Graduate Thesis Or Dissertation

 

The Mechanism of Thermally-Activated Photoluminescence Quenching and Its Correlation with Transport in Electronically-Coupled PbS Quantum Dot Arrays Public Deposited

https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/th83kz73b
Abstract
  • We have measured the temperature-dependent photoluminescence (PL) and quantum yield (QY) of a series of alkanedithiol-treated PbS quantum dot (QD) films as a function of QD size and the length of the alkane chain. These films have PLQYs ranging 2% - 40% at 20 K, with the lowest values measured for shorter ligands and larger QD sizes. All films show PL quenching and shifting/narrowing with increased temperature characterized by exponential (Urbach) band tail behavior. The PLQY vs temperature takes a form derived from an Arrhenius-like dependence of activated charge separation. We also find temperature-dependent photoconductivity (σ), showing an Arrhenius relationship with inverse temperature (T-0.5 at lower temperature matching variable-range hopping model and T-1 at higher temperature corresponding to near-neighbor hopping model), is inversely related with temperature-dependent PL. This indicates that temperature-dependent PL is a relevant measure of transport properties in the presence of deep trap states and reasonably high charge carrier mobilities.
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  • 2013
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Dernière modification
  • 2019-11-18
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