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The Analysis Of Charge Transport Mechanism In Molecular Junctions Based On Current-voltage Characteristics
Published 2020 · Chemistry
Abstract We report here a theoretical model study of the current-voltage (I-V) characteristics of tunneling and hopping transport in molecular junctions. We found that the I-Vs of the two types of transport have very different shape characteristics. The I-V in tunneling transport is in near-linear relation at low bias, while is exponential for the hopping transport. The current in hopping transport thus can span a much wider range at semi-logarithm scale than tunneling transport, which can be used as an intuitive guide in analyzing the transport mechanism. The idea is supported by series of experimental studies reported before by Frisbie et al. where a clear I-V characteristic change can be seen when transport mechanism changed from tunneling to hopping. The two theoretical models were further used to fit the reported experimental I-V data, and we found that the transport mechanism obtained by the model is in consistence with the experimental conclusion. Moreover, our method also revealed the coexistence of two transports during the tunneling-to-hopping transition, and the contribution of the two channels to the current is bias dependent. Our research thus provides a new powerful theoretical method for the study of charge transport mechanism in molecular junctions.