Systematic Investigationof Isoindigo-Based PolymericField-Effect Transistors: Design Strategy and Impact of Polymer Symmetryand Backbone Curvature.

Ten isoindigo-based polymers were synthesized, and theirphotophysicaland electrochemical properties and device performances were systematicallyinvestigated. The HOMO levels of the polymers were tuned by introducingdifferent donor units, yet all polymers exhibited p-type semiconducting properties. The hole mobilities of these polymerswith centrosymmetric donor units exceeded 0.3 cm2V–1s–1, and the maximum reached 1.06cm2V–1s–1. Becauseof their low-lying HOMO levels, these copolymers also showed goodstability upon moisture. AFM and GIXD analyses revealed that polymerswith different symmetry and backbone curvature were distinct in lamellarpacking and crystallinity. DFT calculations were employed to helpus propose the possible packing model. Based on these results, wepropose a design strategy, called “molecular docking”,to understand the interpolymer π–π stacking. Wealso found that polymer symmetry and backbone curvature affect interchain “moleculardocking” of isoindigo-based polymers in film, ultimately leadingto different device performance. Finally, our design strategy maybeapplicable to other reported systems, thus representing a new conceptto design conjugated polymers for field-effect transistors. [ABSTRACT FROM AUTHOR]