Abstract
We demonstrate high-efficient white organic light-emitting diodes (WOLEDs) based on triplet multiple quantum well (MQW) structure and focus on the influence on WOLEDs through employing different potential barrier materials to form type-I and type-II MQWs, respectively. It is found that type-I MQW structure WOLEDs based on 1,3,5-tris(N-phenyl-benzimidazol-2-yl)benzene as potential barrier layer (PBL) offers high electroluminescent (EL) performance. That is to say, maximum current efficiency and power efficiency are achieved at about 1,000 cd/m2 with 16.4 cd/A and 8.3 lm/W, which increase by 53.3% and 50.9% over traditional three-layer structure WOLEDs, respectively, and a maximum luminance of 17,700 cd/m2 is earned simultaneously. The achievement of high EL performance would be attributed to uniform distribution and better confinement of carriers within the emitting layer (EML). However, when 4,7-diphenyl-1,10-phenanthroline or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline is used as PBL to form type-II MQW structure, poor EL performance is obtained. We attribute that to improper energy level alignment between the interface of EML/PBL, which leads to incomplete confinement and low recombination efficiency of carriers, a more detailed mechanism was argued.
Highlights
Compared to inorganic light-emitting diodes (LEDs), which have developed for several decades and are still being researched [1,2,3], organic light-emitting diodes (OLEDs) have attracted intensive attention due to their bright future on practical application [4,5]
white organic light-emitting diodes (WOLEDs) with TPBi as potential barrier layer (PBL) exhibits a peak current efficiency and a power efficiency of 16.4 cd/A and 8.3 lm/W at about 1,000 cd/m2, which increase by 53.3% and 50.9% over the reference device, respectively; a maximum luminance of 17,700 cd/m2 is achieved, which keeps a similar luminance with the reference device
The achievement of high EL performance with type-I multiple quantum well (MQW) structure WOLEDs would be attributed to the uniform distribution and rigorous confinement of carriers and excitons within emitting layer (EML)
Summary
Compared to inorganic light-emitting diodes (LEDs), which have developed for several decades and are still being researched [1,2,3], organic light-emitting diodes (OLEDs) have attracted intensive attention due to their bright future on practical application [4,5]. WOLEDs with the MQW structure have been reported, thanks to the confinement of carriers and excitons within potential wells, but their emissive efficiency is generally lower than that of the traditional three-layer structure. The reason for the low efficiency of those MQW structure WOLEDs are attributed to the use of fluorescent material only and incomplete confinement of charge carriers and excitons within the emitting layer (EML) due to adoption of undeserved potential barrier layer (PBL) materials. Our group had designed triplet MQW structure WOLEDs in which 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) was used as PBL, and blue fluorescent dye and orange phosphor doped EML were used as two potential well layers (PWLs), respectively [12]. During the process of researching the triplet MQW structure, it is found that the PBL material played a key role in improving the performance of WOLEDs, and the distribution of carriers with different PBL materials was different, but it seemed that such issues have rarely been taken into account
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
