Recent progress in the development of materials and devices for single-doped white devices is presented with a particular focus on the development of platinum complexes exhibiting excimer emission. White organic light emitting diodes (WOLEDs) are strong candidates for the next generation of solid-state lighting, yet many of the best devices generate white light using multiple emitters embedded in a comparably complex device structure, raising the difficulty of consistently manufacturing these devices at a low cost and leading to challenges in color stability. These problems can be overcome by fabricating excimer-based WOLEDs, which construct a broad spectrum from a single emitter using blue monomer emission and red excimer emission. Through rational emitter design, the color quality and device efficiencies have steadily improved with recent achievements of external quantum efficiencies over 20% and a color rendering index greater than 80. Furthermore, recent applications of tetradentate platinum complexes for single-doped WOLEDs have yielded devices with a performance superior to many state-of-the-art multilayer WOLEDs as well as promising device operational stability.