These studies are based on self-forming templates consisting of interconnected crack networks formed by desiccation of thin colloidal layers, where the cracks are deposited with a desired metal (any material). Once the template is washed away, a network of the deposited metal is obtained on the substrate. The critical steps which have been addressed during optimization of the crack template are: unbroken connectivity, no residual layer underneath the crack, nearly uniform width and overall uniformity over large areas, all these factors being aimed at large area fabrication strategy in lieu of the laborious lithography steps. Valuable insights have been gained by carrying out theoretical studies on desiccating layers. Using ordinary glass as substrate, an overlaying metal wire network can serve as a transparent conductor, an aspect most sought after in the literature as a replacement for the existing indium-tin-oxide coatings. Transparent conductors made from this invention, provide affordable solutions besides adding many novel features. Using nanomesh electrodes, many optoelectronics and optoelectrical devices have been fabricated including touchscreens, touchpanels, OLEDs, EMI shields and smart windows. Besides conventional applications, the recipe has been employed to realize many other devices which are otherwise not transparent such as transparent strain sensor, optical gratings, and supercapacitors. The activity has resulted in several publications, a few patent applications (including of USA) and in addition, has led to new projects involving abroad universities (Purdue, USA and Bayreuth, Germany) as well as industry partners (Papierfabrik Louisenthal GmbH, Tata Steel and HHV). This is a fine example of a laboratory invention maturing through technology translation to become a product.
(a) Fabrication of a transparent conducting layer made of metal wire network.
(b) Few meter long PET plastic layer coated with an invisible Al wire network (45 ohm/square), produced roll-to-roll at a semi-pilot plant, as part of a Indo-German project activity. Visible transparency (~85%). The nominee (on the right) is seen along with the German collaborators.
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