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 °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.

Date Published: 16 February 2017
PDF: 6 pages
Proc. SPIE 10124, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI, 1012413 (16 February 2017); doi: 10.1117/12.2252401

Published in SPIE Proceedings Vol. 10124:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI
Jong Kyu Kim; Michael R. Krames; Li-Wei Tu; Martin Strassburg, Editor(s)