Cyclodextrin-threaded conjugated polyrotaxanes as insulated molecular wires with reduced interstrand interactions.
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.
Cacialli
Franco
F
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK. f.cacialli@ucl.ac.uk
Wilson
Joanne S
JS
Michels
Jasper J
JJ
Daniel
Clement
C
Silva
Carlos
C
Friend
Richard H
RH
Severin
Nikolai
N
Samorì
Paolo
P
Rabe
Jürgen P
JP
O'Connell
Michael J
MJ
Taylor
Peter N
PN
Anderson
Harry L
HL
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
D003505:Cyclodextrins; D046911:Macromolecular Substances; D011108:Polymers; D043862:Rotaxanes