The distinctive benefits of perovskite solar cells, such as their lightweight nature, high flexibility, and ease of deformation, have garnered significant interest. These characteristics make them well-suited for use in portable electronic devices. Nevertheless, a large efficiency gap still exists between laboratory-based small cells and industrial-oriented large-scale modules. One of the primary reasons for the efficiency losses is the limited adhesion at the brittle interface between the perovskite layer and hole transport layer. Herein, potassium acetate is selected to tailor the interface of perovskite/hole transport layer. The presence of potassium acetate between the perovskite layer and hole transport layer has the potential to enhance the p-type perovskite interface. The strengthening of the interface contact could be verified by the utilization of KPFM and DFT calculations. As a result, the charge separation is accelerated associated with the substantial enhancement in Voc from 1.118 V to 1.139 V and the power conversion efficiency of the solar cell has been enhanced, resulting in an increase from 23.76% to 24.81%. Additionally, the perovskite solar module exhibits little loss, with an efficiency of 21.13% with an aperture area of 29.0 cm2.