Novel D(A-Ar) 2 type small molecules with oligothiophene, diketopyrrolopyrrole and benzo[4,5]thieno [2,3- b ]indole units: investigation on relationship between structure and property for organic solar cells

Two novel D(A-Ar)2 type small molecules (SMs) of 3T(DPP-BTI)2 and 4T(DPP-BTI)2 were synthesized and characterized, which contain diketopyrrolopyrrole (DPP) arms, 6-dodecyl-6H-benzo[4,5]thieno[2,3-b]indole (BTI) terminals, and oligomerthiophene donor unit (3T=trithiophene, 4T=tetrathiophene). The relation-ship between structure and property was investigated. Compared with their corresponding parent A-D-A type SMs, both D(A-Ar)2 type SMs exhibited...