Alkylsilane Self-Assembled Monolayers on Indium Tin Oxide Surface

Abstract

Transparent and conducting indium-tin oxide (ITO) is an attractive substrate for silane attachment. The formation of densely packed self-assembled monolayers (SAMs) on ITO is difficult due to the high roughness and low hydroxyl coverage. The effects of temperature, concentration, and the number of methyl group attached to silane atom on the formation of SAMs were examined. Alkylsilane SAMs were characterized by contact angle measurement, scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS). Contact angle measurements revealed that the adsorption of alkyl silane on ITO surface leads to hydrophobic surface, indicating the formation of SAMs. In addition, STM imaging shows the structural changes in surface morphologies of alkylsilane SAMs before and after the adsorption of alkylsilane molecule. From XPS measurements, we confirmed the formation of Si-O bond of alkylsilane on ITO surface during self-assembly.