Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5399456 | Journal of Luminescence | 2014 | 28 Pages |
Abstract
To obtain white electroluminescence (EL) with a high color rendering index (CRI), we fabricated polymer light-emitting diodes (PLEDs) co-doped with high-efficiency blue-, yellow- and red-phosphorescent bis-cyclometalated iridium(III) complexes (Ir-1, Ir-2, and Ir-3, respectively) in a single emitting layer based on a PVCz-OXD-7 blended film (PVCz, poly(9-vinylcarbazole); OXD-7, 1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene). When the constituent ratio of the emitting layer (PVCz:OXD-7:Ir-1:Ir-2:Ir-3) was adjusted to 10:3.0:1.2:0.060:0.036 in weight ratio, an approximately white PLED (WPLED) was obtained showing a Commission Internationale de l׳Eclairage (CIE) chromaticity coordinate of (0.38, 0.44) and a CRI of 83 at 1000 cd mâ2. To elucidate the energy transfer among the phosphorescent emitters, we also investigated the photophysical properties of the PVCz-based thin film whose constituent ratio is the same as the emitting layer of the WPLED, and it was found that a cascade of the energy transfer from the blue to the red via the yellow emitter considerably contributes to the emission process along with the direct energy transfer from the blue to the red and yellow emitters.
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Shigeru Ikawa, Shigeyuki Yagi, Takeshi Maeda, Hiroyuki Nakazumi, Yoshiaki Sakurai,