Model Study on the Ideal Current-Voltage Characteristics and Rectification Performance of a Molecular Rectifier under Single-Level-Based Tunneling and Hopping Transport

As a fundamental unit of molecule-based electronics, a molecular rectifier is one of the most widely studied molecular devices, of which the ideal current-voltage (I-V) characteristics based on a theoretical model is of great importance for its property modulation and performance improvement. In this work, we performed a systematic and comparative theoretical model study on the I-V characteristics and rectification performance of the molecular rectifier based on a single-level model under two well-recognized transport mechanisms, tunneling and hopping, using the Landauer formula and Marcus theory, respectively. We identified distinct origins and performance of rectification by the two transport mechanisms and found that hopping transport can afford a much higher rectification than tunneling. The effects of the key physical parameters on the device characteristics were extensively evaluated, like the voltage division factor, energy barrier, coupling to the electrode, and temperature, which provided guidelines for the rectifier performance modulation and device design. Based on the two models, we further analyzed the reported experimental data and revealed the application of the models on the mechanism study of the molecular rectifier.