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

TL;DR

This study uses first-principles calculations to analyze hole-doped FeS₂'s thermoelectric properties, revealing high thermopower but limited overall efficiency due to modest electrical conductivity and high thermal conductivity.

Contribution

It provides a detailed first-principles analysis of thermoelectric properties of hole-doped FeS₂, including electron-phonon interactions, highlighting its limitations for thermoelectric applications.

Findings

High room-temperature thermopower of 608 μV/K at low doping

Electrical conductivity remains below 10^5 S/m at room temperature

Room-temperature lattice thermal conductivity is 40.5 W/mK

Abstract

We present a comprehensive first-principles analysis of the thermoelectric transport properties of hole-doped pyrite FeS$_2$ 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 FeS$_2$ systems. Our calculations reveal that hole-doped FeS$_2$ exhibits large positive room-temperature thermopower across all doping levels, with a room-temperature thermopower of 608 $\mu$V/K at a low hole-doping concentration of 10$^{19}$ 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 10$^5$ 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 FeS$_2$ may not a viable candidate for effective thermoelectric applications despite its promising thermopower.