High-performance multifunctional La₂X₃Sb₈ (X = Mn, Fe) skutterudites for energy harvesting and optoelectronic applications

The multifunctional La₂X₃Sb₈ (X = Mn, Fe) skutterudites can be significantly enhanced strategic compositional tuning. We employ density functional theory (DFT) with Coulomb correction to investigate the structural, electronic, optical, thermoelectric, and magnetic properties of doped systems. Our calculations reveal transition metals introduce localized d-states near the Fermi level ranging from 1.1 to 1.8 eV and increase in the density of states. These electronic modifications result in electrical conductivity and strong phonon scattering to thermoelectric figure of merit (ZT ≈ 0.9 at 700 K) for Fe-doped compositions. The dielectric function exhibits a redshifted into broadening the optical absorption enhanced photovoltaic and optoelectronic applications. The piezoelectric also demonstrates a notable 20 % increase in the e₃₃ coefficient due to lattice distortion and symmetry breaking at the Mn/Fe confirms strong hybridization between transition metal d orbitals, enhanced charge transport and optical activity. These synergistic improvements in electronic, vibrational, and electromechanical properties La₂X₃Sb₈ for integrated thermoelectric energy harvesting, infrared photodetection, and spintronic applications. Our findings highlight doping in skutterudites enable multifunctional performance across energy conversion, sensing, technologies.