Narrowband Near‐Infrared Photodetector Enabled by Dual Functional Internal‐Filter‐Induced Selective Charge Collection

Abstract The spectral selective detection of the near‐infrared (NIR) signals is important for biological sensing, healthy monitoring, and intelligent communication. Herein, a new method to fabricate a visible‐blind NIR‐sensitive narrowband photodetector (NPD) with excellent comprehensive performances is reported. The organic bulk heterojunction (OBHJ) thin film, based on an NIR‐sensitive organic acceptor, is employed to provide fast photoresponse, with adjustable cutoff edge. The key strategy of introducing a solution‐processable optical/electric bifunctional internal filter (CH₃NH₃PbI₃ (MAPbI₃)/CuSCN) realizes the selective collection of the NIR‐induced charge carriers. Further combined with the suitable energy level and high mobility of the MAPbI₃/CuSCN layer, the extraction of NIR‐light‐induced charges from OBHJ is promoted efficiently. The NPD with optimized structure exhibits narrowband NIR response (full width at half maximum (FWHM) < 100 nm) with maximum external quantum efficiency value up to 74.26% and detection limit down to 3.6 pW cm⁻², both of which are the best values among the ever reported NIR NPDs. The highest responsivity reaches 0.485 A W⁻¹ in the NIR region, with a large linear dynamic range of 162 dB. The specific detectivity is close to 10¹³ Jones, enabling the device to detect weak NIR signals.