Anomalous Optoelectric Properties of an Ultrathin Ruthenium Film with a Surface Oxide Layer for Flexible Transparent Conducting Electrodes

Abstract

The growing industrial demand for flexible optoelectric devices has led to intensive researches on highly flexible transparent electrode materials such as graphene, reduced graphene‐oxide (r‐GO), Ag‐nanowire, and 2D metal oxides. However, except Ag‐nanowire, transparent electrode materials having optoelectric properties comparable to that of indium–tin–oxide (ITO) have not yet been developed. In this study, an ultrathin ruthenium film with a ruthenium oxide (RuO2) subsurface layer has been introduced as a flexible transparent electrode. The metallic Ru thin film is fabricated from a RuO2 nanosheet using a layer‐by‐layer coating technique, followed by thermal reduction. The thin film (≈6 nm) reveals comparable sheet resistance and transmittance as that of conventional ITO electrodes. The high transmittance (≈79%) of the metal thin film in the visible range is attributed to the presence of an oxide subsurface layer which acts as antireflection. The Ru film (with oxide subsurface layer) with figure‐of‐merit ≈3.4 × 10−4 Ω−1 shows the best performance among the thin films fabricated using a wet‐chemistry process with 2D nanosheets including graphene, r‐GO, and other metal oxides. In addition, the high mechanical flexibility of Ru thin film makes it next‐generation flexible transparent conducting electrodes, beyond graphene, r‐GO, and 2D metal oxides.

Flexible Antireflection Coatings with Enhanced Durability and Antifogging Properties

“…Nanochains outperform nanospheres in both AR and mechanical properties of the resulting iARCs, due to their lower packing density and mechanical interlocking between the nanochains. These nanochain-based iARCs maintain their AR properties even after an abrasion test and more than 1000 mechanical bending cycles, with a bending radius as small as 5 cm; this condition corresponds to a bending strain of 1%, commonly experienced by flexible displays and devices. − Leveraging the gradient formed during the infiltration of polydisperse polymers into disordered packings of hollow silica nanochains, we fabricate graded iARCs with broadband AR properties across the visible spectrum. These iARCs also exhibit an antifogging capability due to their superhydrophilicity and maintain exceptional mechanical robustness and post-polymer infiltration.…”

Thermal and Chemical Phase Engineering of Two-Dimensional Ruthenate

“…100–300 F g –1 ) synthesized via chemical exfoliation. , In addition, the monolayer structure with surface-exposed O-Ru-O bonds is an ideal geometry for the efficient use of precious Ru for catalysts. These advantages have motivated a number of studies for electronic − and energy applications. − …”