Improving self-assembly behavior and photovoltaic performance of the indacenodithiophene-based small molecules via increasing dipole moment of the terminal group

Two novel photovoltaic small molecular donors of IDT(BT-T3Cz)2 and IDT(DFBT- T3Cz)2, with a D(A-Ar)2 framework were prepared. Both SMs exhibit well molecular packing and self-assembly behavior. The best photovoltaic performance with a PCE of 5.99% was obtained in the IDT(DFBT-T3Cz)2 based solar cells with a high FF up to 59.6%.266