Mechanism of electric field regulation of thermal transport properties of monolayer borophene
MENG Jin
LI Nan
YANG Zhonghua
ZHOU Bo
Abstract：[Objective]The anisotropy and isotropy of thermal transport are fundamental properties of materials,which are crucial in practical applications.However,current research on tuning the transition from anisotropic to isotropic thermal transport primarily relies on structural design or material processing.The methods are time-consuming,costly,and irreversible,which severely limits flexibility of the properties in practical applications.Therefore,a scheme was proposed to regulate the thermal transport properties of two-dimensional borophene by using an external electric field,aiming to explore a new method for stable and reversible regulation without altering the atomic structure of the material.[Methods]First-principles calculations were combined with the phonon Boltzmann transport equation to systematically investigate the effect of an external electric field on the thermal transport properties of borophene.The underlying physical mechanisms were revealed systematically by quantifying the regulatory effects of electric field strength on phonon lifetime,thermal conductivity,and anisotropy,and the ratio of thermal conductivities in two in-plane directions(x and y directions)was used as an indicator of the changes in anisotropy.[Results]Under the influence of an external electric field,the lattice thermal conductivity of borophene in both in-plane directions increases significantly and gradually peaks with a maximum enhancement factor of 2.82.Meanwhile,the intrinsic anisotropy ratio is boosted to a maximum value of 2.13.As the electric field strength increases further,the thermal conductivity drops rapidly,and the anisotropy exhibits oscillating decay.When the electric field strength increases to 0.4 V/Å,the thermal conductivity is dramatically reduced.Nearly isotropic thermal transport characteristics are demonstrated when the anisotropy ratio decreases to 1.25.Further analysis reveals that this abnormal transition from anisotropic to isotropic thermal transport is fundamentally due to the large enhancement and suppression of phonon lifetime at moderate and high electric field strengths,respectively,which acts as an amplifying or reducing factor for thermal conductivity.[Conclusion]Phonon lifetime can be modulated by an external electric field,achieving stable and reversible precise regulation of the thermal transport properties of two-dimensional borophene without altering its atomic structure.This approach effectively overcomes the limitations of traditional regulation methods and provides a new theoretical and technical pathway for the precise regulation of phonon thermal transport anisotropy,showing a broad application prospect in such fields as thermal management of nanoelectronics and thermoelectric energy conversion.
Keywords：two-dimensional borophenelattice thermal conductivityfirst-principlesBoltzmann transport equationphononelectric field regulationisotropyanisotropy
Publication Date：2025-09-25
Online Publishing Date：2025-10-31(First online date of this platform, not the publication date of the document)
Pages：7( 649-655 )