Effect of doping different dyes in Alq3 on electroluminescence and morphology of layers using single furnace method

A method for obtaining red emission from organic-light emitting diodes has been developed by dissolving red and green dyes in a common solvent and thermally evaporating the mixture in a single furnace. Devices with fundamental structure of ITO/PEDOT: PSS (55 nm)/PVK (90 nm)/Alq3: porphyrin (50 nm)/Al (180 nm) were fabricated. The emission properties and chromaticity coordinates of the devices depend on the energy transfer between the emission of host and the absorption of the dyes. TPP and TPPNO2 doped in Alq3 showed more pure red emission compared to 3,4-TPP, and PdTPP doped in Alq3 based devices. AFM measurement showed that the morphology of the layers depends on the type of dyes and uniform mixing of porphyrin compounds and Alq3 at constant deposition rate. It is shown that this new method is a promising candidate for fabrication of low cost red OLEDs at more homogeneous layer.