ANALYSIS ON OPERATIONAL STABILITY FOR STABLE QUANTUM DOT LIGHT-EMITTING DIODES

Colloidal quantum dot light-emitting diodes (QLEDs) are p-i-n junction diodes exhibiting excellence in color gamut, brightness and flexible form factors, promising their use in next-generation displays.Within the last few decades, QLEDs have demonstrated great progress in efficiency and brightness that are comparable to the performance of commercialized organic light-emitting diodes (OLEDs) are reported.To enhance performance of QLEDs, lots of attempts have been made on QD and QLED, such as modifying core/shell composition and structure, surface ligand modification, and optimization QLEDs device architectures.Through these methods, increase in operational lifetime at 1000 nit.(75% lifetime (LT75) ~ 5.6 hours @ 1000 cd/m 2 for non-C60 interlayer QLEDs and (LT75) ~ 36.5 hours @ 1000 cd/m 2 for C60 interlayer QLEDs).Comprehensive study across spectroscopic analysis on the QD emissive layer and optoelectronic characterization on working devices under all-else-being-equal operation conditions enable us to understand the key factors that are responsible for the device degradation.The device efficiency drop at Stage I is attributed solely to the charge injection imbalance into QDs.The device efficiency loss at Stage II is also attributed mainly to the charge injection imbalance, and further exacerbated by the increase in the operation voltage.These results shows the impact of charge injection balance on the device performance, and suggest that the equalized charge injection will enable complete eradication of device degradation factors and promise prolonged operation lifetime of QLEDs.I believe that engineering at the interface between QDs and HTL will certainly enable the complete charge injection balance and a long-lived QLED.