Organic Soluble Deoxyribonucleic Acid (DNA) Bearing Carbazole Moieties and Its Blend with Phosphorescent Ir(III) Complexes

Abstract

A functionalized deoxyribonucleic acid (Cz-DNA) was prepared with carbazolyl ammonium lipid as a triplet host material for phosphorescent material system. It is soluble in organic solvents, which facilitates the sample preparation for the absorption and luminescent properties in solid states. A highly soluble iridium complex, Ir(Cz-ppy)(3) with carbazolyl-substituted 2-phenylpyridine ligands was employed for studying the phosphorescence in Cz-DNA. There is a good overlap between the photoluminescence spectrum of Cz-DNA and the metal-to-ligand charge transfer (MLCT) absorption bands of the iridium complex. This overlap enables efficient energy transfer from the excited state in the host to the MLCT band of Ir(Cz-ppy)(3). In addition, photoluminescence quantum yield of Cz-DNA was found to be relatively larger than the copolymer (PCzSt) with vinylcarbazole and styrene. Thus, Cz-DNA was employed as a triplet host material for fabricating multilayered electrophosphorescence devices via modification of its property by doping 5,4-tert-butylhexyl-1,3,4-oxadiazole (PBD). After doping 30 wt % PBD and 10 wt Ir(Cz-ppy)(3) into Cz-DNA, we achieved much improvement in electron injection/transport from an adjacent carrier transport layer, resulting in much improved device performances. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1913-1918, 2010