Structural Control and Order of Pentafluorobenzenethiol Self-Assembled Monolayers on Au(111)

Abstract

Self-assembled monolayers (SAMs) prepared by aromatic thiols on gold surfaces have been often used for the fabrication of electronic device applications due to their electronic properties [1,2]. It has been reported that organic SAMs can also be used for tuning the work function of metal electrodes in electronic devices. Especially, the surface modification of metal electrodes by pentafluorobenzenethiol (PFBT) SAMs have been attracted to enhance the charge injection in organic thin-film transistor (OTFT) attracting a great of attention due to the relatively high-effect mobility in several organic materials [3]. To enhance device performance, it is very important to understand molecular-scale features of PFBT SAMs on metal surfaces. In this study, we investigated the surface morphological changes of PFBT SAMs on Au(111) by changing the solution concentration and immersion temperature. Ordered PFBT SAMs can be formed in a 1 mM solution compared to diluted or concentrated solutions. In addition, we found that the molecular ordering was dramatically improved at the solution temperature of 80 °C