4-Tert butylpyridine induced MAPbI3 film quality enhancement for improving the photovoltaic performance of perovskite solar cells with two-step deposition route

As we known, high-efficiency of the solution-processed perovskite solar cells can be achieved by modulating the perovskite film quality. Here, the prevalent 4-tert-butylpyridine is firstly utilized as an additive of CH3NH3I solution for improving the CH3NH3PbI3 film quality fabricated with two-step deposition method. Due to the strong polarity and interaction between N atom on TBP and Pb atom on CH3NH3PbI3, this strategy leads to a substantial enhancement of the CH3NH3PbI3 film quality with larger grains, higher crystallinity and more complete coverage on the substrate than that of the pristine one. Thereby, the TBP-based CH3NH3PbI3 film simultaneously exhibits superior optical properties and surface hydrophobicity. By optimization, the perovskite solar cells fabricated with TBP addition at a volume ratio of 7/1000 (v/v, TBP/isopropanol) exhibits significant performance enhancement with a power conversion efficiency reaching 17.06%, while the pristine one merely obtains a lower value of 14.56%. More importantly, this type of cells also shows a desirable efficiency reproducibility and long-time stability in air atmosphere. In conclusion, our work demonstrates another meaningful application for the TBP additive and provides a facile and effective strategy for further improving the performance of perovskite solar cells.