LAUSR

Abstract Efficient hole transporting materials (HTMs) for perovskite solar cells (PrSCs) is highly desired in emerging solar cell technologies. Three HTMs comprising a coplanar porphyrin core with different substituted electron donating triarylamine (TAA) groups (coded as SGT-061, SGT-062, and SGT-063) were successfully developed and used as HTMs for PrSCs. The porphyrin-based HTMs with more bulky donor groups (SGT-062 and SGT-063) possess the larger dihedral angle between alkoxy-substituted phenyl ring and the donor TAA core, leading to the greater interference for the dense molecular arrangement and reducing the π-π stacking of HTM molecules. But SGT-061 with a less bulky donor enables a tight molecular arrangement to increase the π-π stacking between molecules. This renders SGT-061 to have a higher hole mobility than that of SGT-062 and SGT-063 HTMs with bigger donor groups. Moreover, the dynamic charge transfer process of perovskite/various HTM films was studied by time-resolved photoluminescence decay. And SGT-061 exhibited more efficient hole extraction ability than that of SGT-062 and SGT-063. This could be ascribed to better hole mobility and better co-facial π-π stacking between molecules. These results indicate that a less bulky electron donor unit is a preferred peripheral group for developing porphyrin based HTMs for efficient perovskite solar cells.