Self-assembled hole-transporting material constructed by chlorination and conjugation strategies toward efficient organic solar cells

The moderate charge-transporting capability together with higher-lying energetic levels of self-assembling hole-transporting materials (SAMs) constrain the productive carrier extraction dynamics. To alleviate this issue, a synergetic chlorination and extended conjugation strategy is applied to explore a novel HTL, named 2Cl-TPA-CN-COOH. Indeed, the chlorinated head backbone would deepen the energetic level and strengthen the intramolecular push-pull effect, whereas the elongated conjugation unit would boost the carrier-transporting potential. Consequently, a champion power conversion efficiency (PCE) of 18.6% with upgraded stability is obtained in a 2Cl-TPA-CN-COOH cell. These results demonstrate a new insight of the molecular configuration of SAMs, which would contribute to the enhancements of performance and reliability in the OSC field. A synergetic chlorination and extended conjugation strategy is applied to explore a novel, self-assembled hole-transporting material (2Cl-TPA-CN-COOH) for its application in organic solar cells.