Improved efficiency in red phosphorescent organic light-emitting devices using double doping structure

Light emission efficiency of red phosphorescent organic light-emitting diodes was improved by using a double doping structure in light emitting layer. Red devices with tris(2-phenylpyridine) iridium (Ir(ppy)3) as a co-dopant for tris(1-phenylisoquinoline) iridium (Ir(piq)3) showed higher efficiency than Ir(piq)3 device. Ir(ppy)3 acted as a sensitizer for energy transfer from (4,4′-N,N′-dicarbazole)biphenyl to Ir(piq)3 and enhanced luminance efficiency of Ir(piq)3 by 30%.