Large-area perovskite LEDs (PeLEDs) are promising for cost-effective and high-throughput industrial applications. However, growing large-area efficient perovskite light emitters remains a big challenge. In a recent study in Nature Nanotechnology, Lee et al. demonstrated a simple modified bar-coating method for fabricating highly efficient and large-area perovskite nanocrystal-based PeLEDs with external quantum efficiency over 20% for a large pixel area of 900 mm(2).