Molecular Doped Polymer Light Emiting Diodes with Air－stable Aluminum as Cathode

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Molecular Doped Polymer Light Emitting Diodes with Air-stable Aluminum as Cathode

By using air-stable aluminum as cathode,molecular doped polymer (MDP) blue light emitting diodes (LEDs)were constructed.Poly(N-vinylcarbazole)(PVK) doped with,1,1,4,4-tetrapheny 1-1,3-butadiene(TPB) was used as the light-emitting layer,a layer of 2-(4-biphenylyl)-5-(4-terbutypheny)1-3,4-oxadiazole(PBD) as hole-blocking,electron-transporting layer and a layer of tris(8-quinolinolate)-Aluminum(Alq 3)film also worked as an electron-transporting layer.The device with structure of ITO/PVK:TPB/PBD/Alq 3/Al was fabricated.Blue emission began at about 4 V,more than 1 000 cd/m 2 was achieved at 14 V.This is the lowest turn-on voltage for polymeric light-emitting diodes(PLEDs) used air-stable electrodes.Such low-operating voltage,especially using air-stable aluminum as cathode,may be helpful for the devices to be used in commercially viable displays.