Tuning Thermal Conductivity and Electron-Phonon Interactions in Carbon and Boron Nitride Moiré Diamanes via Twist Angle Manipulation

TL;DR

This study addresses how interlayer twist angles in diamane-like BNnθ and Dnθ Moiré lattices modulate lattice thermal conductivity and band gap renormalization. It combines density functional theory with active-learning Moment Tensor Potentials to enable large-scale lattice-dynamics and electron-phonon coupling analyses, using both Boltzmann transport equation and Green-Kubo approaches to capture anharmonic effects. The results show that increasing twist angle markedly reduces LTC (by up to ~9× at 27.8°) due to growing structural disorder, and that higher-order phonon interactions are essential for accurate LTC predictions; twist also enhances BGR, with zero-point renormalization strongly amplified by light surface hydrogens. These findings demonstrate that twist-angle and surface passivation can be used as tuning knobs for thermal and electronic properties, with implications for thermoelectrics, microelectronics, and optoelectronics.

Abstract

We have investigated the effect of interlayer twist angle on lattice thermal conductivity (LTC) and band gap renormalization in boron nitride and carbon Moiré diamanes. Moment tensor potentials were used for calculating energies and forces of interatomic interactions. The methods based on the solution of Boltzmann transport equation (BTE) for phonons and the GreenKubo (GK) formula were utilized to calculate LTC. The 20-40 % difference in LTC values obtained with GK and BTE-based methods showed the importance of high-order anharmonic contributions to LTC. Significant reduction (by 4.5 - 9 times) of the in-plane LTC with the twist angle increase caused by the growth of structural disorder was observed in the Moiré diamanes. This growth of disorder also leads to higher band gap renormalization (induced by classical nuclei motion) in the structures with higher twist angles. Significant band gap renormalization values obtained considering the quantum nuclear effects are caused by the high phonon frequencies related to the bonds with hydrogen atoms on the Moiré diamanes surfaces. Understanding of the twist angle effect on LTC and electron-phonon coupling in the Moiré diamanes provides a fundamental basis for manipulating their thermal and electronic properties, making these materials promising for thermoelectrics, microelectronics and optoelectronics.

Figures (14)

• Figure 1: Top and side views of the atomic structure of considered hydrogenated BN and graphene bilayers with twist: BNnAB (a), BNn21.8 (b), BNn27.8 (c), DnAB (d), Dn21.8 (e), Dn27.8 (f) obtained after relaxation with moment tensor potential (MTP).
• Figure 2: Validation of MTP for BNnAB. Comparison of: (a) - forces obtained with DFT and MTP for 1000 snapshots from the trajectory of AIMD performed at 500 K (black dashed line represents an $x=y$ ideal linear fit), (b) - heat capacities and (c) - group velocities obtained with DFT and MTP in the harmonic approximation.
• Figure 3: Validation of MTP for DnAB. Comparison of: (a) - forces obtained with DFT and MTP for 1000 snapshots from the trajectory of AIMD performed at 1000 K (black dashed line represents an $x=y$ ideal linear fit), (b) - heat capacities and (c) - group velocities obtained with DFT and MTP in the harmonic approximation.
• Figure 4: Phonon band structures for the BNn$\theta$ Moiré lattices ((a) - BNnAB, (b) - BNn21.8, (c) - BNn27.8) calculated with MTP and DFT. For convenience of visual perception, the frequency ranges are shown partially. The full graphs with uncut y axes can be found in Fig. S5.
• Figure 5: Phonon band structures for the Dn$\theta$ Moiré lattices ((a) - DnAB, (b) - Dn21.8, (c) - Dn27.8) calculated with MTP and DFT. For convenience of visual perception, the frequency ranges are shown partially. The full graphs with uncut y axes can be found in Fig. S6.