Quenching-enhanced shift of recombination zone in phosphorescent organic light-emitting diodes

✍ Scribed by G.Y. Zhong; Y.Q. Zhang; X.A. Cao

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 941 KB
• Volume: 11
• Category: Article
• ISSN: 1566-1199
• DOI: 10.1016/j.orgel.2010.05.010

✦ Synopsis

We studied the influence of concentration quenching on exciton distribution and recombination in organic light-emitting diodes (OLEDs) with a neat fac-tris(2-phenylpyridinato-N, C2 0 ) iridium (III) [Ir(ppy) 3 ] emitting layer (EML). It has been found that electron overflow to the hole transport layer (HTL) at elevated currents was enhanced by quenching in the EML, leading to a broadened recombination zone. The maximum quenching of green phosphorescence occurred in OLEDs with 4 nm Ir(ppy) 3 and correlated well with the strongest blue fluorescence from the HTL. The OLEDs emitted white light with an efficiency of 6.5 cd/A and a quantum efficiency twice as high as compared to similar OLEDs with an additional 4,4 0 ,4 00 ,-tris(N-carbazolyl) triphenylamine (TCTA) EBL.