Molecularly Tailored Elastomeric Block‐Copolymers for Intrinsically Stretchable Organic Field‐Effect Transistors

Although block‐copolymer based elastomeric materials have extensively served as the fundamental matrix in intrinsically stretchable transistors, systematic molecular engineering to maximize their intrinsic properties remains largely unexplored. Here, a molecular engineering approach for a representative block‐copolymeric elastomer is introduced, styrene‐ethylene‐butylene‐styrene (SEBS), by systematically tuning the styrene/ethylene‐butylene (S/EB) molar ratio. Precise molecular control over morphology and interfacial properties enabled the enhancement of stretchability, semiconductor nanoconfinement, metal‐elastomer intermixing, and dielectric stability. These improvements result from controlled aggregation of styrene‐derived hard blocks, creating pseudo‐crosslinking points, while the hydrogenated butadiene soft blocks provide rubber elasticity for each component consisting of the transistor. SEBS based each components of the transistor (S/EB: 18/82, 20/80, and 18/82 for electrode, dielectric and semiconductor, respectively) demonstrated superior device performance, maintaining charge mobility (>90% retention after 10,000 stretching cycles at 50% strain), electrode conductivity (>10⁴ S cm −1 under deformation), and stable dielectric properties (breakdown strength >1.5 MV cm −1 under strain). Fully stretchable active‐matrix transistor arrays and logic circuits (Inverter, NAND, and NOR) using a unified SEBS platform exhibited exceptional operational stability under 30% biaxial strain. Our molecularly tailored SEBS platform provides versatile design principles for advanced wearable healthcare sensors, electronic skins, and bio‐integrated electronic systems.