Effect of triplet multiple quantum well structures on the performance of blue phosphorescent organic light-emitting diodes.
We investigate multiple quantum well [MQW] structures with charge control layers [CCLs] to produce highly efficient blue phosphorescent organic light-emitting diodes [PHOLEDs]. Four types of devices from one to four quantum wells are fabricated following the number of CCLs which are mixed p- and n-type materials, maintaining the thickness of the emitting layer [EML]. Remarkably, such PHOLED with an optimized triplet MQW structure achieves maximum luminous and external quantum efficiency values of 19.95 cd/A and 10.05%, respectively. We attribute this improvement to the efficient triplet exciton confinement effect and the suppression of triplet-triplet annihilation which occurs within each EML. It also shows a reduction in the turn-on voltage from 3.5 V (reference device) to 2.5 V by the bipolar property of the CCLs.
Department of Information Display, Hongik University, Seoul, 121-791, South Korea. ssyoon@skku.edu.
Seokjae
S
Lee
Jaryong
J
Koo
Gunwoo
G
Hyung
Donghwan
D
Lim
Donghyung
D
Lee
Kumhee
K
Lee
Seungsoo
S
Yoon
Wooyoung
W
Kim
Youngkwan
Y
Kim