Enhanced in-plane thermoelectric properties achieved through the vertical van der Waals stacking of black phosphorus and Ti2C
Yaohong Zhou, Haidong Wang
Abstract
Vertical van der Waals heterostructures (vdWHs) exhibit considerable freedom in integrating two-dimensional layered materials for achieving excellent performance. In this study, we construct a double-layer Ti 2 C/BP vdWH by stacking pristine monolayer black phosphorus (BP) and Ti 2 C vertically. The in-plane thermoelectric properties of BP, Ti 2 C and Ti 2 C/BP vdWHs at different temperatures are investigated using density functional theory combined with the non-equilibrium Green's function method. Results showed that the thermoelectric figure of merit (ZT) of Ti 2 C/BP vdWHs at room temperature (300 K) was approximately 10 3 and 10 4 times that of Ti 2 C and BP, respectively. Because of the mutual compensation of the electronic energy bands and interfacial phonon scattering, Ti 2 C/BP vdWHs have higher electron conductance and lower phonon conductance than both BP and Ti 2 C, which significantly enhances the ZT value of these structures. More importantly, the prominent thermoelectric properties of Ti 2 C/BP vdWHs maintain greater stability as the temperature rises (300–900 K), which leads to a high thermoelectric power factor and ZT value without relying on high temperatures. These results provide a new idea for designing two-dimensional functionalised nanoscale devices with excellent thermoelectric performance.