The impact of sintering temperature on the thermoelectric performance of Cu2Se synthesized by solid state reaction method

In this study, copper selenide (Cu2Se) compounds were synthesized using a solid-state reaction technique and post-sintering processes (573 ​K–973 ​K). The mass density of the Cu2Se compounds decreased with increasing sintering temperatures due to changes in grain morphology and an increase in the number and size of pores in the samples. The sintering temperature also affected carrier generation mechanisms, which directly impacted the electrical transport characteristics and thermal properties. The α→β phase transition at around 400 ​K was observed in all samples. The low thermal conductivity was mainly attributed to the low lattice thermal conductivity (κlattice). As the result, the sample sintered at 773 ​K showed an outstanding ZT value of 1.44 ​at 773 ​K, with a power factor of 12.1 μWm−1K−2 and the thermal conductivity of 0.65 Wm−1K−1. The sintering temperature dependence of thermal conductivity was elucidated in terms of the growth of microstructural pores.