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/m(2) at bias of as low as 2.9 V, and 10 000 cd/m(2) at 4.7 V with a maximum power efficiency of 8.7 lm/W. The Commission Internationale de l'Eclairage chromaticity coordinates change from (0.36, 0.45) at 1000 cd/m(2) to (0.33, 0.42) at 10 000 cd/m(2) showing high color stability. (C) 2008 American Institute of Physics.