Ismael Ali, Wang Xintai, Bennett Troy L R, Wilkinson Luke A, Robinson Benjamin J, Long Nicholas J, Cohen Lesley F, Lambert Colin J
Physics Department , Lancaster University , Lancaster , LA1 4YB , UK . Email:
Department of Physics , College of Education for Pure Science , Tikrit University , Tikrit , Iraq . Email:
Chem Sci. 2020 Jun 22;11(26):6836-6841. doi: 10.1039/d0sc02193h. eCollection 2020 Jul 14.
It is known that the electrical conductance of single molecules can be controlled in a deterministic manner by chemically varying their anchor groups to external electrodes. Here, by employing synthetic methodologies to vary the terminal anchor groups around aromatic anthracene cores, and by forming self-assembled monolayers (SAMs) of the resulting molecules, we demonstrate that this method of control can be translated into cross-plane SAM-on-gold molecular films. The cross-plane conductance of SAMs formed from anthracene-based molecules with four different combinations of anchors are measured to differ by a factor of approximately 3 in agreement with theoretical predictions. We also demonstrate that the Seebeck coefficient of such films can be boosted by more than an order of magnitude by an appropriate choice of anchor groups and that both positive and negative Seebeck coefficients can be realised. This demonstration that the thermoelectric properties of SAMs are controlled by their anchor groups represents a critical step towards functional ultra-thin-film devices for future molecular-scale electronics.
众所周知，通过化学改变单分子与外部电极的锚定基团，可以以确定性的方式控制单分子的电导率。在此，我们采用合成方法改变围绕芳香族蒽核的末端锚定基团，并通过形成所得分子的自组装单分子层（SAMs），证明这种控制方法可以转化为金表面的跨平面SAM分子膜。由具有四种不同锚定基团组合的蒽基分子形成的SAMs的跨平面电导率经测量相差约3倍，这与理论预测相符。我们还证明，通过适当选择锚定基团，此类薄膜的塞贝克系数可提高一个多数量级，并且可以实现正、负塞贝克系数。这一证明表明SAMs的热电性能由其锚定基团控制，这是迈向未来分子尺度电子学功能超薄膜器件的关键一步。
