Sensitive Filter‐Free Narrowband Infrared Photodetectors for Weak Light Detection and Ranging

Abstract Light detection and ranging (Lidar), which utilizes scattered near‐infrared (NIR) light to identify objects, has shown great potential in remote sensing, autonomous driving, robotic vision, etc. However, the intensity of the scattered NIR light is significantly reduced, placing stringent demands on the selectivity and fast response of the sensing. Even though optical filters can be used to select weak signals, the photon losses arising from additional interfaces are inevitable, thus reducing the signal‐to‐noise ratio (SNR). In this work, a series of organic narrowband photodetectors are constructed with tunable and selective responses from 700 to 950 nm with a minimum full‐width‐at‐half‐maximum (FWHM) of ≈30 nm. To enhance response sensitivity and speed, delicate and compact photodiode architecture is applied through comprehensive device engineering. As a result, the detectors possess a sensitive response to weak NIR light with a detection limit of 3 nW, and response rise time ( τ r ) and decay time ( τ d ) of ≈24 ns and ≈1.3 µs, respectively. Moreover, a proof‐of‐concept Lidar based on these organic photodetectors is demonstrated with a distance resolution of ≈10 cm, which further confirms the great potential in practical application.