Color Stability Enhancement of White Organic Light-Emitting Diodes Using a Charge Control Layer
Blue phosphorescent iridium complexes iridium(III)bis[(4,6-di-fluorophenyl)-pyridinato-N,C2'] (FIrpic) and yellow phosphorescent iridium complexes Iridium(III) bis (4-phenylthieno [3,2-c]pyridinato-N,C2′)acetylacetonate (PO-01) was doped into the small molecular phosphorescent host N, N_-dicarbazolyl-3, 5-benzene (mCP) to fabricate white phosphorescent organic light-emitting diodes (white PHOLEDs). Device current efficiency is enhanced by inserting a charge control layer (CCL) into the emitting layer.
The peaks of PHOLED electroluminescent (EL) spectrum locate at 472 nm (FIrpic) and 560 nm (PO-01). A high current efficiency white PHOLED has been fabricated by the use of FIrpic and Po-01 as the double emitting layer (EML), in which the mCP is used as the CCL inserted. The doping concentration of PO-01 is optimized and the carrier transport mechanism of CCL is discussed. The optimized current efficiency is 30.06 cd/A. The CIE coordinates locate at (0.33, 0.41) and vary within (±0.01, ±0.01) under driving voltage of 5-15V.
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