High-performance asymmetric small molecular donor materials based on indenothiophene for solution-processed organic solar cells

Abstract

Abstract Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)2 and IT(2FBT-TT3Cz)2 with an indenothiophene (IT) central donor core, fluorinated benzothiadiazole (2FBT) as acceptor and 3-carbazole (Cz) unit as terminal group were designed and synthesized as the donor materials in organic solar cells (OSCs). The thermal, optical absorption, electrochemical property, hole–electron mobility, film morphology were thoroughly studied. Using PC71BM as an electron acceptor, without any additive and thermal annealing (TA) treatment, the IT(2FBT-T3Cz)2-based cells showed a promising power conversion efficiency (PCE) of 5.81% and the IT(2FBT-TT3Cz)2-based cells exhibited a PCE of 4.39%. Our results demonstrate that the IT-based asymmetric small molecules can be developed as a promising class of donor materials for high-performance OSCs.