Two-Dimensional Graphdiyne-Black Phosphorus van der Waals Heterostructure: A Versatile Platform for Broadband Photodetection from UV to IR

Abstract

To enhance the energy harvesting capabilities of optoelectronic devices, it is necessary to achieve both broadband and targeted photodetection with improved sensitivity. To address the limitations of photodetection, the combination of small band gap semiconductors with large band gap 2D semiconductors has been found to offer additional benefits. Specifically, two-dimensional (2D) van der Waals heterostructures with customized band alignment have gained significant attention due to their potential advantages. The relation between the built-in field and optoelectrical properties of such heterostructures is not fully understood. Here, a highly sensitive air-protected phototransistor device based on van der Waals heterojunction between few-layer black phosphorus (BP) and few-layer graphdiyne (GDY) has been proposed. Black phosphorus (BP), with its small and direct tunable band gap, complements the spectral range between graphene and TMDCs and offers extraordinary electrical and mechanical properties. The optoelectrical properties and photodetection mechanism have been investigated under UV to IR wavelengths along with the computational methods. The BP/GDY FET photodetector presents ambipolar behavior with mobilities in the order of 1656.3 and 804.271 cm²/(V·s), for electron and hole, respectively, and current on/off ratios larger than 1.19 × 10⁴. Besides, the device demonstrates the high and gate-controlled photoresponsivity of R = 1267.43 and 3041.82 A W^–1 across a range of wavelengths (λ in the range of 395–940 nm) in UV and near-infrared regions, respectively. Furthermore, the BP/GDY phototransistor device shows a time response of 19 ms (rise) and 6 ms (fall). This study highlights a significant improvement in the photovoltaic properties within the ultraviolet and infrared spectra and a high energy conversion efficiency for heterojunctions based on few-layer 2D materials. This groundbreaking design has a significant potential to revolutionize the field of optoelectronics by enabling the creation of exceptional infrared photodetectors with outstanding performance.