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

A 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 lambda = 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). A charge-injection-narrowing organic photodetector operating at near infrared range is demonstrated. This extension of the detection wavelength is achieved through a strategy of separating the charge-collection-narrowing and photomultiplication layers, resulting in an EQE of 39 000% at lambda = 940 nm. In addition, the operation mechanism of the device is analyzed and discussed through optical simulations. image