The mechanism of energy transfer leading to electroluminescence (EL) of a lanthanide complex, Eu x Y (1-x) (TTA) 3 Phen (TTA= thenoyltrifluoro-acetone, phen=1,10-phenanthroline), doped into TPBi(1,3,5-tris(N-Phenyl-benzimidizol-2-yl) benzene host at 15 wt% of host is investigated. With the device structure of anode/hole transport layer/Eu x Y (1-x) (TTA) 3 Phen (15%): TPBi/electron transport layer/cathode, maximum luminescence of 185.6 cd/m 2 and 44.72 cd/m 2 was obtained from device I made of Eu 0.4 Y 0.6 (TTA) 3 Phen and device II made of Eu 0.5 Y 0.5 (TTA) 3 Phen, respectively at 18 volts. Saturated red Eu 3+ emission based on 5 D 0 → 7 F 2 transition is centered at a wavelength of 612 nm with a full width at half maximum of 5 nm. From the analysis of I-V, J-V-L characteristics and electroluminescent (EL) spectra, we conclude that direct trapping of holes and electrons and subsequent formation of the excitation occur on the dopant, leading to high quantum efficiencies at low current densities. These results show that fabricated OLED devices can successfully emit saturated red light and can be used in applications such as opto-electronic OLED devices, displays and solid state lighting technology.

No abstract

No abstract

No abstract

Using a blue emitting material, 4-bis(2,2-diphenylvinyl)-1,1-biphenyl and orange dopant 5,6,11,12-tetraphenyl-naphthacene, white organic light-emitting devices have been fabricated. An insignificant variation in Commission Internationale de l’Eclairage color index with the applied voltage is reported. Transient electroluminescence measurements show a delay time in the microsecond range (<26μs). The authors propose a device configuration for the white light emission, having a color stability and low delay time.