Partially Degradable N-Type Conjugated Random Copolymers for Intrinsically Stretchable Organic Field-Effect Transistors

Abstract

In this study, a series of conjugated homopolymers (P1 and P5) and random copolymers (P2–P4) by copolymerizing naphthalene diimide (NDI) as the acceptor with varying ratios of two donor units, thiophene-imine-thiophene (TIT) and thiophene-vinylene-thiophene (TVT) is developed. The inclusion of TIT imparted degradability to the random copolymers under acidic conditions, offering a sustainable solution for electronic waste management. Structural analysis revealed that TIT favored edge-on molecular orientation, while TVT promoted face-on and end-to-end orientations. The synergistic combination of TIT and TVT in copolymerization resulted in balanced structural and functional properties with partial degradability conferred using the TIT units. The random copolymer P3, with an optimal equimolar TIT/TVT ratio, demonstrates superior electrical and mechanical performance. P3 exhibits an initial charge mobility of 0.10 cm² V⁻¹ s⁻¹ and maintained mobility of 0.0017 cm² V⁻¹ s⁻¹ under 20% strain, significantly outperforming P1 in mobility at almost strain levels. P3 also achieved a mobility retention of 31.3% under 20% strain, compared to 12.2% for P5. This study demonstrates that the copolymerization of TIT and TVT enables the fine-tuning of solid-state packing modes and molecular orientations, thereby improving both the stretchability and environmental sustainability of the materials.