Dual-Functional Optimization via Cyano-Functionalized Fullerene Reconstruction and Hot-Pressing Treatment for Enhanced Performance of Carbon-Based Perovskite Solar Cells

This study presents a dual-functional interfacial engineering strategy that integrates chemical modification with hot-pressing treatment to significantly enhance the efficiency and stability of carbon-based perovskite solar cells (C-PSCs). Through rational molecular design, a novel fullerene derivative, C₆₀-CN, was synthesized via the Prato reaction by introducing a cyano (-C≡N) functional group and enables simultaneous SnO₂ electron transport layer (ETL) reconstruction and perovskite crystallization guidance. Experimental results demonstrate that the incorporation of C₆₀-CN effectively alleviates oxygen vacancies in SnO₂ while increasing surface roughness, which improves the contact quality of perovskite films and enhances charge extraction efficiency. Moreover, the hot-pressing process optimizes the interfacial contact characteristics between the perovskite layer and the carbon electrode, promoting the recrystallization of the perovskite material and reducing defect density. As a result of these optimizations, the device achieved a power conversion efficiency (PCE) of 15.78%, representing a 29.34% improvement compared to the original device (from 12.20% to 15.78%). The enhanced stability can be attributed to the suppression of ion migration, the reduction of nonradiative recombination losses, and the improvement of the hydrophobic properties of the perovskite layer. Key mechanisms include Sn-N synergies at the SnO₂/C₆₀-CN interface for defect passivation, as well as the recrystallization and densification effects induced by hot-pressing on the perovskite material. These findings highlight the feasibility of fabricating high-performance, low-cost perovskite solar cells at room temperature through the combination of chemical modification and physical treatment strategies.