Methylammonium lead halide perovskites (MAPbX3) as promising light absorbers have great potential in perovskite solar cells (PSCs) due to notable characteristics of optimal band gaps, long-range exciton diffusion lengths, high ab-sorption coefficients and simple solution approaches. To date, the highest power conversion efficiency (PCE) of 22.1% has been achieved in a typically sandwiched device architecture. PSCs are still facing some challenges, such as the TiO2/MAPbI3 heterojunction interface loss, hysteresis behavior and reproducibility. Hence, we systematically studied the independent role of 2-, 3- and 4-pyridinesulfonic acid (PA) self-assembled monolayers (SAMs) on perovskite crys-tallinity and illuminated the binding energies of the above-mentioned SAMs on TiO2 and perovskite surfaces for highly efficient PSCs with reduced TiO2/MAPbI3 heterojunction interface loss, negligible hysteresis and high reproducibility. Through use of the 4-PA SAMs, the PSC exhibits striking improvements to the reach the highest efficiency of 18.90%, which constitutes an enhancement of ∼20% compared to that of PA SAMs-unmodified PSC (14.65%). Our work high-lights the importance of SAMs dipolar interactions and binding energies of SAMs on TiO2 and perovskite surfaces at electron transporting layer (ETL)/perovskite interfaces and paves the way for further optimizing the performances of PSCs.