Impact of Boron Nitride on the Thermoelectric Properties and Service Stability of Cu2–xSe

Improving the thermoelectric performance and service stability is essential for the effective use of cuprous selenide (Cu2–xSe). In this study, hexagonal boron nitride (h-BN) was incorporated into nano-Cu2–xSe, with the goal of enhancing thermoelectric performance and service stability. It was found that Cu2–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 Cu2–xSe, mainly due to a significant reduction in lattice thermal conductivity (kL) 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 Cu2–xSe-0.02 wt % BN. This research is a feasible approach to improving the service stability of Cu2–xSe.