Ultrabright and Stable Top-Emitting Quantum-Dot Light-Emitting Diodes with Negligible Angular Color Shift.

Top emission can enhance luminance, color purity, and panel-manufacturing compatibility for emissive displays. Still, top-emitting quantum-dot light-emitting diodes (QLEDs) suffer from poor stability, low light outcoupling, and non-negligible viewing-angle dependence because, for QLEDs with non-red emission, the electrically optimum device structure is incompatible with single-mode optical microcavity. Here, we demonstrate that by improving the way of determining reflection penetration depths and creating refractive-index-lowering processes, the issues faced by green QLEDs can be overcome. This leads to advanced device performance, including a luminance exceeding 1.6 million nits, a current efficiency of 204.2 cd A-1, and a T 95 operational lifetime of 15,600 hours at 1000 nits. Meanwhile, our design does not compromise light outcoupling as it offers an external quantum efficiency of 29.2% without implementing light extraction methods. Lastly, an angular color shift of Delta u'v' = 0.0052 from 0 degrees to 60 degrees is achieved by narrowing the emission linewidth of quantum dots. By improving the method of determining the penetration depth, lowering film refractive indices, and narrowing emission linewidth, Li et al. report single mode top-emitting green QLEDs with EQE of 29.2%, luminance of 1.6 million nits, T95 of 15,600 h at 1000 nits, and negligible angular colour shift.