Song Dian, Li Jie, Liu Kun, Guo Junnan, Li Hui, Okulov Artem
School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China.
Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, China.
Molecules. 2023 Dec 7;28(24):7994. doi: 10.3390/molecules28247994.
CN-ring-based molecular chains were designed at the molecular level and theoretically demonstrated to show distinctive and valuable electron transport properties that were superior to the parent carbonaceous system and other similar nanoribbon-based molecular chains. This new -type molecular chain presented an exponential attenuation of the conductance and electron transmission with the length. Essentially, the molecular chain retained the electron-resonant tunneling within 7 nm and the dominant transport orbital was the LUMO. Shorter molecular chains with stronger conductance anomalously possessed a larger tunnel barrier energy, attributing to the compensation of a much smaller HOMO-LUMO gap, and these two internal factors codetermined the transport capacity. Some influencing factors were also studied. In contrast to the common O impurity with a tiny effect on electron transmission of the CN rings chain, the common H impurity clearly improved it. When the temperature was less than 400 K, the electron transmission varied with temperature within a narrow range, and the structural disorder deriving from proper heating did not greatly modify the transmission possibility and the exponentially decreasing tendency with the length. In a non-equilibrium condition, the current increased overall with the bias but the growth rate varied with size. A valuable negative differential resistance (NDR) effect appeared in longer molecular chains with an even number of big carbon-nitrogen rings and strengthened with size. The emergence of such an effect originated from the reduction in transmission peaks. The conductance of longer molecular chains was enhanced with the voltage but the two shortest ones presented completely different trends. Applying the bias was demonstrated to be an effective way for CN-ring-based molecular chains to slow down the conductance decay constant and affect the transport regime. CN-ring-based molecular chains show a perfect application in tunneling diodes and controllable molecular devices.
基于碳氮环的分子链在分子水平上进行了设计，并在理论上证明具有独特且有价值的电子传输特性，优于母体碳质体系和其他类似的基于纳米带的分子链。这种新型分子链的电导和电子传输随长度呈指数衰减。本质上，分子链在7纳米范围内保持电子共振隧穿，主导传输轨道为最低未占分子轨道（LUMO）。电导较强的较短分子链反常地具有较大的隧穿势垒能量，这归因于较小的最高已占分子轨道与最低未占分子轨道能隙的补偿，这两个内部因素共同决定了传输能力。还研究了一些影响因素。与对碳氮环链电子传输影响微小的常见氧杂质相比，常见氢杂质明显改善了电子传输。当温度低于400 K时，电子传输在窄范围内随温度变化，适当加热引起的结构无序并没有极大地改变传输可能性以及随长度呈指数下降的趋势。在非平衡条件下，电流总体上随偏压增加，但增长率随尺寸变化。在具有偶数个大碳氮环的较长分子链中出现了有价值的负微分电阻（NDR）效应，且随尺寸增强。这种效应的出现源于传输峰的减少。较长分子链的电导随电压增强，但最短的两条呈现完全不同的趋势。已证明施加偏压是减缓基于碳氮环分子链电导衰减常数并影响传输机制的有效方法。基于碳氮环的分子链在隧道二极管和可控分子器件中显示出完美的应用前景。
