Modeling of self-assembled monolayers (SAMs) of Octadecanethiol and Hexadecanethiol on gold (Au) and silver (Ag)

Abstract

This work proposes a modeling of self-assembled monolayers (SAMs) to assess the quality of SAM layers in terms of their leaky behavior. In the modeling, electrochemical impedance spectroscopy (EIS) and a conceptual and simplified resistance-resistance-capacitance (RRC) electrical model from an electrochemical setup were demonstrated. Based on the model, Matlab-based simulation was carried out to find out the suggestive low frequency measurement for analyzing the defective monolayers. Finally, the developed electrical model facilitated the interpretation of the EIS spectra measured in the range of 10 Hz to 100 kHz and provided the capacitance, resistance and thickness of the monolayer. Thus the proposed model could be considered as a powerful tool to characterize the defective SAMs, which was very specific to determine the resistive behavior of the self-assembled monolayers prepared for shorter adsorption time. Keywords: Self-assembled monolayers (SAMs), Octadecanethiol (ODT), Hexadecanethiol (HDT, Impedance, Capacitance of the SAM (CSAM), Resistance of the SAM (RSAM)