Enhanced Thermoelectric Performance and Electronic Transport Properties of Ag Doped Cu2 xS0.5Se0.5

In addition to eco friendliness and low raw material cost, Cu2S0.5Se0.5 exhibits promising middle to high temperature thermoelectric performance by the virtue of the coexistence of liquid like phonon transport and electron crystal like charge transport. Toward higher thermoelectric performance, however, in depth studies of the electrical conduction mechanism are scarce. Herein, we investigate the electrical transport mechanism and improve the thermoelectric performance of Cu2S0.5Se0.5 by introducing Cu vacancies and substituting Cu with Ag. An optimized electronic quality factor in conjunction with a reduced lattice thermal conductivity leads to a state of the art figure of merit zT amp; 8764; 1.23 at 773 K and an average zT amp; 8764; 0.47 between 295 and 773 K in Ag0.02Cu1.955S0.5Se0.