Ultra-high carrier mobility and ultra-low lattice thermal conductivity in PdSSe monolayers with fully Stone–Wales defects.

This article focuses on the engineering and characterization of Stone–Wales (SW) defects in two-dimensional (2D) pentagonal PdSSe monolayers, resulting in four novel defect structures labeled SW1–SW4. Using first-principles calculations, these SW defect structures are shown to maintain square-planar coordination and exhibit excellent dynamical, mechanical, and thermal stability, with SW1 and SW2 possessing direct bandgaps favorable for electronic transitions and photocatalytic water splitting. The defected PdSSe monolayers demonstrate ultra-high carrier mobilities (~10³ cm²V⁻¹s⁻¹), strong visible-light absorption (~10⁵ cm⁻¹), and ultra-low anisotropic lattice thermal conductivities (<2 Wm⁻¹K⁻¹ at room temperature), suggesting their potential for applications in nanoelectronics, optoelectronics, solar energy conversion, photocatalysis, and thermoelectric devices. The study highlights the impact of SW defect engineering on tuning electronic, optical, and thermal transport properties in pentagonal 2D materials.