Asymmetric Small Molecule as Interface “Governor” for FAPbI<sub>3</sub> Perovskite Solar Cells
Yawei Miao, Mengde Zhai, Zhenxiao Zhao, Xingdong Ding, Ziyang Xia, Haoxin Wang, Linqin Wang, Cheng Chen, Ming Cheng
Abstract
Delicate interface modification is necessary for improving the photovoltaic performance of a perovskite solar cell (PSC). Herein, two asymmetric small molecules, termed BTD-DA and BTD-PA are designed and synthesized to govern the perovskite/Spiro-OMeTAD interface. The molecule BTD-PA featuring a donor–acceptor–acceptor (D-A-A′) configuration shows a larger molecule dipole and a better effect on defect passivation and energy level regulation through the strong interaction between the pyridine group in BTD-PA and the surficial uncoordinated Pb 2+ . Consequently, the PSCs based on the BTD-PA treatment harvest a champion power conversion efficiency (PCE) of 24.46% for a 0.09 cm 2 active area and 22.46% for the 1 cm 2 device. Moreover, the long-term stability of FAPbI 3 PSCs is also significantly improved because of the enhanced hydrophobicity and the inhibited phase transition of the FAPbI 3 film with BTD-PA treatment. Our research provides a new strategy for interfacial engineering to boost the PCE and stability of the FAPbI 3 PSCs.