Carlotti Marco, Soni Saurabh, Kovalchuk Andrii, Kumar Sumit, Hofmann Stephan, Chiechi Ryan C
Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K.
ACS Phys Chem Au. 2022 May 25;2(3):179-190. doi: 10.1021/acsphyschemau.1c00029. Epub 2022 Jan 12.
This paper describes a simple model for comparing the degree of electronic coupling between molecules and electrodes across different large-area molecular junctions. The resulting coupling parameter can be obtained directly from current-voltage data or extracted from published data without fitting. We demonstrate the generalizability of this model by comparing over 40 different junctions comprising different molecules and measured by different laboratories. The results agree with existing models, reflect differences in mechanisms of charge transport and rectification, and are predictive in cases where experimental limitations preclude more sophisticated modeling. We also synthesized a series of conjugated molecular wires, in which embedded dipoles are varied systematically and at both molecule-electrode interfaces. The resulting current-voltage characteristics vary in nonintuitive ways that are not captured by existing models, but which produce trends using our simple model, providing insights that are otherwise difficult or impossible to explain. The utility of our model is its demonstrative generalizability, which is why simple observables like tunneling decay coefficients remain so widely used in molecular electronics despite the existence of much more sophisticated models. Our model is complementary, giving insights into molecule-electrode coupling across series of molecules that can guide synthetic chemists in the design of new molecular motifs, particularly in the context of devices comprising large-area molecular junctions.
本文描述了一个简单模型，用于比较不同大面积分子结中分子与电极之间的电子耦合程度。由此产生的耦合参数可直接从电流-电压数据中获得，或从已发表的数据中提取，无需拟合。我们通过比较40多个由不同分子组成且由不同实验室测量的不同结，证明了该模型的通用性。结果与现有模型一致，反映了电荷传输和整流机制的差异，并且在实验限制排除更复杂建模的情况下具有预测性。我们还合成了一系列共轭分子线，其中嵌入的偶极子在分子-电极界面处系统地变化。由此产生的电流-电压特性以现有模型无法捕捉的非直观方式变化，但使用我们的简单模型会产生趋势，提供了难以用其他方式解释或无法解释的见解。我们模型的实用性在于其具有通用性，这就是为什么尽管存在更复杂的模型，像隧穿衰减系数这样简单的可观测值在分子电子学中仍然被广泛使用。我们的模型具有互补性，能够深入了解一系列分子中的分子-电极耦合，从而可以指导合成化学家设计新的分子基序，特别是在包含大面积分子结的器件背景下。
