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本文选取辛烷硫醇分子通过终端S原子化学吸附于一端的Au原子团簇,另一端由碳原子物理吸附于Au原子团簇形成分子结,利用从头计算方法和非弹性散射格林函数理论研究了在三种不同电极接触构型下的该分子的非弹性电子隧穿谱的影响.计算结果表明,电极接触构型对分子体系的非弹性电子隧穿谱有着明显的影响.该工作有利于确定实验中分子电子学器件的电极接触构型.  相似文献   
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Mu-Zhen Li 《中国物理 B》2021,30(12):123302-123302
Thermally activated delayed fluorescence (TADF) molecules have attracted great attention as high efficient luminescent materials. Most of TADF molecules possess small energy gap between the first singlet excited state (S1) and the first triplet excited state (T1) to favor the up-conversion from T1 to S1. In this paper, a new TADF generation mechanism is revealed based on theoretical simulation. By systematic study of the light-emitting properties of SOBF-OMe in both toluene and in aggregation state, we find that the single SOBF-OMe could not realize TADF emission due to large energy gap as well as small up-conversion rates between S1 and T1. Through analysis of dimers, we find that dimers with intermolecular hydrogen bond (H-bond) are responsible for the generation of TADF, since smaller energy gap between S1 and T1 is found and the emission wavelength is in good agreement with experimental counterpart. The emission properties of SOBF-H are also studied for comparison, which reflect the important role of H-bond. Our theoretical results agree ith experimental results well and confirm the mechanism of H-bond induced TADF.  相似文献   
3.
Three kinds of triazine based organic molecules designed for thermally activated delayed fluorescence (TADF) emitters are investigated by first-principles calculations. An optimal Hartree-Fork (HF) method is adopted for the calculation of energy gap between the first singlet state (S1) and the first triplet state (T1). The natural transition orbital, the electronhole (e-h) distribution and the e-h overlap diagram indicate that the S1 states for the three systems include both charge-transfer and some localized excitation component. Further quantitative analysis of the excitation property is performed by introducing the index Δr and the integral of e-h overlap S. It is found that symmetric geometry is a necessary condition for TADF emitters, which can provide more delocalized transition orbitals and consequently a small S1-T1 energy gap. Artful inserting aromatic groups between donors and acceptors can significantly enhance the oscillator strength. Finally, the energy state structures calculated with the optimal HF method is presented, which can provide basis for the study of the dynamics of excited states.  相似文献   
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在杂化密度泛函理论的基础上,利用弹性散射格林函数方法研究了烷烃硫醇系列分子的电输运性质,并同实验结果进行了比较。研究结果表明,在低的外加偏压下,烷烃硫醇分子电流值随着分子链长度的增加而指数减小,其衰减常数约为1.41/CH2,且衰减常数基本上与外加偏压值的大小无关。分子末端原子与探针的距离具有较大地自由度,不同的接触距离导致了分子的电流值有较大地差别。  相似文献   
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本文基于第一性原理,研究了八个热活化延迟荧光分子的性质,揭示了基团供电子能力对分子几何构型、跃迁属性以及反系间窜越过程的影响.研究结果表明,对于咔唑和氧杂蒽酮组成的一类分子的最低三重激发态(T1)而言,供体基团的二苯胺取代,几乎不会改变供体和受体之间的夹角,但却可以减小供体和受体间的键长.基团供电子能力越强,最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)间的轨道重叠度越小,最低单重激发态S1和T1之间的能差(△ES1-T1)越小.此外,供体基团上增加二苯胺能够增加HOMO的离域性,而且能够进一步地减小△ES1-T1.通过计算S1和T1之间的旋轨耦合系数(Hso),发现(<S1so|T1>2)/(△ES1-T12)数值越大,反系间窜越速率越大.计算表明八个分子都可能是高效的热活化延迟荧光分子.本文提出了一条高效热活化延迟荧光分子的设计策略,即分离HOMO和LUMO的分布和增加HOMO的离域性能够有效地减小S1-T1能差.  相似文献   
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