title: Temperature-sensitive photoluminescence of CdSe quantum dot clusters.
abstract: The formation of narrow size dispersed and nanometer size aggregates (clusters) of cadmium selenide (CdSe) quantum dots (QDs) and their temperature-sensitive photoluminescence (PL) spectral properties close to room temperature (298 K) are discussed. CdSe QDs formed stable clusters with an average diameter of approximately 27 nm in the absence of coordinating solvents. Using transmission electron microscopy (TEM) imaging, we identified the association of individual QDs with 2-5 nm diameters into clusters of uniform size. A suspension of these clusters in different solvents exhibited reversible PL intensity changes and PL spectral shifts which were correlated with temperature. Although the PL intensity of CdSe QDs encapsulated in host matrixes and the solid state showed a response to temperature under cryogenic conditions, the current work identified for the first time QD clusters showing temperature-sensitive PL intensity variations and spectral shifts at moderate temperatures above room temperature. Temperature-sensitive reversible PL changes of clusters are discussed with respect to reversible thermal trapping of electrons at inter-QD interfaces and dipole-dipole interactions in clusters. Reversible luminescence intensity variations and spectral shifts of QD clusters show the potential for developing sensors based on QD nanoscale assemblies.
authors.affiliation: Nano-Bioanalysis Team, Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan. v.biju@aist.go.jp
authors.forename: Vasudevanpillai
authors.initials: V
authors.lastname: Biju
authors.forename: Yoji
authors.initials: Y
authors.lastname: Makita
authors.forename: Akinari
authors.initials: A
authors.lastname: Sonoda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokoyama
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Baba
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ishikawa
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D049449:Luminescence; D008163:Luminescent Measurements; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D010777:Photochemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013696:Temperature
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide