High-Efficiency, Large-Area, Flexible Top-Emitting Quantum-Dot Light-Emitting Diode

Flexible displays are essential to provide information in real time for human–machine interactions. As a next-generation display technology, quantum-dot light-emitting diodes (QLEDs) are potentially serving as key components for flexible displays. However, it is still challenging for QLEDs to simultaneously achieve flexibility, large-scale production, and high efficiencies. To this end, a strategy is proposed here by combining a top-emitting structure, optical microcavity optimization, and large-scale film preparation. A top-emitting microcavity with semitransparent and reflective metals is designed to achieve flexibility, efficient carrier injection, and high light extraction efficiency. Precision manufacturing of large-area QLEDs with the designed top-emitting microcavity is achieved by combining surfactant-assisted blade-coating and vacuum thermal evaporation processes. With this strategy, a large-area flexible QLED with an active area of 400 mm2 and a maximum external quantum efficiency of 21.8% is developed. This strategy provides a promising approach toward the development of flexible displays with the demonstration of a 1.3 in. passive-matrix flexible QLED display of 19 by 19 pixels.