Hsiao, Yu ChunYu ChunHsiaoVelusamy, ArulmozhiArulmozhiVelusamyAfraj, Shakil N.Shakil N.AfrajLiu, Jia HaoJia HaoLiuCHENG-LIANG LIUChen, Ming ChouMing ChouChenKao, Hsien MingHsien MingKaoYau, ShuehlinShuehlinYau2023-08-092023-08-092023-09-0115726657https://scholars.lib.ntu.edu.tw/handle/123456789/634484The adsorption of organic molecules on gold electrodes serves as a model to understand the organic/inorganic electrified interface, which is relevant to the study of molecular electronics and organic thin film semiconductors. Our previous study on terthiophene (TT) adsorption on an Au(1 1 1) electrode shows that immersing Au(1 1 1) crystals in a TT ethanol dosing solution installs an ordered TT adlayer on the sample. The current study addresses the adsorption of 3′,4′-bis(hexylthio)-2,2′:5′,2′'-terthiophene (DTDST), a molecule with a TT backbone attached with two thiolhexyl chains, on an ordered Au(1 1 1) electrode. High-quality STM images were obtained to reveal the internal and 2D spatial structures of DTDST admolecules. The potential greatly influenced the organization of DTDST on the ordered Au(1 1 1) electrode. Although the pristine DTDST adlayer was disordered, it transformed into ordered Au(1 1 1) - (3√3 × 9) and (5√3 × 26) structures after applying a potential more negative than 0 V (vs. Ag/AgCl) in 0.1 M H2SO4 and HClO4, respectively. Shifting the potential more positive than 0.25 V resulted in coadsorption of bisulfate anions and restructuring of the DTDST adlayer. High-quality molecular resolution STM images were collected to reveal the azimuthal orientation of the DTDST admolecule on the Au(1 1 1) electrode. The thiolhexyl chains of DTDST admolecules could arrange in such a way that allowed intermolecular van der Waals interactions. Oxidation of adsorbed DTDST molecules to yield oligomers was also revealed by in situ STM.Anion coadsorption | In situ STM | Molecular adsorption | Oligothiophene | Ordered Au(1 1 1) electrode | Substituted terthiophene[SDGs]SDG6journal article10.1016/j.jelechem.2023.1176462-s2.0-85165223695https://api.elsevier.com/content/abstract/scopus_id/85165223695