2D AgTiPS₆: a Cross‐Stacked In‐Plane Anisotropic Semiconductor for Broadband and Polarization‐Sensitive Photodetection

Abstract

Abstract2D anisotropic materials, typically consisting of 1D distorted chains arranged in parallel or anti‐parallel patterns, are gaining attention for their potential in anisotropic electronic and optoelectronic devices. 2D anisotropic materials with cross‐stacked interconnected 1D chains will show improved anisotropy and stability. Nonetheless, to date, no 2D anisotropic materials featuring cross‐stacked motifs have been experimentally realized. This work identifies AgTiPS6 atomic layers, the 2D in‐plane anisotropic material with cross‐stacked structural motifs, as an n‐type semiconductor with a 1.0 eV band gap. Significantly, the unique cross‐stacked configuration of 2D AgTiPS6 results in a significant in‐plane anisotropy, with electrical and optoelectrical anisotropies measuring 5.44 and 2.44, respectively, as well as an axially orientation selectivity. Meanwhile, a broadband response from visible (Vis, 405 nm) to middle infrared (MIR, 10.6 µm) is achieved in the AgTiPS6‐based photodetector, with the photoresponse above the bandgap attributed to photothermoelectric effect. Furthermore, 2D AgTiPS6 has demonstrated environmental stability exceeding 12 months and a laser damage threshold exceeding 10 W cm−2, attributed to its extra‐thick monolayer (1.32 nm). This work introduces a novel in‐plane anisotropic material, expanding the repertoire of 2D anisotropic materials and offering potential for the development of anisotropic electronic and optoelectronic devices.