No abstract

Low‐cost, deformable visible‐near‐infrared (visible‐NIR) photodetectors can be configured into non‐planar shapes to meet emerging optical needs. However, it remains challenging to develop low‐cost flexible visible‐NIR photosensor with excellent mechanical deformability and high optical detectivity. Herein, we report a flexible visible‐NIR organic photodetector (OPD) based on a blend film of D18:BTP‐4F as the active layer on a polyethylene naphthalate substrate. Owing to the low exciton binding energy of BTP‐4F and the preferred orientation of the D18:BTP‐4F film, the as‐fabricated OPD exhibits excellent self‐powered optoelectronic performances with a high responsivity, high detectivity, and fast response time of 206 mA W−1, 6.45 × 1012 Jones (1 Jones = 1 cm Hz1/2 W−1), and 9 µs at the wavelength of 800 nm and bias voltage of 0 V, respectively. After 1000 bending/releasing cycles with an angle of 150° at a radius of curvature of 3 mm, the current‐voltage curves remain stable both measured under dark and light illumination, indicating obvious device operation robustness. The reliable linear photosensitivity of the as‐obtained OPD is demonstrated by the photoresponse under a range of different incident light intensities and its practical application for wearable health monitoring such as heart rate measurement is well demonstrated. Furthermore, a flexible visible‐NIR image sensor for imaging acquisition is shown by demonstrating 5 × 5 OPD array under 850 nm light irradiation. The collective results on blend film design, flexible device fabrication and characterization, and imager development shed light on sought‐after visible‐NIR photosensing and imaging systems.