Doping and Anisotropy–Dependent Electronic Transport in Chalcogenide Perovskite CaZrSe₃ for High Thermoelectric Efficiency

The potential of an environmentally friendly and emerging chalcogenide perovskite CaZrSe₃ for thermoelectric applications is examined. The orthorhombic phase of CaZrSe₃ has an optimum band gap (1.35–1.40 eV) for single-junction photovoltaic applications. The predictions reveal that CaZrSe₃ possesses an absorption coefficient of ≈4 × 10⁵ cm⁻¹ at photon energies of 2.5 eV with an early onset of optical absorption (≈0.2 eV) well below the optimum band gap. Seebeck coefficient, S, is inversely proportional to the carrier mobility as the calculated average effective mass for electrons is higher than for holes; p-type doping enhances the electrical conductivity, σ. The electronic thermal conductivity κ_e remains low at all temperatures. The upper limit of the thermoelectric figure of merit (ZT_e) attains ≈1.0 when doped at specific chemical potentials, while a high Seebeck coefficient contributes to the ZT_e = 1.95 at 50 K for p-type doping with 10¹⁸ cm⁻³ carrier concentration, demonstrating high thermoelectric efficiency.