Efficient and Stable Inverted Perovskite Solar Cell using Potassium Fluoroborate Doped PEDOT:PSS

Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is widely used as a hole transport layer in inverted perovskite solar cells (PSCs) due to its simple fabrication process and high stability. However, there are severe interface defects between PEDOT:PSS and the perovskite layer, leading to poor power conversion efficiency (PCE) of the inverted devices. Herein, a hole transport layer (PEDOT:PSS) doped with potassium fluoroborate is introduced. The aqueous solution of KBF 4 diluted with PEDOT:PSS is cleverly utilized to compare with PEDOT:PSS diluted with deionized aqueous solution. X‐ray photoelectron spectroscopy of PEDOT:PSS confirms the reduction of PSS chains and an increase in conductivity after KBF 4 doping. Moreover, KBF 4 doping promotes crystal growth, resulting in larger grain size of the perovskite film. Additionally, the defects at the PEDOT:PSS/perovskite interface are effectively passivated, suppressing nonradiative recombination. The results show improved short‐circuit current density, open‐circuit voltage, and fill factor, resulting in a PCE of 19.76%, which is a 17.9% enhancement compared to the original device's 16.75%. The optimized device also exhibits long‐term stability exceeding 1000 h, providing a simple and effective strategy for improving the PCE and stability of inverted PSCs.