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Issue 40, 2018
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Improvement of efficiency and its roll-off at high brightness in white organic light-emitting diodes by strategically managing triplet excitons in the emission layer

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Abstract

Although white organic light-emitting diodes (WOLEDs) have grown dramatically in solid-state lighting, realizing high efficiency and low efficiency roll-off simultaneously is still a prerequisite for practical applications. Here, high efficiency and low efficiency roll-off WOLEDs are presented by strategically managing triplet excitons in the emission layer. In our devices, the emission layer is constructed by strategically introducing non-doped ultrathin orange and green phosphorescent emitters in the blue phosphorescence-doped exciplex host. It can be seen that the triplet excitons within the emission layer are effectively regulated through such an engineering method. As a result, the resulting WOLED operates at a low turn-on voltage of ∼2.3 V due to well-matched energy alignment, and exhibits a maximum forward-viewing power efficiency (PE) and external quantum efficiency (EQE) of 95.3 lm W−1 and 22.8% which remain at 55.5 lm W−1 and 21.9% at 1000 cd m−2 without using light out-coupling techniques. Remarkably, at luminances of 5000 and 10 000 cd m−2, the EQEs are still as high as 20.4% and 18.9%, exhibiting extremely low efficiency roll-off. It is believed that the strategies of emission layer engineering are beneficial for the future development of high efficiency and low roll-off WOLEDs.

Graphical abstract: Improvement of efficiency and its roll-off at high brightness in white organic light-emitting diodes by strategically managing triplet excitons in the emission layer

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Publication details

The article was received on 01 Aug 2018, accepted on 18 Sep 2018 and first published on 19 Sep 2018


Article type: Paper
DOI: 10.1039/C8TC03823F
J. Mater. Chem. C, 2018,6, 10793-10803

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    Improvement of efficiency and its roll-off at high brightness in white organic light-emitting diodes by strategically managing triplet excitons in the emission layer

    S. Ying, D. Yang, X. Qiao, Y. Dai, Q. Sun, J. Chen, T. Ahamad, S. M. Alshehri and D. Ma, J. Mater. Chem. C, 2018, 6, 10793
    DOI: 10.1039/C8TC03823F

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