Luminescent surface-modified CDSE

Figure 12.2 Effect of the addition of 0.65 mg L 1 cyanide on the luminescence emission spectra of surface-modified CdSe QDs.

They found good agreement between experiment and theory for surface-modified CdSe nanocrystallites. This agreement suggests that the band edge luminescence of CdSe QDs can be quantitatively understood using an intrinsic exciton model and that the role of the surface in the optical properties of the QDs lies in its defects which create deep red radiative and nonra-diative pathways for recombination of the electron and hole upon photoexcitation of the nanocrystallite [6]. 

Binder, W.H., Sachsenhofer, R., Straif, C.J., andZirbs, R. (2007d) Surface-modified nanoparticles via thermal and Cu (i)-mediated click chemistry Generation of luminescent CdSe nanoparticles with polar ligands guiding supramolecular recognition. Journal of Materials Chemistry, 17,2125-2132. 

Customarily, semiconductor surfaces are chemically or physically prepared to optimize their chemical and/or electro-optical properties. For chemical sensing applications, a freshly etched surface often provides greater chemical sensitivity. A Br2/MeOH etch of n-CdSe, for example, has typically yielded larger luminescence responses to analytes than have polished samples. Additionally, transducing films have been used to modify semiconductor surfaces to enhance the selectivity of CdSe for particular analytes [2]. 

PMMA modified by inorganic nanoparticles such as Ti02, ZnS Mn, CdSe, CdSe/ZnS, ZnO, and CNTs has led to enhanced optical [16], thermal [149], and electrical properties, as compared to pure polymer. For example, Althues et al. [16] reported an efficient method for generation of completely transparent and strongly luminescent ZnS Mn/PMMA nanocomposites. They used in-situ bulk polymerization of transparent dispersions containing ZnS Mn nanoparticles in a mixture of MMA and AA the effective diameter of nanoparticles in the monomer dispersion was 22 nm. Two factors were responsible for the stability of the ZnS Mn/monomer dispersion, i.e., coordination of AA, which modified the surface of the nanoparticles and led to hydrophobization, and adsorption of ions leading to a surface charge... 

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