A Highly Light-Responsive Detachable Photosensor with Integrated Semiconductor-Electrolyte Layers for Enhanced Photoresponse

Organic electrochemical transistors (OECTs) gain significant attention due to their low-voltage operation, high transconductance, and biocompatibility. However, conventional OECTs face a fundamental challenge in photosensing applications: severely compromised photoresponse caused by light scattering at the electrolyte-semiconductor interface, where the stacked configuration gives optical losses through reflection, refraction, and scattering. Here, a highly light-responsive detachable photosensor featuring an integrated semiconductor-electrolyte layer configuration is developed. Our approach eliminates light scattering interfaces by introducing a π-ion film/mesh structure based on DPP-DTT conjugated polymer integrated with BMIM:TFSI ionic liquid, creating a seamless mixed ionic-electronic conductor that allows direct light access to photoactive materials. This architecture demonstrates dramatically superior optoelectronic performance compared to conventional DPP-DTT film OECTs. The π-ion film/mesh device achieved 2.78 times enhancement in responsivity of 3.98 × 10² A W¹⁻, 23.7 times improvement in photocurrent ratio of 9.04 × 10¹, and 1.46 times improved specific detectivity. The detachable design enables practical reusability, maintaining stable performance through approximately 100 electrical cycles and 4 mechanical detach/attach operations. The detachable π-ion film/mesh photosensor technology establishes design principles for next-generation organic optoelectronic devices, offering practical advantages for sustainable, high-performance sensor applications.