Study of sequential dexter energy transfer in high efficient phosphorescent white organic light-emitting diodes with single emissive layer

Jin Wook Kim; Seung Il You; Nam Ho Kim; Ju-An Yoon; Kok Wai Cheah; Fu Rong Zhu; Woo Young Kim

doi:10.1038/srep07009

Study of sequential dexter energy transfer in high efficient phosphorescent white organic light-emitting diodes with single emissive layer

Sci Rep. 2014 Nov 12:4:7009. doi: 10.1038/srep07009.

Authors

Jin Wook Kim¹, Seung Il You¹, Nam Ho Kim¹, Ju-An Yoon¹, Kok Wai Cheah², Fu Rong Zhu², Woo Young Kim³

Affiliations

¹ Department of Green Energy &Semiconductor Engineering, Hoseo University, Asan, Korea.
² Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong, China.
³ 1] Department of Green Energy &Semiconductor Engineering, Hoseo University, Asan, Korea [2] Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7, Canada.

Abstract

In this study, we report our effort to realize high performance single emissive layer three color white phosphorescent organic light emitting diodes (PHOLEDs) through sequential Dexter energy transfer of blue, green and red dopants. The PHOLEDs had a structure of; ITO(1500 Å)/NPB(700 Å)/mCP:Firpic-x%:Ir(ppy)3-0.5%:Ir(piq)3-y%(300 Å)/TPBi(300 Å)/Liq(20 Å)/Al(1200 Å). The dopant concentrations of FIrpic, Ir(ppy)3 and Ir(piq)3 were adjusted and optimized to facilitate the preferred energy transfer processes attaining both the best luminous efficiency and CIE color coordinates. The presence of a deep trapping center for charge carriers in the emissive layer was confirmed by the observed red shift in electroluminescent spectra. White PHOLEDs, with phosphorescent dopant concentrations of FIrpic-8.0%:Ir(ppy)3-0.5%:Ir(piq)3-0.5% in the mCP host of the single emissive layer, had a maximum luminescence of 37,810 cd/m(2) at 11 V and a luminous efficiency of 48.10 cd/A at 5 V with CIE color coordinates of (0.35, 0.41).