A broadband polarization-sensitive photodetector and an infrared encoder based on high crystallinity 1D Bi₂(Se,S)₃...

The realization of multifunctionality and integration in one device is of great significance for the development of current information technologies. However, it often requires the design of heterojunctions or external conditions, which leads to complex fabrication processes and increased power consumption. Besides, the study and utilization of the special negative photoconductivity (NPC) effect is still in its early stage and remains limited. One-dimensional (1D) nanowires have great potential in the optoelectronic application field due to their unique chain structure, strong anisotropy, and possible NPC characteristics. Herein, an alloying strategy was proposed to synthesize 1D Bi₂(Se,S)₃ ternary nanowires with high crystallinity and uniformity via a chemical vapor deposition method. The photodetector based on a single Bi₂(Se,S)₃ nanowire shows broadband response (405-1550 nm), high responsivity (5.31 A W^-1), excellent specific detectivity (1.87 × 10¹¹ Jones) and fast response speed (0.43/0.47 ms). Furthermore, it exhibits strong polarization sensitivity with anisotropy ratios of 2.25 (638 nm), 1.76 (980 nm) and 1.54 (1550 nm), and achieves polarization-sensitive imaging capability. Notably, an infrared encoder was simulated based on the NPC effect under a 1550 nm laser which can be modulated effectively by laser power intensity for the first time. The NPC phenomenon is due to the photogenerated carriers which are trapped by recombination centers in the deep trap energy levels (E_trap) at lower power intensity. These findings provide a promising strategy for the study of the NPC phenomenon, and the development of high-performance multifunctional photodetection and communication encryption.