and In2S3 ETL gains an impressive power conversion efficiency (PCE) of 18.83%, and the photovoltaic device with TiO2 ETL obtains a PCE of 15.88% under the same experimental condition. The results provide a novel, low-cost, efficient, and alternative ETL material for PSCs.