Abnormally Strong Electron–Phonon Scattering Induced Unprecedented Reduction in Lattice Thermal Conductivity of Two-Dimensional Nb₂C

Abstract

In most materials the electron–phonon (e-p) scattering is far weaker than phonon–phonon (p-p) scattering, and the e-p scattering is usually proportional to the e-p coupling strength. Here, we report strong e-p scattering but low e-p coupling strength in two-dimensional­(2D) Nb2C by first-principles calculations. Moreover, the intensity of e-p scattering is close to that of p-p scattering at 300 K in sharp contrast to normal cases. This abnormal e-p scattering is understood by a specific feature that the energy difference between occupied and empty electron states near the Fermi level is in the order of the characteristic phonon energy. By calculating the phonon transport property of 2D Nb2C, we show that this strong e-p scattering can result in great reduction in the lattice thermal conductivity.Our work also highlights a new way for searching novel 2D materials with low lattice thermal conductivity.

Tuning thermoelectric efficiency of monolayer indium nitride by mechanical strain

“…Electronphonon coupling is substantial in highly doped semiconductors and metals due to possessing enough electron states around the Fermi surface. 73 Accordingly, in h-InN, this interaction is not expected to be strong. The suggested approach is applied to various 2D systems including Group III-N monolayers, 64,74 and also tested on prototype materials such as graphene.…”

Impact of Electron-Phonon Interaction on Thermal Transport: A Review

“…In addition to carrier concentrations, band structures also play an important role in determining the strength of electron-phonon scatterings. It is found in Nb2C that the intensity of electron-phonon scatterings is comparable to that of phonon-phonon scattering at 300 K [60], which was attributed to the high electron DOS around the Fermi level and the special feature that the energy difference between occupied and empty electron states is on the same order of the characteristic phonon energy, making the momentum and energy conservation conditions more easily satisfied. Liu et al also provide an example to illustrate how band structures influence the EPI process, where the effect of EPI on phonon transport in 2D MoS2 and PtSSe is compared [61].…”

“…Nb2C [60], monolayer MoS2 and PtSSe [61]. Compared with phonon scattering by electrons in three-dimensional bulk materials, this scattering mechanism in two-dimensional (2D) systems is expected to behave qualitatively differently because of different electron and phonon dispersion relations, the reduced dimensionality and the associated scattering phase space, prominent normal phonon-phonon scatterings and potential hydrodynamic phonon transport [15], and new crystal symmetries and the corresponding scattering selection rules [62].…”

Passively mode locked thulium and thulium/holmium doped fiber lasers using MXene Nb2C coated microfiber

“…Being in the family of MXene, niobium carbide (Nb 2 C) has received extensive research attention in the last few years, due to its unique physical and chemical properties that are valuable in various applications 74 . Theoretically, it has been predicted that Nb 2 C demonstrates a great reduction of lattice thermal conductivity resulted from the abnormal electron–phonon scatterings with intensities close to that of phonon–phonon scatterings 75 . In a study conducted by Lin et.…”