Impact of hole-doping on the thermoelectric properties of pyrite FeS2

We present a comprehensive first-principles analysis of the thermoelectric transport properties of hole-doped pyrite FeS2 that includes electron–phonon interactions. This work was motivated by the observed variations in the magnitude of thermopower reported in previous experimental and theoretical studies of hole-doped FeS2 systems. Our calculations reveal that hole-doped FeS2 exhibits large positive room-temperature thermopower across all doping levels, with a room-temperature thermopower of 608 μV/K at a low hole-doping concentration of 10¹⁹ cm⁻³. This promising thermopower finding prompted a comprehensive investigation of other key thermoelectric parameters governing the thermoelectric figure of merit ZT. The calculated electrical conductivity is modest and remains below 105 S/m at room-temperature for all doping levels, limiting the achievable power factor. Furthermore, the thermal conductivity is found to be phonon driven, with a high room-temperature lattice thermal conductivity of 40.5 W/mK. Consequently, the calculated ZT remains below 0.1, suggesting that hole-doped FeS2 may not a viable candidate for effective thermoelectric applications despite its promising thermopower.