Hole‐Transporting Materials based on Oligo(hetero)aryls with a Naphthodithiophene Core – Succinct Synthesis by Twofold Direct C−H Olefination

This work demonstrated the first synthetic application of direct C−H olefinations in the step‐saving preparation of various hole‐transporting materials (HTM) for efficient perovskite solar cells (PSC). Cross‐dehydrogenative couplings of naphthodithiophene (NDT) with vinyl arenes under palladium‐catalysis facilely generated various new oligo(hetero)aryls with internal alkenes. Reaction conditions were optimized, which gave the product isolated yields of up to 71 % with high (E)‐stereoselectivity. These readily accessible NDT core‐based small molecules involving olefin as π‐spacers displayed immediate power conversion efficiencies of up to 17.2 % without a device oxidation process that is required for the commercially available spiro‐OMeTAD and most other existing HTMs while fabricated in corresponding PSC devices. For the first time, C−H/C−H cross‐dehydrogenative couplings (direct C−H olefinations) are used as key step to access small‐molecule hole‐transporting materials (HTMs). NDT core‐based HTMs incorporating additional olefins as π‐spacers substantially improve the PCE of perovskite solar cells of up to 17.2 %.