Lin B.-YDing W.-CChen C.-HKuo Y.-PLee C.-YChiu T.-L.JIUN-HAW LEE2022-04-252022-04-25202120462069https://www.scopus.com/inward/record.uri?eid=2-s2.0-85108560532&doi=10.1039%2fd1ra03310g&partnerID=40&md5=067f06b0d2eb8d4db79f245a22ef848ahttps://scholars.lib.ntu.edu.tw/handle/123456789/607221Developing a colloidal quantum-dot light-emitting device (QDLED) with high efficiency and good reliability is necessarily preliminary for the next-generation high-quality display application. Most QDLED reports are focused on efficiency improvement, but the device operational lifetime issue is less addressed and also the relevant degradation mechanisms. This study achieved a 1.72 times elongation in the operational lifetime and a 9 times improvement in the efficiency of QDLED by inserting a hole-transporting/electron-blocking poly(9-vinylcarbazole) (PVK) layer, which prevented operational degradation on poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-secbutylphenyl))-diphenylamine)] (TFB) hole-transporting layer and also confined the electron in the QD-emitting layer. Although the TFB/PVK HTL structure is a well-known pair to enhance the device performance, its detailed mechanisms were rarely mentioned, especially for relative operational lifetime issues. Herein, a new insight behind operational lifetime elongation of QDLED is disclosed through various fundamental experiments including steady-state photoluminescence, transient electroluminescence and single-carrier only devices. Evidently, other than QD degradation, this study found that the other crucial factor that decreased the device lifetime was TFB-HTL degradation using steady-state photoluminescence and transient electroluminescence analyses. The PVK electron-only device exhibited a stable voltage value when it was driven by fixed current, which also affirmed that PVK has excellent electron-stability characteristics. ? The Royal Society of Chemistry 2021.DegradationDisplay devicesEfficiencyElectroluminescenceElongationLightNanocrystalsPhotoluminescenceQuantum chemistrySemiconductor quantum dotsColloidal quantum dotsEfficiency improvementFundamental experimentsHole transporting layersLight emitting devicesPoly(9-vinylcarbazole)Quantum-dot light emitting diodesTransient electroluminescenceOrganic light emitting diodes (OLED)journal article10.1039/d1ra03310g2-s2.0-85108560532