Elementally Biocompatible Flexible Optoelectronic Platforms With Intrinsic UV Dose Integration and Transient Sensing‐Computing Capability

ABSTRACT

Excessive UV exposure is a major cause of skin damage, yet practical wearable UV monitoring systems require not only mechanical compliance but also long‐term biological and environmental compatibility. Here, we report an elementally biocompatible flexible optoelectronic transistor (EBOT) platform in which all functional components are constructed from physiologically relevant elements. Zn‐Mg‐based oxides serve as the semiconductor and dielectric layers, Mg acts the electrode, and biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P34HB) provides a flexible substrate and encapsulation layer. A low‐temperature, all‐hard‐mask fabrication strategy enables device and circuit patterning without photolithography, preserving the compatibility of the constituent materials. Post‐fabrication supercritical‐fluid treatment further optimizes the device characteristics, improving the on/off ratio, responsivity and detectivity by 48.1%, 7.5% and 16.8%, respectively. Rather than eliminating persistent photoconductivity, we harness defect‐mediated carrier trapping and relaxation as an intrinsic temporal integration mechanism, allowing a single device to simultaneously encode UV dose and exposure history without additional memory components. The EBOT platform exhibits excellent cytocompatibility and mechanical durability over 1,000 bending cycles. Furthermore, vertically integrated sensing‐computing architectures are demonstrated by stacking photodetection and logic functionalities, providing a pathway toward highly integrated transient bioelectronic systems. This work establishes an elementally compatible strategy for developing flexible and environmentally transient optoelectronic platforms.