title: Efficient upconversion fluorescence in a blue-emitting spirobifluorene-anthracene copolymer doped with low concentrations of Pt(II)octaethylporphyrin.
abstract: Upconversion-induced fluorescence in platinum-octaethylporphyrin (PtOEP)-doped thin films of a spirobifluorene-anthracene copolymer has been investigated. Upon exciting in the range of the absorption band (2.31 eV, 537 nm) of the guest molecules, blue fluorescence (2.75 eV, 450 nm) from the spirobifluorene host was observed. The intensity of the upconverted emission was found to be one order of magnitude higher than from a PtOEP doped but anthracene-free spirobifluorene copolymer and than previously reported for metallated porphyrin-doped polyfluorene samples. It is argued that the efficient upconversion originates from the triplet energy transfer from the phosphorescent dopant to the sensitive unit of the host polymer, followed by triplet-triplet annihilation and finally blue emission from the spirobifluorene host polymer backbone.
authors.affiliation: Max Planck Institute for Polymer Research Mainz, Ackermannweg 10, D-55128 Mainz, Germany. laquai@mpip-mainz.mpg.de
authors.forename: Frédéric
authors.initials: F
authors.lastname: Laquai
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wegner
authors.forename: Chan
authors.initials: C
authors.lastname: Im
authors.forename: Arne
authors.initials: A
authors.lastname: Büsing
authors.forename: Susanne
authors.initials: S
authors.lastname: Heun