Fabrication of polymer light emitting diodes with ITO/PVK:TPP/Alq3/AI structure

Polymer light emitting diodes with the configuration of ITOIPVK:TPP/Alq3/AI were fabricated using indium tin oxide (ITO) as anode, poly(9-vinylcarbazole) (PVK) as host, tetraphenylporphyrin (TPP) as red dopant, tris(8-hydroxyquinoline) aluminum (Alq3) as electron transporting green emitter and aluminum (AI) as cathode. The electrical and electroluminescence properties of the devices with various TPP doping concentrations by weight in PVK host were investigated and compared with un-doped device. The tum-on voltage of the un-doped device (von = 21 v) is larger than doped devices (von = 15 v). Besides, the el emission of the un-doped device originates only from Alq3. As for the doped devices, the light observed was the combination from TPP and Alq3 emission with different ratio. The results show that TPP dopants not only facilitates in transporting the electrons from Alq3 to TPP-doped PVK layer but also tune the emission color of the PLEDs.