Impact of Boron Nitride on the Thermoelectric Properties and Service Stability of Cu_{2- x}Se

Improving the thermoelectric performance and service stability is essential for the effective use of cuprous selenide (Cu_2-xSe). In this study, hexagonal boron nitride (h-BN) was incorporated into nano-Cu_2-xSe, with the goal of enhancing thermoelectric performance and service stability. It was found that Cu_2-xSe-0.005 wt % BN showed a higher thermoelectric figure of merit (zT) value (∼1.76 at 923 K), which was 11% greater than that of pure Cu_2-xSe, mainly due to a significant reduction in lattice thermal conductivity (k_L) to about 50% (0.13 W m^-1 K^-1). Additionally, the formation of an ion-blocking interface by hexagonal boron nitride effectively shortens the migration path of Cu⁺ ions, improving service stability while maintaining the contribution of Cu⁺ transitions to thermal conductivity. Finally, an increase in hardness of ∼11.1% was observed, reaching 0.7 GPa in Cu_2-xSe-0.02 wt % BN. This research is a feasible approach to improving the service stability of Cu_2-xSe.