Dual-functional self-powered broadband photodetector based on hybrid-dimensional Bi₂S₃ quantum dots/WO₃ nanoplates heterostructure arrays for multi-spectral imaging and encrypted optical communication

The self-powered broadband photodetector has attracted significant attention due to the ability of detecting optical signals across a wide wavelength range without extra energy. Herein, the Bi₂S₃/WO₃ nanoplates arrays (NPAs) with two-dimensional/zero-dimensional (2D/0D) heterostructure are facilely synthesized via a hydrothermal method cooperated with a room-temperature successive ionic layer adsorption and reaction approach. 2D WO₃ nanoplates with an average thickness (edge length) of approximately 50 nm (2 μm) are densely and uniformly covered by 0D Bi₂S₃ quantum dots on the surface. The Bi₂S₃/WO₃ NPAs photodetector exhibits satisfactory photoresponse from the ultraviolet (UV), visible (Vis) to infrared (IR) spectrum at zero bias, achieving the highest responsivity of 13.4 mA/W and detectivity of 4.14 × 10¹⁰ Jones. Furthermore, not only the fresh device, but also the one after even 40-day storage and 450 cycles operation still maintains robust response with minimal degradation of photocurrent. Moreover, the detection mechanism of the photodetector has been investigated in detail. Ultimately, the Bi₂S₃/WO₃ NPAs photodetector at zero bias achieves high-quality multi-spectral imaging to display distinct character of “H, I, T”. And the secure transmission of confidential information of “HITMSE” is realized based on the device by UV light communication with IR light encryption.