Simple and effective cleaning method for RuO2 nanosheet films for flexible transparent conducting electrodes

A critical and practical issue in employing low dimensional nanomaterials as transparent conducting electrodes (TCEs) is the simple and effectual cleaning of the nanomaterials; the presence of contaminants increases the contact resistance at the interface region in practical applications. In this study, various cleaning methods are examined to remove surface contaminants on RuO2 nanosheets (NSs), which are the promising materials for TCEs. The Ar gas cluster ion beam (GCIB) sputtering technique can effectively remove organic surface contaminants, although it has critical drawbacks in the mass production. The simple deionized water treatment can provide satisfactory cleaning performance, which is comparable with that of the Ar GCIB sputtering method. Other methods such as solution-based treatments that use ethanol and chloroform and the heating method do not provide a comparable cleaning performance. The conductive atomic force microscopy demonstrates highly increased conductivity of water-cleaned RuO2 NS films at the nanoscale. This study proposes a practical method for the cleaning of RuO2-based nanomaterials for their application as TCEs and emphasizes their significance of the cleaning process to achieve a higher performance for TCEs based on low dimensional nanomaterials.