Two-dimensional SnSe₂/Bi₂Se₃ vertically stacked heterostructures for enhanced photoresponse through tuning layer...

Two-dimensional (2D) materials have attracted much attention due to their unique structures and excellent optoelectronic properties. In this work, we fabricated c-axis-aligned SnSe₂/Bi₂Se₃ 2D heterostructures via a hydrothermal technique, where the epitaxial growth of Bi₂Se₃ nanoplates is achieved on SnSe₂ microplate substrates. The electronic states at the interfaces can be regulated facilely via tuning the Bi₂Se₃ nanoplate coverage. The heterostructure not only increases the wavelength range over which light is absorbed, but also promotes the separation and migration of photo-excited charge carriers. Therefore, the heterostructure-based photodetector attains a photoresponse that outperforms those devices composed of pure SnSe₂ and Bi₂Se₃ by a factor of 3.0 and 4.9, respectively. Furthermore, the optimal heterostructure generates a photocurrent of 289 μA cm^-2 under ultraviolet illumination, which surpasses those of recently reported state-of-the-art photodetectors. Accordingly, this work establishes an effective approach for developing low-cost, high-performance optoelectronic devices based on 2D chalcogenides.