Reducing roll-off effect of efficient green quantum-dot light-emitting diodes via composition-gradient thick-shell quantum dots

Abstract

In this study, we investigated the stable and efficient quantum-dot light emitting diodes (QLEDs) under high driving current by using composition-gradient thick-shell CdSe@ZnS/ZnS QDs. Thick-shell QDs with low defective structure can effectively avoid the electron-hole pairs from nonradiative Auger recombination and prevent thermal-stress-induced expansion at high driving current. Consequently, roll-off effect in electroluminescent feature can be reduced almost two times. Moreover, the maximum current efficiency of thick-shell-device is 10.3 cd/A, which much higher than 1.57 cd/A in thin-shell-device.