Dendritic growth lowers carbon electrode work function for efficient perovskite solar cells

A major challenge in the development of printable mesoscopic perovskite solar cells (p-MPSCs) is the modification of the carbon electrode's work function to facilitate holes extraction and transport in carbon-based hole transport layer (HTL)-free devices. To address this, we present an innovative approach: in-situ polymerization of aniline on nano-graphite's surface, followed by carbonization, forming a dendritic structure. The modified carbon electrode exhibits reduced work function from −5.06 eV to −5.19 eV and improved energy level alignment with perovskite, facilitating charge collection and significantly enhancing hole collection. This results in a photovoltaic conversion efficiency increase from 15.16 % to 18.19 % in p-MPSCs. Furthermore, the modified carbon electrode-based p-MPSCs exhibit exceptional stability, maintaining high power conversion efficiency even after 10,000-h air exposure without encapsulation. Our work presents a vital strategy for improving photovoltaic conversion characteristics and stability of p-MPSCs through carbon electrode interface modification.