Effects of Molecular Structure on Intramolecular Charge Carrier Transport in Dithieno [3,2-b: 2,3-d] Pyrrole-Based Conjugated Copolymers

Intramolecular mobility of positive charge carriers in conjugated polymer films based on dithieno [2,3- b: 2  , 3  - d] pyrrole (DTP) is studied by time-resolved microwave conductivity (TRMC). A series of DTP homopolymer and copolymers combined with phenyl, 2, 2  -biphenyl, thiophene, 2, 2  -bithiophene, and 9, 9  -dioctylfluorene were synthesized by Suzuki-Miyaura and Yamamoto coupling reactions. Polymers containing DTP unit are reported to show high value of hole mobility measured by FET method, and this type of polymers is expected to have stable HOMO orbitals which are important for hole transportation. Among these copolymers, DTP coupled with 9, 9  -dioctylfluorene copolymer showed the highest charge carrier mobility as high as 1.7 cm 2/Vs, demonstrating an excellent electrical property on rigid copolymer backbones.