Polymers based on thieno[3,4- c]pyrrole-4,6-dione and pyromellitic diimide by CH-CH arylation reaction for high-performance thin-film transistors

Abstract

Three homopolymers were successfully synthesized by direct CH-CH arylation polymerization of thieno[3,4-c]pyrrole-4,6-dione or pyromellitic diimide derivatives affording highly purified polymers with high molecular weights (43.0-174.7 K). Thieno[3,4-c]pyrrole-4,6-dione and pyromellitic diimide derivatives are considered as electron-withdrawing units. The synthesized homopolymers P1, P2, and P3 showed band gaps in the range of 2.13-2.08 eV, respectively. The electron mobilities of the three homopolymers have been investigated. The thin film transistor for P1 prepared by the eutectic-melt-assisted nanoimprinting method achieved an electron mobility of 2.11 × 10^-3 cm² s^-1 V^-1. Based on the obtained results, the synthesized polymers can be used as potential electron acceptors in solar cell applications.

Scheme 1. Synthesis of the polymers by CH–CH arylation polymerization.

Fig. 1. UV-vis absorption spectra of P1, P2 and P3 (a) in solution and (b) as casted film. Chloroform was used as the solvent.

Fig. 2. Cyclic voltammograms of homopolymers P1, P2, and P3 measured in a 0.1 M solution of TBAPF₆ in acetonitrile at a scan rate of 50 mV s⁻¹.

Fig. 3. X-ray diffraction (XRD) patterns of P1, P2 and P3. Films for XRD measurement were prepared by drop casting in CHCl₃ (10 mg ml⁻¹ of solvent) on the silicon substrate.

Fig. 4. SEM image of the wire patterns of P1 created by EMAN.

Fig. 5. Representative (a) transfer and (b) output curves of FET device using P1 show electron mobility of 2.11 × 10⁻³ cm² s⁻¹ V⁻¹.