Narrow band-gap copolymers with two acceptors of benzo[1,2-c;3,4-c′]bis[1,2,5]thiadiazole and Benzo[c][1,2,5] thiadiazole: Synthesis, characteristics and application in field-effect transistors

• Two new copolymers were designed and synthesized.
• The backbone of P1 and P2 contains benzobisthiadiazole and benzothiadiazole.
• The siloxane-terminated hexyl side chain was attached to P2.
• The devices of P1 exhibited hole mobility up to 1.04 × 10−2 cm2V−1s−1.

A series of copolymers containing two acceptors (benzo[1,2-c;3,4-c′]bis[1,2,5] thiadiazole and benzo[c][1,2,5]thiadiazole are designed and synthesized. Two kinds of side chains (2-octyl-1-dodecyl chain and siloxane-terminated hexyl chain) are added to the copolymer backbone. Both polymers show very narrow band gaps of ∼1.0 eV. Bottom-gate and bottom-contact transistors based on the polymers are fabricated and exhibit p-type filed-effect behavior with hole mobility up to 1.04 × 10−2 cm2V−1s−1.

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