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.