Defects in solution-processed organic and inorganic halide perovskite thin films deteriorate their photovoltaic performance and stability. Here, a bisimidazole-based organic small molecular hole transport material (HTM) that can suppress interfacial defects of the perovskite with its functional groups working as Lewis bases is newly introduced. Surface passivation of perovskite film leads to the reduction in non-radiative recombination trap density as well as the improvement of its crystallinity, consequently enhancing the efficiency of perovskite solar cell (PSC) from 16.3% to 18.3% with superior stability, preserving 92% of its initial efficiency for 500 h in an atmosphere.