Ultrahigh-sensitivity organic photodetectors processed with a non-halogenated solvent for a self-powered mechano-optoelectronic coupled sensing system

The development of high-performance organic photodetectors (OPDs) currently depends on highly toxic halogenated solvents for processing and on an external power source to drive illumination. Here, we report high-sensitivity rigid and flexible self-powered OPDs processed with the environmentally friendly solvent <i>o</i>-xylene. Especially, the flexible OPD achieves a record responsivity of 0.55 A W^-1, along with an ultralow dark current of 0.44 nA cm^-2 and excellent bending stability. By further integrating a mechanoluminescent (ML) unit as a self-powered light source, we demonstrate a ML-OPD sensing system that operates without external power and illumination. Notably, the visible-near infrared broad spectral response of the OPD exhibits a high degree of overlap with ZnS:Cu and other multicolor ML units, ensuring efficient inter-unit optoelectronic energy transform. The ML-OPD system demonstrates dual functionality for real-time motion sensing and gesture recognition by converting mechanical finger flexion/extension (0°-45°) into quantifiable current signals to track continuous motions, while utilizing distinct combinatorial current signatures from multi-finger pattern actuation to execute gesture recognition feedback without visual assistance. This integration of self-powered mechano-optoelectronic transduction establishes a new paradigm for distributed optoelectronic sensing, with future scalability toward multimodal human-machine interaction (HMI) systems requiring ultralow-power operation and spatial adaptability.