Flexible transparent conductor free of reflection and scattering
An effort is being made to search alternative transparent conductor materials that could replace indium-tin-oxide (ITO), especially for device flexibility. While the scientific community has investigated materials such as Al-doped ZnO, carbon nanotubes, metal nanowires, ultra-thin metals, conducting polymers and most recently graphene, none of these have been able to present optimal properties that would make these replace ITO.
Ultra-thin metal films have been shown to present very low resistance, although their transmission is also low, unless anti-reflection undercoat and overcoat layers are added to the structure. ICFO-The Institute of Photonic Sciences researchers Rinu Abraham Maniyara, Vahagn K. Mkhitaryan, Tong Lai Chen and Dhriti Sundar Ghosh, under the guidance of Valerio Pruneri, ICREA Prof. at ICFO, have developed a room temperature processed multilayer transparent conductor optimising the anti-reflection properties to obtain high optical transmissions and low losses, with large mechanical flexibility properties.
In their study, they applied an Al-doped ZnO overcoat and a TiO2 undercoat layer with precise thicknesses to a highly-conductive silver ultra-thin film. By using destructive interference, the researchers showed that the proposed multilayer structure could lead to an optical loss of approximately 1.6 per cent and an optical transmission greater than 98 per cent in the visible.
The study shows the potential that this multilayered structure could have in technologies that aim at efficient and flexible electronic and optoelectronic devices.