Tuning p-type semiconduction with ultra-low thermal conductivity in nanocrystalline n-type BiSbTe_{1. 5}Se_1.5 high entropy alloy via Ag doping

The current investigation reports the tuning of p-type semiconduction in nanocrystalline BiSbTe_{1. 5}Se_1.5 high entropy alloy (HEA) by Ag doping (0.3–0.9 at%) processed through mechanical alloying (MA) and spark plasma sintering (SPS). The entropy engineering and nanostructuring phenomena synergistically lower the thermal conductivity (K) below 1 W/mk in all samples. The superior ZT value of 0.45 is achieved in p-type BiSbTe_1.5Se doped with 0.6 at% Ag doping, comparable with its n-type BiSbTe_1.5Se_1.5 possessing ZT of 0.43 at 523 K. The consistency in material chemistry and identical temperature dependence of ZT in both p-type and n-type materials of the current investigation provide promising perspectives for developing low-loss thermoelectric generators.