title: Simultaneous optimization of charge-carrier mobility and optical gain in semiconducting polymer films.
abstract: The combination of efficient light emission and high charge-carrier mobility has thus far proved elusive for polymer semiconductors, with high mobility typically achieved by cofacial pi-electron system to pi-electron system interactions that quench exciton luminescence. We report a new strategy, comprising the introduction of a limited number of more effective hopping sites between otherwise relatively isolated, and thus highly luminescent, polyfluorene chains. Our approach results in polymer films with large mobility (mu approximately 3-6 x 10(-2) cm2 V-1 s-1) and simultaneously excellent light-emission characteristics. These materials are expected to be of interest for light-emitting transistors, light-emitting diode sources for optical communications and may offer renewed hope for electrically pumped laser action. In the last context, optically pumped distributed feedback lasers comprising one-dimensional etched silica grating structures coated with polymer have state-of-the-art excitation thresholds (as low as 30 W cm(-2) (0.1 nJ per pulse or 0.3 microJ cm-2) for 10 Hz, 12 ns, 390 nm excitation) and slope efficiencies (up to 11%).
authors.affiliation: The Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
authors.forename: Boon Kar
authors.initials: BK
authors.lastname: Yap
authors.forename: Ruidong
authors.initials: R
authors.lastname: Xia
authors.forename: Mariano
authors.initials: M
authors.lastname: Campoy-Quiles
authors.forename: Paul N
authors.initials: PN
authors.lastname: Stavrinou
authors.forename: Donal D C
authors.initials: DD
authors.lastname: Bradley