Tian Guangjun, Sun Dexian, Zhang Yaogang, Yu Xi
Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Physics and Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, P. R. China.
Angew Chem Int Ed Engl. 2019 Apr 23;58(18):5951-5955. doi: 10.1002/anie.201900731. Epub 2019 Mar 26.
We report an effective modulation of the quantum transport in molecular junctions consisting of aggregation-induced-emission(AIE)-active molecules. Theoretical simulations based on combined density functional theory and rate-equation method calculations show that the low-bias conductance of the junction with a single tetraphenylethylene (TPE) molecule can be completely suppressed by strong electron-vibration couplings, that is, the Franck-Condon blockade effect. It is mainly associated with the low-energy vibration modes, which is also the origin of the fluorescence quenching of the AIE molecule in solution. We further found that the conductance of the junction can be lifted by restraining the internal motion of the TPE molecule by either methyl substitution on the phenyl group or by aggregation, a mechanism similar to the AIE process. The present work demonstrates the correlation between optical processes of molecules and quantum transport in their junction, and thus opens up a new avenue for the application of AIE-type molecules in molecular electronics and functional devices.
我们报道了一种对由聚集诱导发光（AIE）活性分子组成的分子结中量子输运的有效调控。基于密度泛函理论和速率方程方法联合计算的理论模拟表明，具有单个四苯乙烯（TPE）分子的结的低偏置电导可通过强电子 - 振动耦合（即弗兰克 - 康登阻塞效应）被完全抑制。这主要与低能振动模式相关，而这也是AIE分子在溶液中荧光猝灭的起源。我们进一步发现，通过在苯基上进行甲基取代或通过聚集来抑制TPE分子的内部运动，可以提高结的电导，这是一种类似于AIE过程的机制。目前的工作证明了分子的光学过程与其结中的量子输运之间的相关性，从而为AIE型分子在分子电子学和功能器件中的应用开辟了一条新途径。
