Beam-Shaped Femtosecond Laser Writing of Hierarchical Pores and Textures in SbTe for Decoupling Thermal and Electrical Transport

Thermoelectric materials, which enable the direct conversion of heat into electricity, hold significant promise for clean energy utilization and waste heat recovery, yet their efficiency has historically been limited by the intrinsic coupling of thermal and electrical transport. Layered compounds such as SbTe exhibit excellent electrical conductivity but are constrained by relatively high lattice thermal conductivity, thereby impeding further improvement of the thermoelectric figure of merit (ZT). To overcome this limitation, the present study introduces femtosecond laser beam shaping as a strategy to engineer hierarchical porous structures and oriented textures in SbTe, with the objective of achieving differential modulation of phonon and electron transport. The results demonstrated that, at laser power densities of 2.54.0 J/cm, nanoscale pores (50200 nm) and microscale textures (25 m) were generated, reducing thermal conductivity from 1.42 W/(mK) to 0.68 W/(mK) (a 52% reduction) while simultaneously enhancing electrical conductivity and the Seebeck coefficient. These combined effects yielded a remarkable increase in ZT from 0.18 to 0.42, representing a 133% improvement, with a maximum value observed near 450 K. Collectively, these findings demonstrate that femtosecond laser beam shaping effectively decouples thermal and electrical transport while preserving crystal integrity, thereby establishing a promising pathway for the design of high-performance thermoelectric materials and offering important insights into the integration of multiscale processing with computational methodologies for advanced energy device optimization.