2D AuPS: Revealing Giant In-Plane Anisotropy Driven by Mixed-Coordination via Stereoscopic Distortion

The growing demand for high-performance optoelectronic devices has spotlighted the scarcity of two-dimensional (2D) materials with robust in-plane anisotropy and stability, as traditional materials with one-dimensional (1D) distorted chains in parallel or antiparallel arrangements often fall short in these aspects. This work reports 2D AuPS, a semiconductor with an orthorhombic <i>Pbca</i> structure, featuring a four-layer stacked architecture and a mixed-coordination network integrating Au³⁺ square planar coordination with P^1-/S^2- trigonal noncoplanar coordination. This design induces stereoscopic distortion, creating a nonuniform electronic density gradient that enhances in-plane anisotropy. 2D AuPS leverages its indirect bandgap to facilitate efficient charge carrier separation, with its puckered structure imparting strong in-plane anisotropy in optical, electronic, and optoelectronic properties, demonstrating anisotropic ratios of 5, 12, and 16 for absorptive dichroism, conductivity, and photocurrent, respectively. The AuPS-based photodetector exhibits high performance underpinned by its ambient stability, positioning it as a candidate material for polarization-sensitive nanoelectronic and optoelectronic applications.