Recent progress and challenges in top‐emitting quantum dot light‐emitting diodes

Abstract

Top‐emitting quantum‐dot light‐emitting diodes (TE‐QLEDs) have been recognized as a key architecture for next‐generation displays, as they overcome substrate‐mode losses in bottom‐emitting devices, enable high aperture ratios, and are compatible with complementary metal–oxide–semiconductor backplanes. The reflective bottom electrode and semi‐transparent top electrode in TE‐QLEDs inherently form an optical microcavity, which can enhance resonant emission, improve color purity, and increase directionality. However, strong microcavity effects also induce angular‐dependent emission, viewing‐angle color shifts, and sensitivity to structural variations. In parallel, device lifetime remains limited by top‐electrode–induced damage, microcavity–transport coupling–related charge imbalance, and heat accumulation under high‐brightness operation. This review summarizes recent progress in TE‐QLEDs, covering device architectures and applications, microcavity effects, angular emission behavior, and operational stability. Strategies for improving light extraction, suppressing angular color shifts, and extending device lifetime through optical–electrical–thermal co‐optimization are systematically discussed. Finally, remaining challenges and future research directions toward achieving reliable, high‐performance TE‐QLEDs are outlined.