Molecular dynamics investigation of Moiré pattern dependent thermal conductivity in hBN-phosphorene heterostructure

Black Phosphorene (BP) has surfaced as a viable material for designing devices that require thermoelectric anisotropy for applications like electronics, photonics, and optoelectronics. However, BP is chemically and environmentally unstable and requires encapsulation with a stable two-dimensional (2D) material. Hexagonal boron nitride (hBN) is commonly used for this purpose. Van der Waals (vdW) heterostructures of BP with hBN can impart distinct material properties without compromising BP's unique anisotropy. Moreover, introducing twist angle as an additional degree of freedom enables easy manipulation of properties by forming Moiré superlattices, which remains unexplored for the BP/hBN heterostructure. This study uses nonequilibrium molecular dynamics simulations (NEMD) to investigate the in-plane thermal conductivity (TC) of a 9.3 × 9.3 nm BP/hBN heterostructure as a function of hBN twist angle. Our findings show that, along both the zigzag (zz) and armchair (ac) directions, the in-plane TC varies with twist angle in a W pattern, with values repeating every 30º rotation of the Moiré pattern. For the zz direction, TC ranged from 21.81 to 26.10 W/mK, while the ac direction had 13.91–17.83 W/mK. The TC increased by 3.92 and 7.47 times that of monolayer BP on average along zz and ac directions. There was an average drop in anisotropy to 1.57. It is evident from PDOS analysis that the anisotropy of BP/hBN is independent of twist angles, while the thermal conductivity depends on PDOS overlap. These findings show the potential of twist engineering as an effective strategy to modulate the TC of BP/hBN heterostructures.