Interlayer modification between the perovskite and charge transport layers is critical to minimize trap-assisted recombination losses and promote highly efficient and stable perovskite solar cells. However, the cost and complexity of most modification materials limit the rapid development of perovskite photovoltaic technology. In this study, we propose Tris(1-chloro-2-propyl) phosphate (TCPP) as a cost-effective and efficient solution for interfacial modification. Theoretical calculations and experimental results demonstrate that the P=O group in TCPP effectively passivate both deep energy level defects and shallow defects of perovskite. This interaction enhances crystallinity, leading to high-quality films and improved solar cell efficiencies, achieving up to 20.73%. Our work presents the potential of organic molecules constructed with P=O group for enhancing both the efficiency and stability of perovskite solar cells, paving the way for their commercial viability.