光致异构体开关特性的理论研究

Theoretical study on switching characteristic of photoisomers

利用弹性散射格林函数方法,对4,4-二羧基1,2-二苯乙烯分子的两种异构体与金电极构成的单分子结进行了研究.研究表明,该类分子是通过末端羧基化学吸附于金表面的,两种分子结电导特性的差异主要是因为分子与电极的相互作用所致.对每一种分子来说,都存在三种不同的稳定电导值,分别对应着分子末端与金表面的不同接触方式.分子与金表面的相互作用导致分子结电子结构的变化是其电导差异的主要原因.理论结果与实验测量结果符合得较好.

The electron transport properties of the single molecular junctions composed of isomers of 4,4-（ ethene-1,2-diyl） dibenzoic acid and two gold electrodes are investigated systematically using elastic scattering Green~ function method. The conductance characteristics are quite different for the two isomers which can be used to construct molecular switch. Our study shows that the molecules are chemically adsorbed on the gold surface by the terminal carboxyl group. Each molecular junction has three different stable conductances, which correspond to the different contact structures between the molecules and electrodes. The different conductances result mainly from the variation of the electronic structures, caused by the interaction between the molecules and the electrodes. Our theoretical simulation is consistent with the experimental measurement.