Impact of Boron Nitride on the Thermoelectric Properties and Service Stability of Cu_2–xSe

Improving the thermoelectric performance and service stability is essential for the effective use of cuprous selenide (Cu 2– x Se). In this study, hexagonal boron nitride (h-BN) was incorporated into nano-Cu 2– x Se, with the goal of enhancing thermoelectric performance and service stability. It was found that Cu 2– x Se-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– x Se, 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– x Se-0.02 wt % BN. This research is a feasible approach to improving the service stability of Cu 2– x Se.