Fluorinated Pentafulvalene‐Fused Hole‐Transporting Material Enhances the Performance of Perovskite Solar Cells with Efficiency Exceeding 23%

Abstract

AbstractOrganic small molecular materials with coplanar π‐conjugated system as HTMs in perovskite solar cells (PSCs) have attracted considerable attention due to their high charge transport capability and thermal stability. Herein, three novel pentafulvalene‐fused derivatives with or without fluorine atoms incorporated (YSH‐oF and YSH‐mF and YSH‐H, respectively) are designed, synthesized, and applied as hole‐transporting materials (HTMs) in PSCs fabrication. The fluorinated HTMs, YSH‐oF and YSH‐mF, exhibited higher hole mobility and better charge extraction at the perovskite/HTM interface than non‐fluorinated one do, presumably due to the closer intermolecular π–π packing interactions. As a result, small‐area (0.09 cm2) PSCs made with YSH‐oF and YSH‐mF achieved an impressive power conversion efficiency (PCE) of 23.59% and 22.76% respectively, with negligible hysteresis, in contrast with the 20.57% for the YSH‐H‐based devices. Furthermore, for large‐area (1.00 cm2) devices, the PSCs employing YSH‐oF exhibited a PCE of 21.92%. Moreover, excellent long‐term device stability is demonstrated for PSCs with F‐substituted HTMs (YSH‐oF and YSH‐mF), presumably due to the higher hydrophobicity. This study shows the great potential of fluorinated pentafulvalene‐fused materials as low‐cost HTM for efficient and stable PSCs.