Boosting thermoelectric performance of ferroelectric monolayer α-In2Se3 via strongly enhanced phonon scattering induced by site-specific Te doping

The thermoelectric properties of ferroelectric monolayer α-In2Se3 with site-specific Te doping are systematically investigated using first-principles calculations and on-the-fly machine-learning-assisted phonon transport simulations. Te substitution at different atomic layers leads to a substantial reduction in lattice thermal conductivity, primarily due to enhanced phonon scattering induced by mass contrast and local structural asymmetry. The electronic transport characteristics, including band dispersion, carrier effective mass, and Seebeck coefficient, remain largely unaffected, ensuring preserved power factor. As a combined result, the thermoelectric figure of merit (zT) increases from approximately 0.4 in the pristine structure to nearly 2.5 at 600 K in the optimally doped configuration. These findings demonstrate the impact of doping-site selectivity and data-driven anharmonic modeling on the thermoelectric performance of two-dimensional ferroelectric materials. Moreover, the top and bottom doping configurations are related by ferroelectric switching, enabling potential modulation of thermal transport and thermoelectric properties via polarization reversal.