title: Band-Edge Exciton Fine Structure and Recombination Dynamics in InP/ZnS Colloidal Nanocrystals.
abstract: We report on a temperature-, time-, and spectrally resolved study of the photoluminescence of type-I InP/ZnS colloidal nanocrystals with varying core size. By studying the exciton recombination dynamics we assess the exciton fine structure in these systems. In addition to the typical bright-dark doublet, the photoluminescence stems from an upper bright state in spite of its large energy splitting (∼100 meV). This striking observation results from dramatically lengthened thermalization processes among the fine structure levels and points to optical-phonon bottleneck effects in InP/ZnS nanocrystals. Furthermore, our data show that the radiative recombination of the dark exciton scales linearly with the bright-dark energy splitting for CdSe and InP nanocrystals. This finding strongly suggests a universal dangling bonds-assisted recombination of the dark exciton in colloidal nanostructures.
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany.
authors.forename: Louis
authors.initials: L
authors.lastname: Biadala
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Siebers
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany.
authors.forename: Yasin
authors.initials: Y
authors.lastname: Beyazit
authors.forename: Mickaël D
authors.initials: MD
authors.lastname: Tessier
authors.forename: Dorian
authors.initials: D
authors.lastname: Dupont
authors.forename: Zeger
authors.initials: Z
authors.lastname: Hens
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany.|Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia.
authors.forename: Dmitri R
authors.initials: DR
authors.lastname: Yakovlev
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany.|Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia.
authors.forename: Manfred
authors.initials: M
authors.lastname: Bayer
keywords: Cd-free; dangling bonds; dark exciton; fine structure; phonon bottleneck