PL and EL properties of oligo(p-phenylene vinylene) (OPPV) derivatives and their applications in organic light-emitting diodes (OLED)

This paper reports the photoluminescence properties and the performance enhancement of organic light-emitting diodes (OLEDs) of a series of well-defined pi-conjugated rigid rod oligomers analogous to poly(p-phenylenevinylene) (PPV). They are based on benzene-1,4-bis(phenylene vinylene) (OPPV) with electron-withdrawing (nitro) or electron-donating (methyl and dimethylamino) substituents in para-position of the terminal rings of the molecule. Substitution with methoxy and a long alkoxy group (hexadecyloxy) in 2,5-positions is also examined. Photoluminescence spectra obtained from films arc discussed and compared to those previously reported in tetrahydrofuran solutions. OPPV oligomers were then used as emissive material ill OLEDs and the I-V-L characteristics of the devices arc presented. The results show that donating groups placed on the OPPV backbone increases the performances of the devices. (C) 2008 Elsevier B.V. All rights reserved.