Enhancing Photocurrent Efficiency in Filter‐Less NIR Organic Photodetectors Through a Photomultiplication‐Inducing Perovskite Quantum Dot Interlayer

Abstract

AbstractA unique charge‐injection‐narrowing organic photodetector (CIN OPD) is demonstrated for near‐infrared (NIR) range operation. In conventional CIN OPDs, photomultiplication (PM) is achieved within a bulk heterojunction (BHJ) active layer with a donor:acceptor ratio of 100:1. Unfortunately, this approach encounters an issue in which the narrowband detection wavelength is determined solely by an excessive donor quantity. Consequently, the conventional devices face a critical limitation in that their detection range cannot extend to longer wavelengths. However, this limitation has been overcome through a novel mechanism and have fabricated a device that responds at λ = 940 nm. When a perovskite quantum dot interlayer is inserted as the PM‐inducing layer, PM occurs outside the active layer. Therefore, the BHJ active layer is structured with a donor:acceptor ratio of 50:50, resulting in an extension of the detection wavelength to the absorption tail of the narrow‐bandgap acceptor. The device demonstrates a remarkable external quantum efficiency (EQE) of 39 000% with a narrow full‐width at half‐maximum (FWHM) of 98 nm at 60 V. It also has a high specific detectivity and a short response time. The device represents a significant advancement in filter‐free, high‐efficiency photodetectors suitable for optical sensor applications such as light detection and ranging (LiDAR).