Vinyl flanked amorphous conjugated polymer by Knoevenagel condensation of diketopyrrolopyrrole and indacenodithiophene for flexible transistor

Conjugated polymers exhibit exceptional adaptability in flexible thin-film transistors, owing to their inherent flexibility and high charge mobility. Nonetheless, achieving conjugated polymers that demonstrate both high mobility and stability under mechanical stress, such as bending or stretching, remains a significant challenge. In this study, we synthesized an ethylene-bridged conjugated polymer, PDPPVIDT, derived from methyl-side diketopyrrolopyrrole (DPP) and indacenodithiophene (IDT) aldehydes, using an environmentally friendly Knoevenagel condensation reaction under mild conditions, resulting in a moderate yield with promising scalability. Conventional characterization techniques revealed enhanced backbone planarity with stable π-π stacking, while thin films of PDPPVIDT displayed a near-amorphous nature due to the conformational isomerism of the ethylene bond. This structure enables simultaneous charge transport and flexibility. Consequently, flexible organic thin-film transistor (OTFT) devices based on PDPPVIDT demonstrated excellent hole mobility (μ_h) reaching up to 1.70 cm² V⁻¹ s⁻¹, along with high mechanical bending resilience. This work underscores the potential of vinyl-bridged donor-acceptor conjugated polymers, highlighting the industrial adaptability of their production process and offering new insights for the design and synthesis of future flexible electronic materials.