Patterning Indium Tin Oxide Using Self-Assembled Monolayers as Etch Resists for Photovoltaic and Display Devices

In this study, a patterning method of indium tin oxide (ITO) that uses self-assembled monolayers (SAMs), as an etch resist, and mixed organic acid etching solution is presented. In this method, octadecylphosphonic acid (CH3(CH2)17PO3H2) is used for SAM-based surface modification of ITO. Consequently, ultraviolet light (UV)–ozone exposure over a substrate through a mask results in the removal of the SAMs over the exposed regions. The bare and SAM-covered ITO surfaces were characterized by XPS, SEM, and contact angle measurements. The patterned SAMs are used as the etch resist, while the bare region of the ITO is etched by a mixture of oxalic and tartaric acids in a controlled fashion. The method is easy-to-do, cost-effective, high-throughput, and versatile to pattern ITO; and it has a potential application in large-area display and photovoltaic device fabrication as well as pattering of nanostructures.