New Benzotrithiophene‐Based Hole‐Transporting Materials for Perovskite Solar Cells: Succinct Synthesis and PCE Improvement

Abstract We report a succinct synthesis of benzotrithiophene ( BTT ) core‐based new hole‐transporting materials (HTMs) with t ‐butyl terminal substituents, using boron‐ and tin‐free threefold direct C−H/C−Br couplings as key transformations. One of the synthesized oligoaryls ( YKP05 ) incorporating additional 3,4‐ethylenedioxythiophene (EDOT) moiety as π‐spacers displayed significantly improved power conversion efficiency of up to 15.1 % while fabricated in perovskite solar cells as hole‐transporting layer.