The interfacial or bulk defects of the perovskite layer are important factors that affect the stability and photoelectric conversion efficiency of perovskite solar cells (PSCs). Herein, a multifunctional amino alcohol, 2,2‐Bis (3‐amino‐4‐hydroxyphenyl) hexafluoro propane (BHF), C15H12F6N2O2, is used as an additive of the active layer in p–i–n organic–inorganic halide perovskite solar cells. The BHF additive passivates perovskite predominately at grain boundaries. This additive leads to a vertically aligned crystal grain and reduced defect densities. The BHF‐treated perovskite films show suppressed nonradiative recombination with enhanced photoluminescence, longer carrier lifetimes, and reduced ionic migration. The device doped with 1 mg mL−1 BHF is able to improve power conversion efficiency to 20.30% (from 16.83% of the control), mainly due to the improvement of open‐circuit voltage. In addition, BHF passivation generates a more stable perovskite structure, resulting in improved operational stability of the PSCs.