Improvement of thermal stability of type-II composition-gradient thick-shell quantum dots green light-emitting diodes

Improvement of thermal stability of green quantum dot light emitting diodes (QD-LEDs) was demonstrated by using composition-gradient thick-shell CdSe@ ZnS/ZnS quantum dots (QDs). The electroluminescence intensity only decreased 3% even when the operation temperature was elevated to 110 degrees C. The current efficiency roll-off effect was improved nearly 200% under higher current density. Thick-shell QDs with low defective structure could effectively prevent the electron-hole pairs from nonradiative Auger recombination and avoid the thermal-stress-induced expansion at higher temperatures and driving current. The maximum current efficiency of the thick-shell-device is 10.3 cd/A, which is much higher than 1.57 cd/A for the conventional thin-shell-device.