Zhiyang Ju, Wenyan Zhao, Jionghua Wu, Hongshi Li, Yumin Liu, Wenying Jiang, Tiankai Zhang, Chuanjin Tian, Shaojian Fu, Chang-An Wang, Zhipeng Xie
Abstract The planar triple‐layer hole transport layer (HTL)‐free carbon‐based perovskite solar cells have the advantages of low cost and high stability, but their low efficiency hinders the commercialization process. Here, a dual regulation strategy for bulk defects and interface defects has been developed. After selecting dimethylamine (DMA) as the fixed cation and selecting the anion site (I − , Br − , Cl − , HCOO − ), an ionic liquid additive, DMAFo, was synthesized, achieving multiple functions such as energy level regulation, removal of residual PbI 2 at the buried interface, retarding crystallization through the intermediate phase DMAPbI (3−x) HCOO x , filling halide vacancy defects, and releasing residual stress. This effectively reduces energy loss during carrier transport and obtains higher‐quality perovskite films. Under the synergistic effect of DMA + and HCOO − , both bulk defects and interface defects in the perovskite film were simultaneously addressed. The device prepared using DMAFo as an additive achieved the best device efficiency of 20.77%, and after continuous maximum power point tracking for 1200 h, the device efficiency remained almost unchanged, demonstrating excellent operational stability.