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Moreels I, Lambert K, Smeets D, et al. Size-dependent optical properties of colloidal PbS quantum dots. ACS Nano. 2009;3(10):3023-30doi: 10.1021/nn900863a.
Moreels, I., Lambert, K., Smeets, D., De Muynck, D., Nollet, T., Martins, J. C., Vanhaecke, F., Vantomme, A., Delerue, C., Allan, G., & Hens, Z. (2009). Size-dependent optical properties of colloidal PbS quantum dots. ACS nano, 3(10), 3023-30. https://doi.org/10.1021/nn900863a
Moreels, Iwan, et al. "Size-dependent optical properties of colloidal PbS quantum dots." ACS nano vol. 3,10 (2009): 3023-30. doi: https://doi.org/10.1021/nn900863a
Moreels I, Lambert K, Smeets D, De Muynck D, Nollet T, Martins JC, Vanhaecke F, Vantomme A, Delerue C, Allan G, Hens Z. Size-dependent optical properties of colloidal PbS quantum dots. ACS Nano. 2009 Oct 27;3(10):3023-30. doi: 10.1021/nn900863a. PMID: 19780530.
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ACS Nano. 2009 Oct 27;3(10):3023-30. doi: 10.1021/nn900863a.

Size-dependent optical properties of colloidal PbS quantum dots.

ACS nano

Iwan Moreels, Karel Lambert, Dries Smeets, David De Muynck, Tom Nollet, José C Martins, Frank Vanhaecke, André Vantomme, Christophe Delerue, Guy Allan, Zeger Hens

Affiliations

  1. Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S12, B-9000 Ghent, Belgium. [email protected]

PMID: 19780530 DOI: 10.1021/nn900863a

Abstract

We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient epsilon increases with the Qdot volume d(3) and agrees with theoretical calculations using the Maxwell-Garnett effective medium theory and bulk values for the Qdot dielectric function. This demonstrates that quantum confinement has no influence on epsilon in this spectral range, and it provides an accurate method to calculate the Qdot concentration. Around the band gap, epsilon only increases with d(1.3), and values are comparable to the epsilon of PbSe Qdots. The data are related to the oscillator strength f(if) of the band gap transition and results agree well with theoretical tight-binding calculations, predicting a linear dependence of f(if) on d. For both PbS and PbSe Qdots, the exciton lifetime tau is calculated from f(if). We find values ranging between 1 and 3 mus, in agreement with experimental literature data from time-resolved luminescence spectroscopy. Our results provide a thorough general framework to calculate and understand the optical properties of suspended colloidal quantum dots. Most importantly, it highlights the significance of the local field factor in these systems.

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