Near infrared emission from monomodal and bimodal PbS nanocrystal superlattices

Michela Corricelli, Francesco Enrichi, Davide Altamura, Liberato De Caro, Cinzia Giannini, Andrea Falqui, Angela Agostiano, M. Lucia Curri, Marinella Striccoli*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


PbS colloidal nanocrystal (NC) assemblies with monomodal and bimodal size distribution have been fabricated by slow evaporation of solvent on silicon substrates. The interparticle distances of the assembled structures have been carefully defined, both in the plane and in the z direction, perpendicular to the substrate, thanks to the combination of small and wide-angle X-ray diffraction and TEM measurements. The spectroscopic characteristics of PbS NCs, both in solution and organized in a superlattice, have been investigated by steady-state and time-resolved photoluminescence measurements. The optical results reveal the occurrence of a Förster resonant energy transfer (FRET) mechanism between closed-packed neighboring PbS NCs. The occurrence of FRET is dependent on NC assembly geometry, and thus on their interparticle distance, suggesting that only when NCs are close enough, as in the close-packed arrangement of the monomodal assembly, the energy transfer can be promoted. In bimodal assemblies, the energy transfer between large and small NCs is negligible, due to the low spectral overlap between the emission and absorption bands of the different sized nanoparticles and to the large interparticle distance. Moreover, recombination lifetimes on the microsecond time scale have been observed and explained in terms of dielectric screening effect, in agreement with previous findings on lead chalcogenide NC optical properties.

Original languageEnglish (US)
Pages (from-to)6143-6152
Number of pages10
Issue number10
StatePublished - Mar 15 2012
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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