Carbon-based perovskite solar cells (C-PSCs) have attracted significant interest for their advantages of high photoelectric conversion efficiency (PCE), long-term stability and low cost, showing superiority in commercialization of perovskite solar cells (PSCs). However, the promoting effect of PbTiO₃ modification and polarization treatment on C-PSCs photovoltaic performance by in-situ generation of PbTiO₃ on a dense electron transport layer of TiO₂ (c-TiO₂) is still unknow.. It was found that the PbTiO₃ formed after reaction for 30 s could effectively restrict the sharp increase in resistance of the electron transport layer, and substantially reduced the carrier accumulation at the interface to 29.7%, greatly improving the carrier separation ability. In addition, the carrier accumulation was further reduced to 6.78% through polarizing the c-TiO₂/PbTiO₃ layer, so that PSCs displayed 0.93 V of open circuit voltage (V_oc), 14.83 mA/cm² of short circuit current density (J_sc), 51.16% of fill factor (FF), and 7.11% of PCE. This work comprehensively reports the methods of PbTiO₃ modification and polarization treatment, proposes a research strategy to improve the performance of C-PSCs, reveals the intrinsic mechanism for optimizing carrier transport performance, and provides a way for developing high-efficiency, low-cost and long-life commercial PSCs.