title: Cyclodextrin-threaded conjugated polyrotaxanes as insulated molecular wires with reduced interstrand interactions.
abstract: Control of intermolecular interactions is crucial to the exploitation of molecular semiconductors for both organic electronics and the viable manipulation and incorporation of single molecules into nano-engineered devices. Here we explore the properties of a class of materials that are engineered at a supramolecular level by threading a conjugated macromolecule, such as poly(para-phenylene), poly(4,4'-diphenylene vinylene) or polyfluorene through alpha- or beta-cyclodextrin rings, so as to reduce intermolecular interactions and solid-state packing effects that red-shift and partially quench the luminescence. Our approach preserves the fundamental semiconducting properties of the conjugated wires, and is effective at both increasing the photoluminescence efficiency and blue-shifting the emission of the conjugated cores, in the solid state, while still allowing charge-transport. We used the polymers to prepare single-layer light-emitting diodes with Ca and Al cathodes, and observed blue and green emission. The reduced tendency for polymer chains to aggregate allows solution-processing of individual polyrotaxane wires onto substrates, as revealed by scanning force microscopy.
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK. f.cacialli@ucl.ac.uk
authors.forename: Franco
authors.initials: F
authors.lastname: Cacialli
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Wilson
authors.forename: Jasper J
authors.initials: JJ
authors.lastname: Michels
authors.forename: Clement
authors.initials: C
authors.lastname: Daniel
authors.forename: Carlos
authors.initials: C
authors.lastname: Silva
authors.forename: Richard H
authors.initials: RH
authors.lastname: Friend
authors.forename: Nikolai
authors.initials: N
authors.lastname: Severin
authors.forename: Paolo
authors.initials: P
authors.lastname: Samorì
authors.forename: Jürgen P
authors.initials: JP
authors.lastname: Rabe
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Connell
authors.forename: Peter N
authors.initials: PN
authors.lastname: Taylor
authors.forename: Harry L
authors.initials: HL
authors.lastname: Anderson
mesh_terms: D003505:Cyclodextrins / Q000737:chemistry*; D004553:Electric Conductivity; D008027:Light; D008163:Luminescent Measurements; D046911:Macromolecular Substances; D008422:Materials Testing / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000295:instrumentation*; D010777:Photochemistry / Q000379:methods; D011108:Polymers / Q000737:chemistry; D011786:Quality Control; D043862:Rotaxanes; D012666:Semiconductors; D012680:Sensitivity and Specificity
chemical_list: D003505:Cyclodextrins; D046911:Macromolecular Substances; D011108:Polymers; D043862:Rotaxanes