Extremely low voltage and high bright p-i-n fluorescent white organic light-emitting diodes

Extremely low voltage white organic light-emitting devices (WOLEDs) with fluorescent emitters are realized exploiting p-i-n structure. White light is obtained by two complementary colors system, in which the yellow and the blue emitting components are based on 5,6,11, 12-tetraphenylnaphthacene (rubrene) and 4,4-bis-2, 2-diphenylvinyl-1, 1-spirobiphenyl (Spiro-DPVBi), respectively. The effects on the device performances of various electron blocking layers and hosts for rubrene are discussed. The best device shows a luminance of 1000 cd m2 at bias of as low as 2.9 V, and 10 000 cd m2 at 4.7 V with a maximum power efficiency of 8.7 lmW. The Commission Internationale de 1'Eclairage chromaticity coordinates change from (0.36, 0.45) at 1000 cd m2 to (0.33, 0.42) at 10 000 cd m2 showing high color stability. © 2008 American Institute of Physics.