title: Silsesquioxane-based nanocomposite dendrimers with photo-luminescent and charge transport properties.
abstract: The synthesis and characterization of octavinylsilsesquioxane (OVS)-based nanocomposite dendrimers with luminescent and charge transport properties are reported. The nanocomposite dendrimers were prepared in high yield using mild Heck chemistry of mono-haloaromatic compounds with the peripheral vinylsilane groups of OVS. Attachment of 2-naphthalene, 2-(9,9-dimethyl)fluorene, and 2-(4-phenyl)-5-(1-naphthyl)-1,3,4-oxadiazole resulted in materials with blue-violet emission (360-380 nm) and photo-luminescent quantum efficiencies (PLQEs) from 1 to 26%. Blue-green emission was observed for attachment of 1-pyrene, 9-anthracene, and N1-(4-phenyl)-N1,N4,N4-triphenylbenzene-1,4-diamine with PLQEs ranging from 23 to 50%. Despite the planar characteristics of the organic dendrons, the nanocomposite dendrimers are completely amorphous and have high glass transition temperatures (Tg) ranging from 115 to 186 degrees C with decomposition temperatures (Td) exceeding 450 degrees C. Matrix-assisted laser desorption ionization-time of flight shows that unlike traditional Heck chemistry, haloaromatic compounds are adding twice across the vinylsilane groups. Finally, organic light emitting diodes using the aromatic amine-based dendrimer as hole injection layers show 55% improvement in device efficiency over traditional materials (5.16 vs. 3.24 cd A(-1)) with brightness levels exceeding 40,000 cd m(-2).
authors.affiliation: Institute of Materials Research and Engineering (IMRE), 3 Research Link, 117602, Singapore.
authors.forename: Mee Yoon
authors.initials: MY
authors.lastname: Lo
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ueno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanabe
authors.forename: Alan
authors.initials: A
authors.lastname: Sellinger
mesh_terms: D050091:Dendrimers / Q000138:chemical synthesis / Q000737:chemistry*; D004553:Electric Conductivity; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D010777:Photochemistry; D012680:Sensitivity and Specificity; D012828:Silicones / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D050091:Dendrimers; D012828:Silicones