Strengthened inter‐chain π–π contacts in amorphous diketopyrrolopyrrole polymers for robust flexible organic thin‐film transistors

Abstract Flexible organic thin‐film transistors (OTFTs) based on multi‐vinylene‐linked diketopyrrolopyrrole (DPP) polymers were developed to address the trade‐off between mechanical flexibility and charge transport. Three polymers incorporating thiophene, dithiophene, and terthiophene donor motifs (PDPPVT, PDPPVDT, and PDPPVTT) were synthesized via a halogen‐free Knoevenagel condensation. Despite their predominantly amorphous film morphologies induced by vinylene isomerization, grazing‐incidence wide‐angle X‐ray scattering analyses revealed strengthened inter‐chain π–π stacking with increasing donor ring size. Correspondingly, top‐gate/bottom‐contact (TGBC) OTFTs fabricated from these polymers exhibited progressively enhanced hole mobilities, reaching 1.203 cm 2 V −1 s −1 for PDPPVTT, surpassing the benchmark of amorphous silicon. The devices also demonstrated excellent mechanical reliability, retaining over 94% of their initial mobility under bending radii down to 2.5 mm and preserving approximately 90% of performance after 1000 bending cycles. These findings establish vinylene isomerization as an effective strategy for enhancing mechanical flexibility, while donor expansion provides a complementary route to high mobility. Collectively, this work offers a structural design framework for multi‐vinylene‐linked conjugated polymers, underscoring their strong potential for next‐generation flexible electronic applications.