title: Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots.
abstract: Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling.
authors.affiliation: School of Physics and Astronomy & Photon Science Institute, University of Manchester, Manchester, M13 9PL, UK.
authors.forename: Musa
authors.initials: M
authors.lastname: Cadirci
authors.forename: Stuart K
authors.initials: SK
authors.lastname: Stubbs
authors.forename: Samantha J O
authors.initials: SJ
authors.lastname: Hardman
authors.forename: Ombretta
authors.initials: O
authors.lastname: Masala
authors.forename: Guy
authors.initials: G
authors.lastname: Allan
authors.forename: Christophe
authors.initials: C
authors.lastname: Delerue
authors.forename: Nigel
authors.initials: N
authors.lastname: Pickett
authors.forename: David J
authors.initials: DJ
authors.lastname: Binks