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arXiv 1002.0943cond-mat.mes-hallcond-mat.other
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光驱动自组装共轭分子体系的高开关电导率

High on-off conductance switching ratio in optically-driven self-assembled conjugated molecular systems

Kacem Smaali, Stephane Lenfant, Sandrine Karpe, Maitena Ocafrain, Philippe Blanchard, Dominique Deresmes, Sylvie Godey, Alain Rochefort, Jean Roncali, Dominique Vuillaume

摘要:

设计、合成了一种新的偶氮苯-噻吩分子开关,并将其用于金表面自组装膜的制备。“开/关”电导比高达7 × 1 E3(平均值为1.5 × 1 E3)。“开”电导状态被清楚地确定为偶氮苯部分的顺式异构体。高“开/关”比解释光诱导的,配置相关的,在电极-分子界面能量的变化(相对于电极的费米能量的分子轨道的能量位置的变化),除了在隧道势垒长度(分子的长度)的变化。第一性原理的DFT计算表明,更好的离域的前线轨道,以及更强的偶氮苯部分和电极之间的电子耦合的顺式配置的反式。测得的SAM中的分子的光电离截面接近于溶液中偶氮苯衍生物的已知值。

英文摘要:

A new azobenzene-thiophene molecular switch is designed, synthesized and used to form self-assembled monolayers (SAM) on gold. An "on/off" conductance ratio up to 7x1E3 (with an average value of 1.5x1E3) is reported. The "on" conductance state is clearly identified to the cis isomer of the azobenzene moiety. The high "on/off" ratio is explained in terms of photo-induced, configuration-related, changes in the electrode-molecule interface energetics (changes in the energy position of the molecular orbitals with respect to the Fermi energy of electrodes) in addition to changes in the tunnel barrier length (length of the molecules). First principles DFT calculations demonstrate a better delocalization of the frontier orbitals, as well as a stronger electronic coupling between the azobenzene moiety and the electrode for the cis configuration over the trans one. Measured photoionization cross-sections for the molecules in the SAM are close to the known values for azobenzene derivatives in solution.

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