Reduced graphene oxide wrapped core–shell metal nanowires as promising flexible transparent conductive electrodes with enhanced stability

Abstract

Transparent conductive electrodes (TCEs) are widely used in a wide range of optical-electronic devices. Recently, metal nanowires (NWs), e.g. Ag and Cu, have drawn attention as promising flexible materials for TCEs. Although the study of core-shell metal NWs, and the encapsulation/overcoating of the surface of single-metal NWs have separately been an object of focus in the literature, herein for the first time we simultaneously applied both strategies in the fabrication of highly stable Ag-Cu NW-based TCEs by the utilization of Ag nanoparticles covered with reduced graphene oxide (rGO). The incorporation of Ag nanoparticles by galvanic displacement reaction was shown to significantly increase the long term stability of the electrode. Upon comparison with a CuNW reference, our novel rGO/Cu-AgNW-based TCEs unveiled remarkable opto-electrical properties, with a 3-fold sheet resistance decrease (from 29.8 Ω sq to 10.0 Ω sq) and an impressive FOM value (139.4). No detrimental effect was noticed in the relatively high transmittance value (T = 77.6% at 550 nm) characteristic of CuNWs. In addition, our rGO/Cu-AgNW-based TCEs exhibited outstanding thermal stability up to 20 days at 80 °C in air, as well as improved mechanical flexibility. The superior performance herein reported compared with both CuNWs and AgNWs, and with a current conventional ITO reference, is believed to highlight the great potential of these novel materials as promising alternatives in optical-electronic devices.

Large-Area Highly Conductive Transparent Two-Dimensional Ti2CTx Film

“…In fact, Ti 2 CT x film that is plasma treated shows higher transmittance (∼91%) than the previously reported value for 2D Ti 3 C 2 T x film as well as a lower R sh value . Transmittance of our plasma-treated Ti 2 CT x film is comparable to that of pressed rGO (∼91%), but the R sh value of pressed rGO is higher than that of our plasma-treated Ti 2 CT x film. − All of these comparative investigations demonstrate that our Ti 2 CT x film, both as-synthesized and after plasma treatment, performs better than other solution-processed 2D films.…”

“…Since then, various solution processes have been developed to fabricate a large thin film of reduced graphene oxide (rGO), such as in spray coating, spin coating, and dip coating. The rGO film is transparent, with ∼80% transmittance; however, it exhibits high resistance (1–1000 kΩ/sq), probably because of defects induced by oxygen functional groups. − Recently, Kang et al developed a carbon nanotube–graphene composite transparent film with R sh ≈ 533 Ω/sq at 88% transmittance; it has been used as TCE in GaN-based light-emitting diodes . However, there remains a big challenge to develop new materials for large-scale TCE films with improved transmittance and conductivity that can be fabricated at low cost.…”

Failing Forward: Stability of Transparent Electrodes Based on Metal Nanowire Networks

“…A number of studies have demonstrated the incorporation of GO and rGO to MNW‐based transparent electrodes. Thus far, GO/AgNW, [ 38,45–48 ] rGO/AgNW, [ 42–44 ] rGO/CuNW [ 39,40 ] have all been synthesized using various solution‐processing techniques including, but not limited to, spin‐coating, [ 42 ] dip‐treatment, [ 38,40 ] layer‐by‐layer (LbL) coating, [ 48 ] rod‐coating, [ 145 ] electrophoretic deposition (EPD), [ 87 ] and spray‐coating. [ 39,43,45 ] It is interesting to note that both conductive rGO and insulating GO have been used with MNW networks to fabricate TE, with significant improvement of conductivity over bare MNW networks.…”

Emerging Novel Metal Electrodes for Photovoltaic Applications

“…Precise engineering on the growth process for the formation of uniform metal shell is crucial to the stability of transparent electrode with the core–shell NWs. Meanwhile, carbon‐based 2D nanomaterials have also been demonstrated to be good shell materials on both Ag and Cu NWs for the stability improvement of transparent electrode …”