Modification of RuO2 nanosheet microstructure via hydrogen plasma treatment for transparent electrode applications

Abstract

Although monolayer RuO2 nanosheets exhibit semiconducting characteristics, their conductivity must be improved to enable application in transparent electrodes. In this study, RuO2 nanosheet microstructures are modified through H2 plasma treatment to reduce sheet resistance without deteriorating the optical characteristics necessary for flexible transparent electrode applications. Microstructural and chemical changes in the RuO2 nanosheets are observed using monochromator Cs-corrected high-resolution transmission electron microscopy combined with electron energy loss spectroscopy. Single-crystalline RuO2 nanosheets are transformed into nanometer-sized polycrystalline nanosheets. The phase-transformed polycrystalline RuO2 nanosheets contain newly formed defects such as grain boundaries and O vacancies, which result in lower sheet resistances because these defects provide leakage-current paths in the semiconducting RuO2 nanosheets. These defects are located parallel to the direction of light transmission. Consequently, transparency and haze do not significantly deteriorate after H2 plasma treatment. These results indicate that the H2 plasma creates a more stable O-vacancy row which alters the microstructure of the RuO2 nanosheets. Our results demonstrate that H2 plasma treatment can be widely used to fabricate two-dimensional material-based transparent electrodes. © 2024