Work function modification of the (111) gold surface covered by long alkanethiol-based self-assembled monolayers

Abstract

Many recent experimental studies have demonstrated that the deposition of self-assembled monolayers on a metal electrode can significantly modulate its work function and hence charge injection properties in organic-based devices. In this context, we model here by means of Density Functional Theory (DFT) calculations the deposition of long saturated and partially fluorinated alkanethiol chains on the gold (111) surface and explore the shift in the work function while changing the size and degree of fluorination of the molecular backbone in order to contribute to the definition of design rules. Among all the derivatization schemes, only the introduction of a terminal fluoromethyl unit leads to an appreciable change in the work function shift, further accompanied by a reversal of its sign. The results show pronounced odd–even effects with different origins.