Unraveling Thermoelectric Properties of 2D Nb2XSe2 (X = B, C, N) via First-principles Calculations

2026-04-01

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Chen, Lanli *

DOI：10.1007/s13538-026-02064-0

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Based on first-principles calculations combining density functional theory (DFT) and the Boltzmann transport equation, this study systematically investigates the thermoelectric properties of two-dimensional Nb2XSe2 (X = B, C, N) materials. The electronic structure near the Fermi level exhibits strong hybridization between Nb d-orbitals and X/Se p-orbitals, coexisting with heterogeneous bonding characteristics-polar covalent Nb-Se bonds and delocalized ionic Nb-B/C/N bonds. Phonon transport analysis reveals that, with increasing atomic number of X, the enhanced hybridization between antibonding and bonding states elevates lattice anharmonicity, leading to an increase in the acoustic-mode Gr & uuml;neisen parameter |gamma| from 1.9 to 3.1 and a significant reduction in lattice thermal conductivity from 4.13 to 0.30 W/(m & centerdot;K). Thermoelectric optimization results demonstrate that p-type doped Nb2CSe2 simultaneously achieves the maximum Seebeck coefficient (-70.4 & micro;V & centerdot;K- 1) and power factor (13.4 mW & centerdot;m- 1 & centerdot;K- 2), yielding a peak zT value of 0.92 at room temperature. In contrast, the zT values of all three compounds under n-type doping are approximately 0.04-0.38. The realization of high zT values relies on low lattice thermal conductivity as the foundation, along with the synchronous enhancement of electronic transport properties to achieve a synergistic balance between electron and phonon transport.

Keywords:

LATTICE THERMAL-CONDUCTIVITY

TOTAL-ENERGY CALCULATIONS

MOLECULAR-DYNAMICS

PERFORMANCE

TRANSPORT

POWER

MONOLAYER

EFFICIENT

Unraveling Thermoelectric Properties of 2D Nb2XSe2 (X = B, C, N) via First-principles Calculations

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