title: Steady-state photoinduced absorption of CdSe/CdS octapod shaped nanocrystals.
abstract: Colloidal branched nanocrystals have been attracting increasing attention due to evidence of an interesting relationship between their complex shape and charge carrier dynamics. Herein, continuous wave photoinduced absorption (CW PIA) measurements of CdSe/CdS octapod-shaped nanocrystals are reported. CW PIA spectra show strong bleaching due to the one-dimensional (1D) CdS pod states (480 nm) and the zero-dimensional (0D) CdSe core states (690 nm). The agreement with previously reported ultrafast pump-probe experiments indicates that this strong bleaching signal may be assigned to state filling. Additional bleaching features at 520 and 560 nm are characterized by a longer lifetime and are thus ascribed to defect states, localized at the pod-core interface of the octapod, showing that some of the initially photogenerated carriers get quickly trapped into these long-lived defect states. However, we remark that a relevant part of electrons remain untrapped: this opens up the opportunity to exploit octapod shaped nanocrystals in photovoltaics applications, as electron acceptor materials, considering that several efficient hole extracting materials are already available for the realization of a composite bulk heterojunction.
authors.affiliation: Center for Nano Science and Technology @ Polimi, Istituto Italiano di Tecnologia, via G. Pascoli 70/3, 20133 Milano, Italy.
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Antognazza
authors.forename: Francesco
authors.initials: F
authors.lastname: Scotognella
authors.forename: Karol
authors.initials: K
authors.lastname: Miszta
authors.forename: Dirk
authors.initials: D
authors.lastname: Dorfs
authors.forename: Marco
authors.initials: M
authors.lastname: Zanella
authors.forename: Margherita
authors.initials: M
authors.lastname: Zavelani-Rossi
authors.forename: Liberato
authors.initials: L
authors.lastname: Manna
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Lanzani
authors.forename: Francesco
authors.initials: F
authors.lastname: Tassone
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D055668:Photochemical Processes; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide