Cloaking Contacts on Large‐Area Organic Light‐Emitting Diodes

Abstract

Metallic contact grids on top of large‐area organic light‐emitting diodes (OLEDs) are important for laterally homogenized current spreading leading to a lower series resistance and reduced large‐scale brightness gradients. However, the contacts are also visible by unwanted shadows, i.e., by spatially inhomogeneous Lambertian light emission. In this paper, inspired by recent work on diffuse‐light core–shell invisibility cloaking, a practical tailored distribution of light scattering centers is designed on top of an OLED to homogenize its light emission. Numerical solutions of the light‐diffusion equation as well as Monte Carlo ray‐tracing simulations are presented. The blueprint is verified by experiments on a scaled‐up model structure. The contacts can be made “invisible” in emission while maintaining large light throughput.