Synergistic-engineered van der Waals photodiodes with high efficiency

Abstract

Van der Waals (vdW) heterostructures based on two-dimensional transition-metal dichalcogenides have provided unprecedented opportunities for photovoltaic detectors owing to their strong light-matter interaction and ultrafast interfacial charge transfer. Despite continued advancement, insufficient control of photocarrier behaviors still limits the external quantum efficiency (EQE) and operation speed of such detectors. Here, we propose a synergistic strategy of contact-configuration design and thickness-modulation to construct high-performance vdW photodiodes based on the typical type II heterostructure (MoS2/WSe2). Through integrating three contact architectures into one device to exclude other factors, we solid the superiority of designed 1L-MoS2/WSe2/graphene heterostructures incorporating efficient photocarrier collection and gate modulation. Together with leveraging the layer-number-dependent properties of WSe2, we observe the critical thickness of WSe2 (11 layers) for the highest EQE, which verifies the thickness-dependent competition between photocarrier generation, dissociation, and collection. Finally, we demonstrate the synergistic-engineered vdW heterostructure can trigger record-high EQE (61%) and manifest ultrafast photoresponse (4.1 μs) at the atomically thin limit (8 nm). The proposed strategy enables architecture-design and thickness-engineering to unlock the potential to realize high-performance optoelectronic devices.