Enhancing performances of inverted perovskite solar cells by modifying the buried interface with sodium copper chlorophyllin

Defects at the buried interface and poor contact between the hole transport layer (HTL) poly-triarylamines (PTAA) and the perovskite layer are key issues affecting the efficiency and long-term stability of inverted perovskite solar cells (PSCs). In this study, we introduce sodium copper chlorophyllin (SCC, a chlorophyll derivative) as a modification agent at the HTL/perovskite interface to address these issues. Attributed to hydrophilic carboxylate groups of SCC, the wettability of the PTAA film is enhanced, facilitating the formation of the high-quality perovskite film. Meanwhile, SCC can interact with uncoordinated Pb2+ to passivate defects of the perovskite film at the buried interface. As a result, the power conversion efficiency (PCE) of inverted PSCs with the SCC modification reaches to 22.37% (from 20.58%) based on MAPbI3, and to 24.06% (from 21.54%) based on FAPbI3, respectively. Moreover, the devices show excellent stability in air and under light irradiation. This work indicates that the natural chlorophyll derivative is a promising candidate for improving the buried interface of high-performance inverted PSCs.