Metal Grid Structures for Enhancing the Stability and Performance of Solution‐Processed Organic Light‐Emitting Diodes

Abstract

AbstractTransparent conducting electrodes (TCEs) are key components of optoelectronic devices where input or output light coupling are central functions—for example, solar cells, light‐emitting diodes, or displays. Indium tin oxide (ITO) has been the TCE of choice for over three decades, and there are few alternatives. The characteristic size of devices made with ITO is often limited to a few centimeters because of the intrinsic sheet resistance. This is an obstacle for scaling thin film photovoltaics and lighting platforms to technologically‐relevant large areas. In this article, the use of metallic micro‐grids is investigated to improve sheet resistance–visible transparency balance of TCEs, resulting in improved performance and stability of organic light‐emitting diodes (OLEDs). Finite element models are used to simulate OLEDs pixels on ITO with metal grids, and these simulations are supported by experimental performance analysis. The reduced potential drop from the presence of grids is shown to lower the Joule heating at the TCE resulting in higher power conversion efficiency and luminosity, as well as improved device stability. Such a strategy could be a very effective way of not only reducing indium usage but also opening new higher resistance TCEs to technological viability.