Strong Anisotropy and Giant Photothermoelectricity of 1D Alloy Nb₃Se₁₂I‐Based Photodetector for Ultrabroadband Light‐Detection and Encryption Imaging Application

Abstract Securing high‐capacity and safe communication holds great potential for ushering in the new era of digital society. In this study, a wide‐band photodetector based on the quasi‐1D niobium selenide compounds (Nb₃Se₁₂I), showing up photothermoelectric (PTE) dominated multiple synergistic effects with high responsivity across a wide wavelength range from deep‐ultraviolet (254 nm) to terahertz (0.30 THz), providing an efficient strategy for high‐capacity optical processing is introduced. Combined with the polarized‐sensitive property of the Nb₃Se₁₂I photodetector, an encrypted imaging technology using polarization‐resolved PTE current is developed. This technology is capable of transforming encrypted messages into polarization states, which can be restored through a specially designed decryption algorithm, greatly enhancing the concealment and security of the information transmission process. Overall, the Nb₃Se₁₂I‐based detector manifests in terms of high responsivity (283.2 A W⁻¹ to 520 nm, 1632.4 A W⁻¹ to 980 nm, and 1868.1 A W⁻¹ for short‐wave infrared light of 2200 nm), suitable response speed of 43 µs for 0.30 THz wave and polarization anisotropy ratio of 1.83. The versatile abilities of photodetector in the realm of ultrabroadband polarized detection and encryption imaging may advance the use of anisotropic thermoelectric materials in high‐capacity and secure information communication applications.