Ternary system of single-layer organic-light-emitting diodes (OLEDs) were fabricated containing tris(8-hydroxyquinoline) aluminium (Alq 3) blended with N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl-4,4-diamine and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole small molecules. Electroluminescence properties were investigated with respect to blend systems. Significant improvement in turn-on voltage and luminance intensity was observed by employing the blends technique. Negative differential resistance (NDR) characteristics observed at a low voltage region in blended OLED is related to the generation of guest hopping site and phonon scattering phenomenon. However, luminescence of the devices is not altered by the NDR effect.
ZnO thin films with and without Ni-doping were successfully deposited by sol-gel method with zinc acetate dihydrate as inorganic precursor, and nickel (II) acetate tetrahydrate as dopant. The solutions were prepared by dissolving zinc acetate and nickel (II) acetate in ethanol and diethanolamine (DEA) as its chelating agent. Thin films were fabricated by using spin-coating method on glass substrates. ZnO films were obtained by pre-heating and post-heating at 300 °C for 10 minutes and 500 °C for 1 h respectively. The films were analyzed by X-ray diffraction (XRD), UV-Vis transmittance and photoluminescence (PL). All samples exhibit high transparency in visible. Ni dopant does not alter so much ZnO structure, which due to the ion substitution between Ni and Zn. However, the Ni tends to create a dopant energy interlayer in ZnO energy band gap which cause significant change in PL intensity.
This research work investigates the influence of the annealing process upon the performance of photo-emissive layer of organic light-emitting diode (OLED). The photo-emissive layer consists of a ternary blend of N, N-diphenyl-N,N-bis (3-methylphenyl)-(1,1-biphenyl)-4,4-diamine (TPD), 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) and tris-8-hydroxyquinoline (Alq3), to produce TPD:PBD:Alq3 (at 1:1:1 ratio) blend thin films, in which the material solutions are deposited onto clean substrate via spin-coating method. The samples were annealed at 100°C in 10, 20 and 30 minute of time in an open-air condition. The results reveal that the annealing process at 10 minutes produces an optimum performance of the ternary OLED.
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