Resonance states and hyperconvergence induced by tungsten doping in SnTe: Multiband transport leading to a propitious thermoelectric material

•First report of hyperconvergence in conduction bands by substitutional doping of W in SnTe.•Tungsten doping in SnTe leads to introduction of resonance levels.•W doping results in increase in the band gap and valence band convergence.•Multiple electronic valley generation by W doping in SnTe leads to enhanced thermoelectric performance.•A maximum ZT of ~1.61 at 800 K is predicted by First principles calculations. Introduction of hyperconvergence in conduction bands along with increase in the band gap, valence band convergence, introduction of resonance levels and multiple electronic valley generation by tungsten doping in SnTe leads to enhanced thermoelectric performance. [Display omitted] Discovery of dopants which can engineer the electronic structure of the thermoelectric materials beneficially to improve the figure of merit has been receiving a lot of attention. In this work, we study one such unique dopant, tungsten in SnTe by implementing first principles density functional theory approach. We predict that tungsten is a n-type resonant dopant which not only increases the band gap but causes convergence of valence sub-bands leading to increased Seebeck co-efficient due to increase in the effective mass and decrease in the bipolar conduction. We show for the first time, the introduction of hyperconvergence in the conduction sub-bands, a feature which was observed only in valence bands of SnTe and GeTe. In addition to the above features, it also introduces multiple electronic valleys near the Fermi level excluding the use of a co-dopant to exploit the benefits of the electronic structure engineering. A maximum ZT of ~1.61 theoretically achieved by tuning the chemical potential at 800 K makes this material worth being explored experimentally.