Unveiling the Role of Donor Polymer Antisolvent Additives in the Enhanced Performance and Stability of Carbon-Based Perovskite Solar Cells

Low-temperature, solution-processed carbon-based perovskite solar cells (c-PSCs) often suffer from surface defects and nonideal crystallization caused by rapid antisolvent quenching of MAPbI3. To this end, incorporating polymers as antisolvent additives offers a simple route to regulate crystallization and reduce interfacial defects. Here, four donor polymers─P3HT, PCE10, PM6, and PM7─are introduced during MAPbI3 deposition. Their distinct Highest Occupied Molecular Orbital (HOMO) energy levels enable us to probe how energetic alignment influences their interaction with MAPbI3 surfaces and their passivation capability. The additives are found to improve crystallinity, yielding larger grains and lower trap densities. In particular, PM7 provides the highest enhancements because its HOMO level lies closest to the MAPbI3 valence band, enabling more favorable interfacial passivation and more effective suppression of surface recombination. Consequently, PM7-treated films exhibit longer photocarrier lifetimes, lower ideality factors, reduced interfacial resistance, and smaller trap-filled limit voltages. Devices using PM7 reach a PCE of 14.6%, a 53.8% improvement over the control. Overall, this study demonstrates that the HOMO level of antisolvent additives is a decisive factor governing interfacial interactions and enhancing MAPbI3 passivation.