Low Jonathan Z, Capozzi Brian, Cui Jing, Wei Sujun, Venkataraman Latha, Campos Luis M
Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA . Email:
Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA . Email:
Chem Sci. 2017 Apr 1;8(4):3254-3259. doi: 10.1039/c6sc05283e. Epub 2017 Feb 28.
Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed with these systems. Through these measurements, we find that increasing the electron affinity of thiophene derivatives, within a family of pentamers, changes the polarity of the charge carriers systematically from holes to electrons, with some systems even showing mid-gap transport characteristics.
噻吩 - 1,1 - 二氧化物（TDO）低聚物具有迷人的电子特性。我们之前通过热电测量表明，当在金电极之间形成单分子结时，随着TDO低聚物长度的增加，电荷载流子会从空穴变为电子。在本文中，我们首次表明，通过改变主链中所包含电子受体的强度，可以调节固定长度的噻吩/TDO低聚物的主导导电轨道。我们使用扫描隧道显微镜断结（STM - BJ）技术，并应用一种最近开发的方法来确定与这些体系形成的单分子结中的主导传输通道。通过这些测量，我们发现，在五聚体家族中，增加噻吩衍生物的电子亲和力会使电荷载流子的极性系统地从空穴变为电子，有些体系甚至表现出带隙中间的传输特性。
