New Fused Bis-Thienobenzothienothiophene Copolymers and Their Use in Organic Solar Cells and Transistors

Abstract

A new tetradodecyl-substituted DTBTBT donor unit is synthesized by a specific bis-annulation via Suzuki–Miyaura coupling and successfully incorporated into light absorbing electron donor copolymers for OPV and hole and electron transport OFET polymer devices. All copolymers (DTBTBT-<i>co</i>-benzothiadiazole (Bz), DTBTBT-<i>co</i>-thiophene (T) and DTBTBT-<i>co</i>-thienothiophene (TT)) show fully coplanar backbones and strong intermolecular interactions. The DTBTBT-Bz copolymer led to a deep HOMO level (−5.2 eV) and thus a large <i>V</i>_oc value of 0.92 V with PC₇₁BM as electron acceptor and a PCE of 3.7% with a <i>J</i>_sc of 6.78 mA/cm² could be obtained. A hole mobility of 0.1 cm²/(V s) has been observed for the highly coplanar and more crystalline DTBTBT-T copolymer