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Kinetics and Thermodynamics of Killing a Quantum Dot
Light-emitting nanocrystal quantum dots (QDs) are of high interest for use as down-conversion phosphors and direct emission sources in bulk solid-state devices and as reliable sources of single photons in quantum information science. However, these materials are prone to photooxidation that reduces...
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Published in: | ACS applied materials & interfaces 2020-07, Vol.12 (27), p.30695-30701 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Light-emitting nanocrystal quantum dots (QDs) are of high interest for use as down-conversion phosphors and direct emission sources in bulk solid-state devices and as reliable sources of single photons in quantum information science. However, these materials are prone to photooxidation that reduces the emission quantum yield over time. Current commercial applications use device architectures to prevent oxidation without addressing the underlying degradation reactions at the nanocrystal level. To instead prevent loss of functionality by better synthetic engineering of the nanoscale emitters themselves, the underlying properties of these reactions must be understood and readily accessible. Here, we use solid-state spectroscopy to obtain kinetic and thermodynamic parameters of photothermal degradation in single QDs by systematically varying the ambient temperature and photon pump fluence. We describe the resulting degradation in emission with a modified form of the Arrhenius equation and show that this reaction proceeds via pseudo-zero-order reaction kinetics by a surface-assisted process with an activation energy of 60 kJ/mol. We note that the rate of degradation is ∼12 orders of magnitude slower than the rate of excitonic processes, indicating that the reaction rate is not determined by electron or hole trapping. In the search for new robust light-emitting nanocrystals, the reported analysis method will enable direct comparisons between differently engineered nanomaterials. |
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ISSN: | 1944-8244 1944-8252 |
DOI: | 10.1021/acsami.0c05980 |