Conformation Tailoring of Diphenylfluorene‐Cored Isomers as Hole‐Transport Materials for Perovskite Solar Cells

The fine structural–functional construction of organic semiconductor materials provides an abundant candidate store for the hole‐transport materials (HTMs) in perovskite solar cells (PSCs). Whereas, challenges remain in unveiling the clews behind the molecular conformation engineering and desired properties realizing for efficient HTMs. In this work, a couple of simple organic diphenylfluorene‐cored isomers (FH27 and FH99) with different spatial integration strategies of molecular conformation are judiciously devised as HTMs in the PSCs. The theoretical simulation and experimental analyses decipher that the excellent electronic/energetic distribution, intermolecular stacking geometry, intrinsic solid‐crystal film morphology, and charge‐extraction‐transport ability are demonstrated for FH27, ascribing to its harmonious intersectional couplings for the planar/orthogonal molecular conformation. The FH27‐based device achieves a high efficiency of 23.61% with benign life span, both superior to the FH99‐based device.