High‐Performance Self‐Filtering Organic Photodetectors with Photomultiplication Narrowing

Abstract Narrowband organic photodetectors (OPDs) conventionally necessitate high applied biases to accommodate a sufficiently thick active layer for self‐filtering functions. Herein, a concept leveraging the photomultiplication (PM) process is proposed to achieve spectral narrowing in OPDs which can operate at low external biases. This PM narrowing mechanism integrates two distinct functions through a pseudo bilayer structure comprising a photon‐filtering (PF) layer and a PM layer, respectively. The initial PF layer absorbs short‐wavelength photons and selectively permits light within a narrow bandwidth at the band edge of the PF material to enter the subsequent PM layer, thereby initiating the PM effect. The combined action of these two layers synergistically empowers the OPDs to exhibit a pronounced PM effect, resulting in a notably high external quantum efficiency of 5840% at a narrowband peak of 680 nm under a low bias of −5.0 V. Furthermore, the OPDs achieve a substantial −3 dB bandwidth of 5.2 kHz, alongside a maximum detectivity of 2.60 × 10¹³ Jones. These findings position the OPDs among the top‐performing self‐filtering narrowband detectors, particularly for those capable of functioning at low external biases.