搜索

x
中国物理学会期刊

PDE分子器件的大峰谷比负微分电阻效应实现与调控

Implementation and regulation of large peak-to-valley ratio negative differential resistance effect in PDE molecular junction

PDF
导出引用
  • 负微分电阻器件,因其在高速开关、存储及多值逻辑电路中的应用潜力而受到广泛关注。采用密度泛函理论结合非平衡格林函数的第一性原理计算方法,研究了4,4'-(芘-1,6-二基)二苯胺(PDE)分子器件的电子输运性质,探索电极材料与锚定基团对负微分电阻效应的调控机制。研究结果表明:采用金电极的PDE分子器件呈现单调递增的电流-电压特性,而采用锯齿型石墨烯纳米带电极的PDE分子器件呈现显著的低偏压负微分电阻效应,其峰谷电流比可高达3.9×103 。此外,酰胺锚定基团增强分子与电极的π共轭界面耦合,从而产生高电流密度。与之相反,胺基锚定基团引发分子与电极耦合界面的相消干涉,显著降低器件的电导。本工作为高性能负微分电阻器件的开发提供了有价值的理论基础和设计策略。

     

    Developing negative differential resistance (NDR) devices that simultaneously exhibit high conductance and a large peak-to-valley current ratio (PVCR) remains a critical challenge for the realization of molecular-scale logic circuits. The electronic transport properties of 4,4',-(pyrene-1,6-diylbis(ethyne-2,1-diyl)) dianiline (PDE) molecular devices were studied using density functional theory combined with first principles calculations of non-equilibrium Green's functions, exploring the regulatory mechanism of electrode materials and anchoring groups on NDR effects. We first fully optimizes the geometric structure of isolated molecules and electrode cells, with the convergence standard of residual force on each atom set to be less than 0.02 eV/Å. The exchange and correlations were described by the Perdew-Burke-Ernzerhof (PBE) functional under the generalized gradient approximation (GGA). The research results indicate that the PDE molecular devices using gold electrodes has a continuous and high density of states, and strong hybridization with molecular orbitals leads to broadening of the transport peak, exhibiting only monotonically increasing current voltage characteristics. Due to the low density of states near the Fermi level, PDE molecular devices using zigzag graphene nanoribbon (ZGNR) electrodes do not cause hybridization or broadening of molecular orbitals, maintaining the sharp resonance state of molecular orbitals and achieving significant NDR effects. The interface coupling changes caused by anchoring groups can regulate the alignment relationship between the frontier molecular orbitals and the electrode Fermi level, playing a decisive regulatory role in the NDR effect. The amide group forms strong π-π conjugated coupling with the molecular skeleton and ZGNR electrode through carbonyl groups, constructing efficient and continuous electron transport channels. The amino anchoring group triggers destructive interference at the coupling interface between the molecule and the electrode, significantly reducing the conductivity of the device, resulting in a significant attenuation of the peak current of the devices. These findings not only deepen our understanding of the quantum transport mechanism at carbon based molecular interfaces, but also provide clear theoretical guidance and material design paradigms for the future development of low-power, high-performance molecular switches, logic gates, and high-frequency oscillators.

     

    目录

    /

    返回文章
    返回