Highly efficient red OLEDs using DCJTB as the dopant and delayed fluorescent exciplex as the host.

Bo Zhao,Yuan Gao,Zisheng Su,Tianyou Zhang,Xingwu Yan,Fangming Jin,Wenlian Li,Chengyuan Liu,Bei Chu,Hairuo Wu

doi:10.1038/srep10697

Abstract

In this manuscript, we demonstrated a highly efficient DCJTB emission with delayed fluorescent exciplex TCTA:3P-T2T as the host. For the 1.0% DCJTB doped concentration, a maximum luminance, current efficiency, power efficiency and EQE of 22,767 cd m−2, 22.7 cd A−1, 21.5 lm W−1 and 10.15% were achieved, respectively. The device performance is the best compared to either red OLEDs with traditional fluorescent emitter or traditional red phosphor of Ir(piq)3 doped into CBP host. The extraction of so high efficiency can be explained as the efficient triplet excitons up-conversion of TCTA:3P-T2T and the energy transfer from exciplex host singlet state to DCJTB singlet state.

Highlights

Organic light emitting diodes (OLEDs) have being attracted tremendous attention due to their promising applications in flat-panel displays, solid state lighting and so on
Chou et al synthesized bis-4-(N-carbazolyl)phenyl)phenylphosphine oxide (BCPO)[18] with bipolar property to used as the host of Ir(piq)[3], the device provided a peak external quantum efficiency (EQE) of 17.0% and a maximum current efficiency of 19.4 cd A−1, respectively
Taking into account of the development of the delayed fluorescent exciplex, we provided a new strategy to achieve highly efficient red OLEDs by combining the delayed fluorescent exciplex with traditional fluorescent red material

Summary

OPEN Highly efficient red OLEDs using

DCJTB as the dopant and delayed received: 02 November 2014 accepted: 27 April 2015 Published: 29 May 2015 fluorescent exciplex as the host. On account of the two reasons of high efficiency with delayed fluorescent emitter and large spectral overlap, TCTA:3P-T2T exciplex was selected as the host of the fluorescent dopant DCJTB. Besides the high PLQY, the relative low concentration (1.0%) suppresses the trap of a large numbers of charges, so the energy transfer between the triplet state of exciplex and DCJTB could be prevented due to the increased intermolecular distance. Zhou and co-workers explained that the spectral blue-shift was derived from an incomplete energy transfer from exciplex to fluorescent emitter and the single emission peak was the overlap between the emission bands of exciplex and DCJTB30. Highly efficient DCJTB emission based on the energy transfer from delayed fluorescent exciplex host to fluorescent dopant was achieved. It is believed that by exploitation of more efficient delayed fluorescent exciplex, higher efficiency OLEDs could be realized

Methods

Author Contributions

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Additional Information