Insight into vertical piezoelectric characteristics regulated thermal transport in van der Waals two-dimensional materials

The urgent demand of extreme(ultra-high/low)thermal conductivity materials is triggered by the high-power device,where exploring the theories and mechanisms of regulating thermal transport properties plays a key role.Herein,we elaborately investigate the effect of vertical(out-of-plane)piezoelectric characteristics on thermal transport,which is historically undiscovered.The different stacking-order(AA and AB)bilayer boron nitride(Bi-BN)in two-dimensional(2D)materials are selected as study cases.By performing state-of-the-art first-principles calculations,it is found that the polarization charge along the out-of-plane orientation ascends significantly with the increasing piezoelectric response in AB stacked Bi-BN(Bi-BN-AB)followed by the enhanced interlayer B–N atomic interactions.Consequently,the amplitude of phonon anharmonicity in Bi-BN-AB increases larger than that in the AA stacked Bi-BN(Bi-BN-AA),resulting in the dramatic weakening of the thermal conductivity by 20.34%under 18%strain.Our research reveals the significant role of the vertical(out-of-plane)piezoelectric characteristic in regulating thermal transport and provides new insight into accurately exploring the thermal transport performance of 2D van der Waals materials.

Electric-controlled tunable thermal switch based on Janus monolayer MoSSe

The high-performance,wide-range tunable thermal switches play a significant role in the thermal management,high-power-density intelligent devices,energy systems,etc.However,traditional thermal switch components,such as thermal diodes,suffer from poor stability,small adjustability,low time efficiency,and difficult implementation.Herein,we propose the superior electric-controlled thermal switch(ECTS)based on Janus monolayer MoSSe.The high-effective and asymmetric regulation of the thermal conductivity driven by electric field demonstrates a wide-range adjustable thermal switch ratio,where the peak value reaches 2.09 under the electric field of 0.04 VÅ^(−1).The underlying mechanism is revealed by electronic structures that the interactions between electrons and phonons are renormalized due to the electric field driving charge density redistribution,which ultimately modulates the phonon anharmonicity.The high-efficiency adjustable ECTS component is expected to provide new inspiration for next-generation thermal management and information processing.