PdSe₂ (Palladium Diselenide)

A layered van der Waals noble-metal dichalcogenide with a puckered pentagonal (orthorhombic) structure, space group Pbca. Unlike the hexagonal TMDs, it exhibits strong in-plane anisotropy and a widely tunable, layer-dependent bandgap (from ~0 in the bulk to ~1.3 eV in the monolayer), along with high, air-stable carrier mobility. These properties make PdSe₂ an attractive candidate for anisotropic optoelectronics, high-performance field-effect transistors, and infrared photodetectors.