UCLA researchers in the Department of Materials Science and Engineering have developed a novel composite material made of metal oxide nanoparticles (NPs) and silver nanowires (AgNWs).
For optoelectronic applications, such as liquid crystal devices, light emitting diodes, and thin-film solar cells, there is a need for flexible, transparent conductors that are easily processable under mild and ambient conditions. Current methods to fabricate conducting metal oxide thin films use complex and costly sputtering techniques that are not compatible with high-throughput roll-to-roll processing. Not only are these techniques not viable for flexible device application because the films formed are brittle and crack easily, but the heating involved can damage the underlying organic layers for organic-based optoelectronic devices. Recent research has focused on incorporating AgNW networks into the metal oxide film, but several issues need to be resolved, including the wire-to-wire junction resistance, surface roughness, and gaps between the nanowires, before they can be a practical option.
Researchers led by Professor Yang Yang have developed a novel indium tin oxide (ITO) NP-AgNW composite thin film for transparent, flexible optoelectronic devices. This low temperature technique shows improved wire-to-wire junction conductance, smooth surface morphology, excellent mechanical adhesion and flexibility while maintaining the sheet resistance and transmittance values necessary to replace conventional sputtered ITO thin films. As a proof of concept, ITO NPs were embedded into a AgNW mesh, but this method can be further extended to other metal oxide NPs that are less expensive and more abundant, like aluminum doped zinc oxide and antimony doped tin oxide. This will result in a wide range of conductive metal oxide materials to use for a variety of optoelectronic devices.
Solution processed thin films of these materials have been formed and characterized. Prototype solar cells made from this material have been fabricated and are in the testing stage.
|United States Of America||Issued Patent||9,560,754||01/31/2017||2012-113|
Conductive metal oxides, indium tin oxide, silver nanowire mesh, composite material, transparent conductor, flexible, thin films, solution processable, optoelectronics, solar cells, liquid crystal displays, organic light emitting diodes