Lattice thermal conductivity of silicon monolayer in biphenylene network

Recently, the two-dimensional carbon sheet in a biphenylene network has been successfully fabricated by experiment [Fan et al., Science 372, 852 (2021)], promoting the study of silicon allotropes with similar structures. In this work, we investigate the lattice thermal conductivity of a silicon monolayer in a biphenylene network through first-principles calculations. It is found that the thermal conductivity is anisotropic and much lower than that of carbon sheets with a similar structure. At 300 K, the thermal conductivity is 2.46 and 3.25 W m−1 K−1 along the two crystallography directions, respectively. The phonon group velocity, relaxation time, and the contribution of each mode to total thermal conductivity are analyzed, to understand the underlying physical mechanisms of the low thermal conductivity. Our work provides fundamental insights into thermal transport in the silicon monolayer in the biphenylene network and should stimulate further experimental exploration of these materials for possible thermoelectric and thermal management applications.