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Title: Photoluminescence quantum yield of PbS nanocrystals in colloidal suspensions

The absolute photoluminescence (PL) quantum yield (QY) of oleic acid-capped colloidal PbS quantum dots (QDs) in toluene is thoroughly investigated as function of QD size, concentration, excitation photon energy, and conditions of storage. We observed anomalous decrease of QY with decreasing concentration for highly diluted suspensions. The ligand desorption and QD-oxidation are demonstrated to be responsible for this phenomenon. Excess of oleic acid in suspensions makes the QY values concentration-independent over the entire reabsorption-free range. The PL emission is shown to be dominated by surface-related recombinations with some contribution from QD-core transitions. We demonstrate that QD colloidal suspension stability improves with increasing the concentration and size of PbS QDs.
Authors:
; ;  [1]
  1. Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Prague 2, CZ-121 16 Czech Republic (Czech Republic)
Publication Date:
OSTI Identifier:
22402845
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 14; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONCENTRATION RATIO; DESORPTION; EXCITATION; LEAD SULFIDES; LIGANDS; OLEIC ACID; OXIDATION; PHASE STABILITY; PHOTOLUMINESCENCE; PHOTONS; QUANTUM DOTS; SURFACES; SUSPENSIONS; TOLUENE; YIELDS