title: Probing the wave function delocalization in CdSe/CdS dot-in-rod nanocrystals by time- and temperature-resolved spectroscopy.
abstract: Colloidal semiconductor quantum structures allow controlling the strong confinement of charge carriers through material composition and geometry. Besides being a unique platform to study fundamental effects, these materials attracted considerable interest due to their potential in opto-electronic and quantum communication applications. Heteronanostructures like CdSe/CdS offer new prospects to tailor their optical properties as they take advantage of a small conduction band offset allowing tunability of the electron delocalization from type-I toward quasi-type-II. Here, we report on a detailed study of the exciton recombination dynamics in CdSe/CdS heterorods. We observed a clear size-dependent radiative lifetime, which can be linked to the different degree of electron wave function (de)localization. Moreover, by increasing the temperature from 70 to 300 K, we observed a considerable increase of the radiative lifetime, clearly demonstrating a reduction of the conduction band offset at higher temperatures. Understanding and controlling electron delocalization in such heterostructures will be pivotal for realizing efficient and low-cost photonic devices.
authors.affiliation: IBM Research Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland. gra@zurich.ibm.com
authors.forename: Gabriele
authors.initials: G
authors.lastname: Rainò
authors.forename: Thilo
authors.initials: T
authors.lastname: Stöferle
authors.forename: Iwan
authors.initials: I
authors.lastname: Moreels
authors.forename: Raquel
authors.initials: R
authors.lastname: Gomes
authors.forename: John S
authors.initials: JS
authors.lastname: Kamal
authors.forename: Zeger
authors.initials: Z
authors.lastname: Hens
authors.forename: Rainer F
authors.initials: RF
authors.lastname: Mahrt
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D019187:Cadmium Compounds; D046911:Macromolecular Substances; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide