Synthesis of Poly(p-phenylene-vinylene) Derivatives Containing an Oxadiazole Pendant Group and Their Applications to Organic Electronic Devices

Abstract

Poly(p-phenylene vinylene) (PPV) derivatives with 2,5-diphenyl-1,3,4-oxadiazole-diyl (OXD) as the side chain, poly[2-{4[5-(4-(heptyloxy)phenyl)-1,3,4-oxadiazole-2-yl]phenyl-oxy}-1,4-phenylenevinylene] (OXH-PPV), poly[2-{4[5-(4-(heptyloxy)phenyl)-1,3,4-oxadia-zole-2-yl]phenyl-oxy}-1,4-phenylenevinylene-co-2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (OXH-PPV-co-MEH-PPV), and poly[2-methoxy-5-(2'-ethylhexyl-oxy)-p-phenylene vinylene] (MEH-PPV), were synthesized via a modified Gilch route. The electron-deficient oxadiazole moiety was introduced on the side chain of the polymer backbone to increase the electron-affinity of the polymers. The electroluminescent (EL) properties of the resulting polymers as an active layer, were investigated by the fabrication of single-layer LEDs and the devices using OXH-PPV-co-MEH-PPV showed better EL properties than those using Pure MEH-PPV. Also, to investigate the switching properties of the resulting polymers as an active layer, OFET devices were fabricated in a top-contact/bottom-gate configuration. The resulting FETs exhibited typical p-channel characteristics, field-effect mobility of 6.5 x 10(-4)-7.0 x 10(-5) cm(2) V-1 s(-1), and on-off ratio of about 10(4)-10(5).