4-Tert butylpyridine induced MAPbI ₃ 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 CH ₃ NH ₃ I solution for improving the CH ₃ NH ₃ PbI ₃ film quality fabricated with two-step deposition method. Due to the strong polarity and interaction between N atom on TBP and Pb atom on CH ₃ NH ₃ PbI ₃ , this strategy leads to a substantial enhancement of the CH ₃ NH ₃ PbI ₃ film quality with larger grains, higher crystallinity and more complete coverage on the substrate than that of the pristine one. Thereby, the TBP-based CH ₃ NH ₃ PbI ₃ 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.