Advancing Intrinsically Stretchable Organic Photodetectors With a Thermoplastic Polyester Elastomer

ABSTRACT Organic photodetectors (OPDs) possess lightweight and mechanical flexibility, making them ideal for skin‐conformal wearable health monitoring devices. However, achieving simultaneously high stretchability and optoelectronic performance remains a critical challenge. Here, we report an elastomer‐semiconductor blend strategy with promising applicability across multiple representative donor‐acceptor systems, introducing a low‐cost commercial thermoplastic polyester elastomer (TPEE) into the high‐performance blend system to achieve remarkable stretchability and mechanical stability while maintaining high optoelectronic performance. The TPEE forms a continuous, ductile network at 50% content without significantly compromising the morphology or charge transport of the conjugated molecules. The resulting blend film achieves a fracture strain of 224% while retaining competitive optoelectronic performance with responsivity ( R max ) of 0.295 A W −1 and specific detectivity ( D noise * ) > 9 × 10 11 Jones. The stretchable devices retain excellent performance under 100% strain or after 1000 stretching cycles at 50% strain ( R max > 0.2 A W −1 , D noise * > 3 × 10 11 Jones). As proof of concept, we demonstrate their reliable operation in wearable near‐infrared oximeters, delivering accurate heart rate and blood oxygen readings even under strain and prolonged air exposure. This work highlights the potential of commercial elastomers in advancing high‐performance, intrinsically stretchable optoelectronic systems for practical health monitoring applications.