Enhancing Stretchability and Function in OFETs: A Molecular Design Paradigm via Side-Chain Engineering.

The evolution of flexible and stretchable electronics demands organic field-effect transistors (OFETs) that harmonize high electrical performance with robust mechanical compliance. While material innovation and structural designs have advanced stretchability, a fundamental trade-off often persists between charge transport and elastic deformation. Side-chain engineering emerges as a precise molecular design strategy to transcend this compromise. By decorating conjugated polymer backbones with tailored functional groups, it is possible to intrinsically engineer intermolecular interactions, packing morphology, and energy dissipation mechanisms, thereby synergistically enhancing conductivity, stretchability, and even introducing other functions like self-healing. This review systematically examines this paradigm from a functional-group-centric perspective. We first categorize and elucidate the mechanisms of key side-chain groups-alkyl, hybrid, oligoether, fluoroalkyl, composite, and special functional groups-in regulating the mechanical-electronic property nexus. Subsequently, we critically analyze the application of these engineered materials in advanced functional devices, including skin-conformal sensors, stretchable displays and photodetectors, and neuromorphic computing circuits. Finally, we provide forward-looking perspectives on the challenges and opportunities in designing next-generation side-chains for multifunctional, reliable, and commercially viable stretchable electronics.