Silk Fibroin Ionotronics for High-Performance Wearable Perovskite LEDs

Hydrogels emerge as promising biointerfacing materials owing to their tunable mechanical properties and diverse biochemical functions. However, their application in electronics has been limited by the unsatisfactory conducting properties of hydrogels, typically functioning as insulators. Here, we transform the originally nonconductive silk fibroin into conductive silk fibroin ionotronics by incorporating lithium ionic salts, while maintaining high transparency, flexibility, and biocompatibility. The conductivity of the silk fibroin ionotronics was further improved to >12.4 S cm^-1 by forming a hybrid interface with PEDOT:PSS. This hybrid ionic interface was then utilized for charge injection in high-performance perovskite LEDs, achieving a brightness of 9,724 cd m^-2 and a current efficiency of 19.6 cd A^-1. Leveraging its mechanical flexibility and optoelectronic properties, a bioelectronic device for photoplethysmography (PPG) signal acquisition was demonstrated, offering an approach for intelligent human-machine interaction and advancing smart display applications in wearable systems.