Challenges of II-VI and III-V Blue Quantum Dot Light-Emitting Diodes

Quantum dot light-emitting diodes (QD-LEDs) are electroluminescent devices where the emissive layer consists of inorganic colloidal quantum dots. Recent breakthroughs have enabled the development of bright and efficient blue-emitting QD-LEDs based on heavy metal-free compositions. However, challenges remain that hinder their practical application in electroluminescent displays and lighting technologies. The primary obstacle is their limited operational lifetimes which remain significantly below practical requirement standards, especially in comparison to the red- and green-emitting QD-LEDs. Another important issue is the low color purity and broad spectral linewidths of heavy metal-free blue quantum dot compositions. Additional problems include transient electroluminescent behaviors such as fluorescence intermittency and positive aging effects. This review examines the current understanding of the physical mechanisms underlying these challenges faced by blue QD-LEDs. Often, contradictory explanations are proposed to account for the same phenomenon. Here, potential interpretations are suggested that may help reconcile the conflicting reports. Recent advances are further examined that have contributed to the development of state-of-the-art blue QD-LEDs.