Multilayers of Carbodithioate and Sulfide-Linked CdSe Nanocrystals: Progressive Increase of Exciton Delocalization

Multilayers of sulfur-based anchoring group linkers and CdSe nanocrystals (NCs) were realized on indium-tin oxide substrate via layer-by-layer alternation. The materials were investigated by UV–vis and Fourier transform infrared spectroscopy, photoluminescence, and photoconductivity. We found that t...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2019-09, Vol.123 (37), p.23159-23166
Main Authors: Vercelli, B, Virgili, T, Pasini, M, Berlin, A, Zotti, G
Format: Article
Language:English
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Summary:Multilayers of sulfur-based anchoring group linkers and CdSe nanocrystals (NCs) were realized on indium-tin oxide substrate via layer-by-layer alternation. The materials were investigated by UV–vis and Fourier transform infrared spectroscopy, photoluminescence, and photoconductivity. We found that the change of NC packing during multilayer build-up produces a progressive increase of exciton delocalization. In fact during multilayer deposition, the first excitonic peak of NCs shifts progressively toward longer wavelengths. We found a linear relation between the optical band gap shift (ΔE gn ) and the inverse of the number of CdSe-NC layers (n) for n > 2, in particular, the decrease of its value for the infinite multilayer from one of the solution (2.10 eV) goes from 18 meV for the 1,2-ethylene-bis­(dithiocarbamate) linker to 66 meV for sulfide dianions, corresponding to an apparent increase of the exciton radius of 0.20 and 0.85 nm, respectively.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.9b04276