A three-dimensional metal grid mesh as a practical alternative to ITO

Abstract

The development of a practical alternative to indium tin oxide (ITO) is one of the most important issues in flexible optoelectronics. In spite of recent progress in this field, existing approaches to prepare transparent electrodes do not satisfy all of their essential requirements. Here, we present a new substrate-embedded tall (∼350 nm) and thin (∼30 nm) three-dimensional (3D) metal grid mesh structure with a large area, which is prepared via secondary sputtering. This structure satisfies most of the essential requirements of transparent electrodes for practical applications in future opto-electronics: excellent optoelectronic performance (a sheet resistance of 9.8 Ω□(-1) with a transmittance of 85.2%), high stretchability (no significant change in resistance for applied strains <15%), a sub-micrometer mesh period, a flat surface (a root mean square roughness of approximately 5 nm), no haze (approximately 0.5%), and strong adhesion to polymer substrates (it survives attempted detachment with 3M Scotch tape). Such outstanding properties are attributed to the unique substrate-embedded 3D structure of the electrode, which can be obtained with a high aspect ratio and in high resolution over large areas with a simple process. As a demonstration of its suitability for practical applications, our transparent electrode was successfully tested in a flexible touch screen panel. We believe that our approach opens up new practical applications in wearable electronics.

Self-Heating-Induced Deterioration of Electromechanical Performance in Polymer-Supported Metal Films for Flexible Electronics

“…At present, several research efforts are focusing on improving the stretchability of polymer/conductive material composite systems, which is essential for commercializing flexible electronics technologies. Promising methods include the geometrical manipulation of conductive materials (e.g., creating serpentine 44 – 52 , non-planar buckling 15 , 53 – 56 or metal mesh structures 57 – 61 ) and using nanowire networks 62 – 68 . Such methods are based on increasing the heterogeneity of the conductive material.…”

High aspect ratio silver grid transparent electrodes using UV embossing process

“…Much research has been done on alternative materials such as conductive polymers, 7,8 carbon nanotubes, 9,10 graphene films, 11,12 metal nanowires, 13,14 and metal grids. [15][16][17] Among them, metal grids are considered as a promising alternative transparent electrode with high optical transmittance, low sheet resistance, and good flexibility.…”

Template‐Electrodeposited and Imprint‐Transferred Microscale Metal‐Mesh Transparent Electrodes for Flexible and Stretchable Electronics

“…Despite this potential, practical applications of metal‐mesh TEs are still limited because of several generic problems intrinsic to their fabrication procedures. First, the fabrication of regular metal meshes typically uses lithographic patterning to create the mesh pattern for each fabrication cycle, which accounts for a major portion of the fabrication cost and makes these existing approaches low‐yield and not suitable for high‐throughput and large‐volume industrial production. Second, random metal‐mesh TEs utilize various mesh patterning approaches such as electrospun polymer nanofibers and crack‐template methods, where the patterns are randomly distributed and therefore the reproducibility of locating the nanofibers or cracks in specific positions and orientations remains a major challenge.…”