PdSe₂/MoSe₂ vertical heterojunction for self-powered photodetector with high performance

Van der Waals’ two-dimensional (2D) material heterostructure engineering offers an effective strategy for the design of multifunctional and high-performance optoelectronic devices. However, 2D heterostructure photodetectors with a photoconductive effect tend to suffer from high driving source-drain voltages and significant dark noise currents. Herein, a self-powered photodetector with high performance was fabricated based on vertically stacked graphene/MoSe₂/PdSe₂/graphene heterojunctions through a dry transfer method. The fabricated device displays current rectification characteristics in darkness (on/off ratio > 10 ³) and superior photovoltaic behaviors under illumination. In addition, benefitting from the strong built-in field, the Gr/PdSe₂/MoSe₂/Gr heterojunction photodetector is able to respond to a broad spectrum from visible to near-infrared (NIR) with a remarkable responsivity of 651 mA·W⁻¹, a high specific detectivity of 5.29 × 10¹¹ Jones and a fast response speed of 41.7/62.5 μs. Moreover, an enhanced responsivity of 1.16 A·W⁻¹ has been obtained by a reverse voltage (−1 V) and further evaluation on image recognition has also demonstrated the great application potential of the Gr/MoSe₂/PdSe₂/Gr heterojunction photodetector. The findings are expected to bring new opportunities for the development of highly sensitive, high-speed and energy-efficient photodetectors for comprehensive applications.