Temperature-dependent emission kinetics of colloidal semiconductor nanoplatelets strongly modified by stacking
Date
2016Source Title
Journal of Physical Chemistry Letters
Print ISSN
1948-7185
Publisher
American Chemical Society
Volume
7
Issue
3
Pages
548 - 554
Language
English
Type
ArticleItem Usage Stats
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Abstract
We systematically studied temperature-dependent emission kinetics in solid films of solution-processed CdSe nanoplatelets (NPLs) that are either intentionally stacked or nonstacked. We observed that the steady-state photoluminescence (PL) intensity of nonstacked NPLs considerably increases with decreasing temperature, whereas there is only a slight increase in stacked NPLs. Furthermore, PL decay time of the stacked NPL ensemble is comparatively much shorter than that of the nonstacked NPLs, and this result is consistent at all temperatures. To account for these observations, we developed a probabilistic model that describes excitonic processes in a stack using Markov chains, and we found excellent agreement between the model and experimental results. These findings develop the insight that the competition between the radiative channels and energy transfer-assisted hole trapping leads to weakly temperature-dependent PL intensity in the case of the stacked NPL ensembles as compared to the nonstacked NPLs lacking strong energy transfer. This study shows that it is essential to account for the effect of NPL stacking to understand their resulting PL emission properties.
Keywords
Markov processesColloidal semiconductors
Kinetics in solids
Nano-platelets
Photoluminescence intensities
Probabilistic modeling
Radiative channels
Solution-processed
Temperature dependent
Energy transfer