Light- and Electric-Field-Induced Switching of Thiolated Azobenzene Self-Assembled Monolayer

Abstract

The reversible isomerization of the azobenzene (AZO) based self-assembled monolayers (SAMs) under external stimuli is the key to their application as molecular switches. To establish the relationship between electronic structure and switching function, AZO and its derivatives with electron donating (NH2) and withdrawing (NO2) terminal groups, respectively, are investigated in the light and electric field triggered configuration changes by using density functional theory (DFT) and molecular dynamics (MD) simulation. Using the modified force field, whose parameters are taken from DFT calculations on the ground and first excited states, the non-equilibrium molecular dynamics simulations show the collective structural transitions in Au(111) surface supported AZO SAMs under ultraviolet–visible light and external electric field stimulation. Along MD trajectories, an index function, S, is then defined to depict the SAM switching dynamics between “on” (S = 1) and “off” (S = 0) states. The charge transfer between ...