Light‐Mediated Photomultiplication via Cascade Energy Transfer in Organic Photodiode

Abstract Photomultiplication organic photodetectors (PM‐OPDs) demonstrate exceptional sensitivity in low‐light environments, making them valuable for imaging, environmental monitoring, and wearable health sensors. However, traditional PM‐OPDs require significantly high operational voltages, which lead to elevated dark current and degraded sensitivity and noise performance. To address these limitations, a novel light‐mediated PM‐OPD is introduced that enhances signal gain through a cycle of light emission and reabsorption within the photoactive layers. This design integrates emission and absorption layers, achieving an external quantum efficiency exceeding 200% while maintaining a low dark current (≈10 −9 A cm −2 ) and high specific detectivity over 5.0 × 10 13 Jones. By reabsorbing internally generated light to drive photomultiplication, the device enables efficient amplification without noise penalties. It achieves a 29.5 dB gain in photoplethysmography signal detection at 10 lux and demonstrates scalability for cost‐effective production using thermal evaporation, making it a promising solution for low‐power, high‐sensitivity wearable sensors.