Bisazathienoisoindigo-Based Conjugated Polymers: Synthesis, Characterization, and the Influence of Inner Bridging Units on the Quinoidal Character and Charge Transport Property

Abstract

Herein, we report three novel electron-withdrawing bisazathienoisoindigos M1, M2, and M3, in which the inner bridging units are a single bond, ethenylene, and (E)-1,2di(thiophen-2-yl)ethene (DTE), respectively. Copolymerization of the bisazathienoisoindigos with DTE afforded three conjugated polymers P1−P3. Theoretical and experimental investigations suggested that the quinoidal character of these polymers decreases from P1/P2 to P3, indicative of decreasing intramolecular charge transport. However, the P3-based transistors exhibited the best charge transport characteristics with a maximum hole mobility (μ h,max ) of 4.59 cm 2 V −1 s −1 , which is about 6 and 19 times the μ h,max of P1 and P2, respectively. Thin film microstructural characterizations revealed that P3 has more ordered lamellar and tighter π−π stacking in the solid state than those of the other two polymers, thus leading to enhanced intermolecular charge transport. This study supplies a useful approach for modulating the quinoidal properties of conjugated polymers and experimentally proves that intermolecular charge transport can dominate carrier transport of polymer semiconductors.

Quinone-Enriched Polymer with a Large π-Conjugated Structure for High-Energy Supercapacitors: Synthesis and Electrochemical Assessment

“…PDAQ/rGO-0.3 exhibits remarkable capacity retention and excellent cycle durability, which can be ascribed to the following factors: (1) With the complete π-conjugated system of PDAQ, the molecular skeleton remains stable when the functional group undergoes a redox reaction, and the structure will not be damaged, which theoretically achieves the corresponding long cycle life . (2) A large π-conjugated system for facilitating easier charge transfer during electrochemical processes and conductive substrates provides a certain catalytic effect on PDAQ, allowing for a fast faradaic reaction. , (3) The robust π–π interactions between PDAQ and rGO enable PDAQ to be well-anchored to rGO, effectively avoiding the self-discharge caused by the active species falling off and shuttling between the positive and negative electrodes. , (4) The coiled nanosheet-based 3D network structure speeds up ion transport and adequately exposes the active CO group to enhance the effective utilization of the redox active site and ensure ion accessibility. − …”

“…Through the design and synthesis of polymers containing abundant quinone and highly conjugated structures, it is possible to achieve a reversible change of redox functional groups without damaging the molecular framework. , This enables the continuous and reversible cycle of multi-electron faradaic reactions. For instance, Wei et al created and produced three electron-withdrawing bisazathienoisoindigos, named M1–M3 . Quinoidal structures can increase the flatness of the backbone and promote the spread of π electrons, which, in turn, enhances the movement of charges inside the molecule .…”

“…For instance, Wei et al created and produced three electron-withdrawing bisazathienoisoindigos, named M1–M3 . Quinoidal structures can increase the flatness of the backbone and promote the spread of π electrons, which, in turn, enhances the movement of charges inside the molecule . He et al attained a notable increase in capacitance by incorporating a redox-active organic polymer onto the surfaces of carbon fibers.…”