Tetrahydrofuran as an Oxygen Donor Additive to Enhance Stability and Reproducibility of Perovskite Solar Cells Fabricated in High Relative Humidity (50%) Atmosphere

摘要： In sequential deposition method of lead-halide perovskite material, the PbI2 layer morphology plays an essential role in enhancing the power conversion efficiency (PCE) of the perovskite solar cell. However, humidity level affects the PbI2 and perovskite film morphology, resulting in defect sites and recombination centers on the surface and within the bulk of the perovskite solar cell. To address this, we report the incorporation of tetrahydrofuran (THF) additive in PbI2-DMF precursor solution, to improve the quality of PbI2 thin film and to prevent the water interaction directly with PbI2 under high humidity environment. The O-donor THF interacts with PbI2 resulting in the homogeneous, dense and pinhole-free layer as compared to PbI2 layer without additive. The Perovskite layer so obtained from pinhole-free PbI2 layer is compact and smooth resulting in a significant reduction of defects/traps. The device fabricated with modified perovskite ~ 50% humidity atmosphere, resulted in 15% efficiency with high reproducibility. Moreover, the THF modified non-encapsulated perovskite device retains its 80% PCE after exposing to 50% relative humidity for 20 days. Our result demonstrates the strategy to fabricate perovskite solar cells with reproducible efficiency in high humidity atmosphere viable for large-scale production.