Thermoelectric properties of S-doped Cu2Se materials synthesized by high-pressure and high-temperature method

摘要

High-pressure technique is an effective route to synthesize thermoelectric materials and tune transport properties simultaneously. In this work, S-doped copper-selenium compounds (Cu2Se1-xSx, 0 <= x <= 0.05) were successfully synthesized by high-pressure and high-temperature (HPHT) technology in just 30 min. Cu2Se1-xSx samples show layered morphology composed of abundant pores and lattice defects. The appropriate S introduction (x = 0.01 and 0.03) can effectively enhance Seebeck coefficient and reduce the thermal conductivity of Cu2Se. Compared with the pure Cu2Se sample, Cu2Se0.97S0.03 exhibits a 30% lower thermal conductivity, but the decline of power factor by the distinctly increased electrical resistivity at high temperature results in a smaller zT at temperature >650 K. The variations of thermoelectric properties are resulted from the competitive effects between S-doping and actual composition change (Cu:S). It indicates that S-doping is not so effective in improving the zT value of Cu2Se materials by high-pressure synthesis.