Tuning thermoelectric figure of merit in Ag doped nanostructured PbSnTeSe alloy by entropy and band engineering phenomena

Abstract

Advanced thermoelectric materials with novel chemistry and structure that exhibit superior functional properties are in high demand in today's scientific scenario. Engineered configurational entropy in bulk thermoelectric materials through complex chemical disorder is an emerging and potential approach to achieve exceptional thermoelectric properties over traditional material systems. In the current study, mechanical alloying (MA) and spark plasma sintering (SPS) were used to synthesize the high-density (>96%) nanocrystalline lead tin tellurium selenium (PbSnTeSe) high entropy alloy (HEA) with varied atomic concentrations of silver (Ag) doping (0–0.9 at%). The high entropy, band engineering and nanostructuring approach synergistically show a remarkable decrease to ultralow thermal conductivity (0.814 W/mK), resulting in a substantial increase in the power factor (14.16×10−4W/mK2). Thus, an excellent figure of merit (ZT=0.891) is achieved in PbSnTeSe doped with 0.9Ag HEA at 573 K, which is estimated as a 225% increase over the pristine PbSnTeSe HEA (ZT=0.396).