UV induced formation of transparent Au–Ag nanowire mesh film for repairable OLED devices

Abstract

The next generation of optoelectronic devices requires transparent conductive electrodes to be flexible, cheap, and compatible with large scale manufacturing processes. Indium Tin Oxide (ITO) electrodes are often used due to their superior transparency and conductance, however they are brittle, expensive and their fabrication requires vacuum conditions which restrict scale-up. One possible alternative to the traditional ITO electrode is the metal nanowire mesh (MNWM) electrode, which is transparent, conductive, flexible and easy to produce. In this work we present the preparation and characterization of a simple organic light emitting diode (OLED) device based on a transparent electrode made of ultrathin MNWM and a comparison to an ITO based device. We have found that MNWM electrodes offer a suitable alternative to ITO electrodes in OLED devices. We have also found that the failure rate for devices due to short circuits between the top and bottom electrodes was smaller in MNWM based devices compared to ITO based devices since the MNWM devices could be repaired to present normal OLED behavior by selectively burning the nanowires forming the short. The ability to ''heal'' organic devices presents an important advantage and also allows for future uses in applications such as roll to roll printing.

Transparent electrodes for organic optoelectronic devices: a review

“…18,228,229 Although many metal nanostructures, such as copper, 230,231 gold, 232,233 and cupronickel, 234 have been demonstrated with promising properties and possibility as electrodes, Ag NWs have been the focus of research in this area due to the excellent electrical properties of bulk Ag materials and the synthesis scalability of Ag NWs. Ag NWs with a typical diameter of 20 to 40 nm and length of >20 μm dispersed in water or organic solvents are now commercially available.…”

Development of Au-Ag nanowire mesh fabrication by UV-induced approach

“…This amount is tremendously lesser than that suggested in [32] -1minute of washing in 10ml of ethanol:water solution.…”

“…Samples were initially prepared employing the method as explained in [32], and using the same way of washing the slides with ethanol:water solution as conveyed therein. These samples were then observed under a Scanning Electron Microscope, or SEM (Hitachi, SU6600), & Energy Dispersive X-Ray Spectroscope, or EDS (Horiba, EDS EX350).…”

“…The thinfilms of these nanowires were having high transmitivity of 90-95%. However, the proposed method in [32] needs some alterations -the ethanol:water solution required to wash off excess CTAB actually washes away the NWs formed, and thus a quantity preferably not more than 0.5ml for 4 sq.cm. area of the substrate, needs to be employed.…”

“…This paper deals with a similar approach for fabricating Au-Ag nanowires (NWs), but the seeds are not introduced for the initiation of the nanowire-growth. Instead, UV light is employed for the formation of gold-nanoparticles, directly in the chemical solution -an approach, first reported by Gill Markovich et al [32]. The procedure requires cheaper installation, and less than an hour for the fabrication of Au-Ag NW mesh thinfilms.…”