Metallic Fabry‐Pérot Cavity‐Enhanced "Pseudo‐Charge Transfer" Absorption for Efficient Narrowband Short‐Wave Infrared Photodetection

Abstract

Abstract Narrowband short‐wave infrared (SWIR) organic photodetectors, combining wavelength‐specific detection with the inherent advantages of organic semiconductors, are important candidates for many applications like medical diagnostics, industrial sorting, and environmental monitoring. However, previously reported spectral‐narrowing strategies often compromise device performance through structural complexity and intrinsic limitations of charge‐transfer (CT) absorption, even when coupled with strong cavity device architectures. To address this, a pseudo‐charge‐transfer state is engineered by doping an ultra‐narrow bandgap third component, simultaneously optimizing electrode processing to minimize parasitic absorption and interface energetic barriers. This co‐design approach yields spectrally selective photodetectors with an EQE exceeding 40% at zero‐bias at 1020 nm, a FWHM of < 60 nm, a detectivity > 3 × 1013 Jones, and an over 140dB dynamic range, while maintaining flexibility. PET‐based devices show <5% performance degradation after 3000 bending cycles. This work establishes a general design paradigm for organic narrowband photodetectors that combines laboratory‐scale performance with practical manufacturability for wearable and large‐area SWIR applications.