Electroluminescence of a Multi-Layered Organic Light-Emitting Diode Utilizing Trans-4-p-N-methyl-N-(hydroxymethyl)aminostyryl-N-Methylphridinium Tetraphenylborate as the Active Layer

Employing an organic dye salt of trans-4-p-N-methyl-N-(hydroxymethyl)aminostyryl-N-methylphridinium tetra\-phenylborate (ASPT) as the active layer, 8-hydrocyquinoline aluminium (Alq₃) as the electron transporting layer and N,N’-diphenyl-N,N’-bis(3-methylphenyl)-1,1’-biphenyl-4,4’-diamine (TPD) as the hole transporting layer, respectively, we fabricate a multi-layered organic light-emitting diode and observe the colour tunable electroluminescence (EL). The dependence of the EL spectra on the applied voltage is investigated in detail, and the recombination mechanism is discussed by considering the variation of the hole-electron recombination region.