CdSe dots

Krauss and Brus [15] measured the dielectric constant of CdSe dots, and found a value of 8. Hence, at room temperature we find r0ns — 70 A (angstrom) (however, note that the dielectric constant of the matrix is not identical to that of the dot). Since the length scale of the dots is of the order of a few nanometers, the Coulomb interaction seems to be an important part of the problem. This according to the theory in Ref. 16 is an indication of possible deviations from the universal 1 /2 power-law behavior. It is also an indication that an ejected electron is likely to return to the dot and not escape to the bulk (since the force is attractive). In contrast, if the Onsager radius is small, an ejected electron would most likely escape to the bulk, leaving the dot in state off forever (i.e., Polya... 

Figure 16 Seeding CdSe NQD rod growth for improved size monodispersity. (a) TEM of CdSe dots prepared in 13% TDPA using an injection temperature of 360 °C and a growth temperature of 250 °C. (b) TEM of NQD rods grown from the dot seeds following injection of additional monomer (c) TEM of NQD rods after 23 h of growth, (d) XRD pattern for CdSe rods from (c). (Reprinted with permission from Ref 12. 2001 American Chemical Society)...

Fig.5.3-ft (a) Low-temperature (10 K) absorption spectra of CdSe dots dispersed in a polymer matrix, for various mean diameters. (b) Nanosecond saturated-absorption spectra for 67 A dots. The pump beam had a 7 ns FWHM. The excitation photon energy, 1.984 eV, is prolonged as a dashed vertical line from (a) for easier comparison. The horizontal dashed line corresponds to AOD = 0. (c),(d) Photoluminescence(PL) and photoluminescence-excitation(PLE, observed at 2.022 eV) spectra for 67 A dots (c) and for 62 A dots (d). (After [3.29])... 

C. Trallero-Giner, A. Debernardi, M. Cardona, E. Menendez-Proupin, A.I. Ekimov, Optical vibrons in CdSe dots and dispersion relation of the bulk material. Phys. Rev. B 57(8), 4664 669 (1998)... 

Empedocles S A, Norris D J and Bawendi M G 1996 Photoluminescence spectroscopy of single CdSe nanocrystallite quantum dots Phys. Rev. Lett. 77 3873-6... 

Empedocles S A and Bawendi M G 1997 Quantum-confined Stark effect in single CdSe nanocrystalline quantum dots Science 278 2114-17... 

Dabbousi B O ef a/1997 (CdSe)ZnS oore-shell quantum dots synthesis and oharaoterization of a size series of highly luminesoent nanoorystallites J. Phys. Chem. B 101 9463... 

Murray C B, Kagan C R and Bawendi M G 1995 Self-organization of CdSe nanoorystallites into three-dimensional quantum dot superlattioes Science 270 1335... 

Electroluminescence from CdSe quantum dot / polymer composite. App/. Phys. Lett, 66,1316-1318. 

Core/shell-type nanoparticles ovm ated with higher band inorganic materials exhibit high PL quantum yield compared with uncoated dots d K to elimination of surface non-radiative recombination defects. Such core/shell structures as CdSe/CdS [6] and CdSe ZnS [7] have been prepared from organometaHic precursors. 

The fundamental issue of epitaxial growth on polycrystalline substrates has been addressed in a more refined manner in relation to the electrodeposition of CdSe on metals. Polycrystalline, lll -textured Au surfaces were shown [17] to promote the electrodeposition of coherent, epitaxial CdSe quantum dot films over areas micrometers in size, i.e., much larger than the polycrystalline Au grains, despite the numerous grain boundaries present in the substrate. The Au films (considered as... 

Golan Y, Alperson B, Hutchison JL, Hodes G, Rubinstein I (1997) Electrodeposited quantum dots Coherent nanocrystalhne CdSe on oriented polycrystalline Au films. Adv Mater 9 ... 

Zhang Y, Hodes G, Rubinstein I, Griinbaum E, Nayak RR, Hutchison JL (1999) Electrodeposited quantum dots Metastable rocksalt CdSe nanocrystals on 111 gold alloys. Adv Mater 11 1437-1441... 

Ruach-Nir I, Wagner HD, Rubinstein I, Hodes G (2003) Structural effects in the electrodeposition of CdSe quantum dots on mechanically strained gold. Adv Eunct Mater 13 159-164... 

Fig. 5.19 (a) Linking CdSe quantum dots to Ti02 particle with bifunctional surface modifier (b) light harvesting assembly composed of T102 film functionahzed with CdSe Q-dots on optically transparent electrode (OTE). [Adapted (in gray scale) from [348]]... 

Fig. 5.20 Schematic diagram illustrating the energy levels of different-sized CdSe quantum dots and Ti02 (band positions are not drawn to scale). The injection of electrons from CdSe into Ti02 is influenced by the energy difference between the two conduction bands. [Adapted (in gray scale) from [351]]...

Kim S, Fisher B, Eisler HJ, Bawendi M (2003) Type-11 Quantum Dots CdTe/CdSe (core/sheU) and CdSe/ZnTe(core/shell) heterostructures. J Am Chem Soc 125 11466-11467 Aharoni A, Mokaii T, Popov 1, Banin U (2006) Synthesis of InAs/CdSe/ZnSe core/ shelll/shell2 structures with bright and stable near-infrared fluorescence. J Am Chem Soc 128 257-264... 

Toyoda T, Tsuboya 1, Shen Q (2005) Effect of rutile-type content on nanostructured anatase-type Ti02 electrode sensitized with CdSe quantum dots characterized with photoacoustic and photoelectrochemical current spectroscopies. Mater Sci Eng C 25 853-857... 

Toyoda T, Kobayashi J, Shen Q (2008) Correlation between crystal growth and photosensitization of nanostructured HO2 electrodes using supporting H substrates by self-assembled CdSe quantum dots. Thin SoUd Films 516 2426-2431... 

Shen Q, Arae D, Toyoda T (2004) Photosensitization of nanostructured TiOa with CdSe quantum dots effects of microstructure and electron transport in HO2 substrates. J Photoch Photobio A 164 75-80... 

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