Room Temperature Wafer-Scale Synthesis of Highly Transparent, Conductive CuS Nanosheet Films via a Simple Sulfur Adsorption-Corrosion Method

Abstract

The development of highly conductive electrodes with robust mechanical durability and clear transmittance in the visible to IR spectral range are of great importance for future wearable/flexible electronic applications. In particular, low resistivity, robust flexibility, and wide spectral transparency have a significant impact on optoelectronic performance. Herein, we introduce a new class of covellite copper monosulfide (CuS) nanosheet films as a promising candidate for soft transparent conductive electrodes (TCE). An atmospheric sulfur adsorptioncorrosion phenomenon represents a key approach in our work for the achievement of wafer-scale CuS nanosheet films through systematical control of the neat Cu layer thickness ranging from 2 nm to 10 nm multilayers at room temperature. These nanosheet films provide outstanding conductivity (~ 25 Ω sq -1 ) and high transparency (> 80 %) in the visible to infrared region as well as distinct flexibility and long stability under air exposure, yielding a high figure-of-merit (FoM) (~ 60) that is comparable to that of conventional rigid metal oxide material-based TCEs. Our unique room temperature synthesis process delivers high quality CuS nanosheets on any arbitrary substrates in a short time (< 1 min) scale, thus guaranteeing the widespread use of highly producible and scalable device fabrication.

Electrode‐Induced Self‐Healed Monolayer MoS2 for High Performance Transistors and Phototransistors

“…The Raman spectrum of CuS shows distinct Raman vibrational modes at around 263.8 and 471.3 cm -1 , which correspond to the lattice CuS and SS stretching of covellite, respectively (Figure S2, Supporting Information). [19] The MoS 2 /CuS transistor was fabricated by transferring the CuS nanosheet films onto the MoS 2 monolayer (Figure 1c). Polystyrene (PS) films were used to detach the CuS/PS films in deionized (DI) water, [20,21] and the films were dried in air to completely remove water molecules to achieve clean interface between the CuS electrodes and MoS 2 monolayers.…”

“…Note that the Cu metal films were directly exposed to H 2 S gas under ambient condition at room temperature to synthesize CuS nanosheet films as we previously reported. [ 19 ] Reactive H 2 S gases adsorb onto Cu surface and donate sulfur ions, and copper corrosion reaction with adsorbed sulfur ions leads to the formation of covellite CuS structure. In spite of the ultrathin thickness of CuS, its electrical properties are known to be as good as indium tin oxide (see Figure S1, Supporting Information, for electrical data).…”

“…In spite of the ultrathin thickness of CuS, its electrical properties are known to be as good as indium tin oxide (see Figure S1, Supporting Information, for electrical data). [ 19 ] The synthesized CuS nanosheet films possess covellite structure (JCPDS card No. 78–0877) as confirmed by the XRD analysis (Figure 1b).…”

“…The Raman spectrum of CuS shows distinct Raman vibrational modes at around 263.8 and 471.3 cm –1 , which correspond to the lattice CuS and SS stretching of covellite, respectively (Figure S2, Supporting Information). [ 19 ]…”

Transparent, Conducting Self‐Assembled CuS Nanostructures at and beyond Liquid‐Liquid Interface and their Electrocatalytic Properties

“…CuS shows photo/electrocatalytic activity and offers high transparency in the visible region when the film thickness is low (<50 nm). Transparency decreases with increasing thickness [11] . As thin films have a less effective surface area, designing self‐supported vertically aligned CuS thin films can show both high surface area (necessary for catalysis) and maintain decent transparency simultaneously.…”