Elucidation of Electron Transport Properties of Small Gold Nanoparticle Superlattices Connected with Parallel and Perpendicular π-Conjugated System

当小的Au纳米颗粒用作室温下操作的单电子器件的单电子岛时，有机配体的隧穿电阻和量子电阻应该是低的。我们发展了一种简单的方法来控制Au纳米粒子的尺寸，甚至可以使用隧道电阻为~MΩ的己烷。为了进一步降低隧穿电阻，在Au纳米粒子表面以面配位的方式吸附了各种大环π共轭配体。非常有趣的是，我们发现了非常独特的光学性质以及由于π轨道和Au轨道之间的电子相互作用而导致的隧穿电阻的急剧减小。我们还成功地进行了Au_2团簇的大规模合成<25>。另一方面，发现小的Au纳米颗粒在室温下表现出单电子传输性质和库仑阻塞。

When the small Au nanoparticles are used as single-electron islands for single-electron devices operated at room temperature, the tunneling resistance of organic ligands should be low as well as the quantum resistance. We developed a facile method to control the size of Au nanopaticles even by using hexanethiol with the tunneling resistance of～MΩ. For further reduction of the tunneling resistance, various macrocyclic π-conjugated ligands were adsorbed on the Au nanoparticles in a face-coordination fashion. Very interestingly, we found quite unique optical properties as well as drastic reduction of the tunneling resistance due to the electronic interaction beween the π-orbitals and Au orbitals. We also succeeded in the large-scale synthesis of Au_<25> clusters. On the other hand, small Au nanoparticles were found to exhibit single-electron transport property and Coulomb blockade at room temperature.