Low pressure organic vapor phase deposition of small molecular weight organic device structures

A new technique for the deposition of amorphous organic thin films, low pressure organic vapor phase deposition (LP-OVPD), was used to fabricate organic light emitting devices (OLEDs) and optically pumped organic lasers. The OLED consisted of a film of aluminum tris(8 hydroxyquinoline) (Alq(3)) grown on the surface of a film of N'-diphenyl-N,N'-bis(3-methylphenyl)1-1'biphenyl-4-4'diamine (TPD). Growth on both glass and polyester substrates was accomplished and the resulting heterojunction devices were found to have a performance similar to conventional, small molecular weight OLEDs grown using thermal evaporation in vacuum. The LP-OVPD grown OLED has an external quantum efficiency of 0.40 +/- 0.05% and a turn-on voltage of approximately 6V. The optically pumped organic laser consisted of a film of Alq(3) doped with the laser dye, benzoic acid, 2-[6-(ethylamino)-3-(ethylimino)-2,7-dimethyl-3H-xanthen-9-yl]-ethyl ester, monohydrochloride (Rhodamine 6G). The laser output was centered at approximately 610nm and the lasing threshold was 30 mu Jcm(-2). The rapid throughput of LP-OVPD and its use of low vacuum in a horizontal reactor demonstrate its potential to facilitate low cost, roll-to-roll deposition of organic films for many photonic device applications.