In this paper,the first-principles method based on density functional theory and non-equilibrium Green's function is used to investigate the modulation of quantum interference and spin transport in N and B atom substituted meta-phenylene(M-OPE)molecular devices.The zero bias spin transmission spectrum of M-OPE molecular device shows that highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)are located at higher energy positions on both sides of the Fermi level,and there is a clear transmission spectrum valley(anti resonance peak)on the right side of the Fermi level.This indicates that M-OPE molecules are typical destructive quantum interference molecular systems.Research has found that N and B atoms replace carbon atoms at positions 1,2,and 3 on the central ring of the molecule,which suppress the original destructive quantum interference of M-OPE molecular device to different extents.The substitution of N and B atoms at position 1 has no effect on the original destructive quantum interference of M-OPE molecular device,while the substitution of N and B atoms at positions 2 and 3 significantly suppresses the original destructive quantum interference of M-OPE molecular device.Therefore,there is a significant difference in the electrical conductivity of devices with N and B atoms at different positions,with the order of electrical conductivity values being N2＞N3＞N1 and B2＞B3＞B1.In this study,it is also found that the spin current value of device with B atom substitution is significantly higher than that of device with N atom substitution.After the substitution of B atom at position 2,the spin current value of the device under negative bias is significantly greater than that under positive bias,exhibiting a significant spin rectification effect.Based on the extended curled arrow rule proposed by O'Driscoll et al.to predict the behavior of quantum interference effects,we explain the physical mechanism by which N and B protons at different positions have different effects on the suppression of quantum interference in M-OPE molecular device.The results of the quantum interference and spin transport regulation of molecular systems by the substitution of B and N atoms can provide theoretical guidance for realizing the further application of heterocyclic aromatic hydrocarbons in molecular electronics.
关键词
第一性原理/密度泛函理论/分子器件/量子干涉/自旋输运
Key words
first principles/density functional theory/molecular device/quantum interference/spin-transport
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