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Correlation of Intermittency of Quantum Dot Photoluminescence Intensity, Decay Time, and Energy
Author(s) -
Göhler Clemens,
Schmidt Robert,
Krasselt Cornelius,
von Borczyskowski Christian
Publication year - 2019
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201800334
Subject(s) - intermittency , quantum dot , photoluminescence , physics , electron , population , atomic physics , molecular physics , condensed matter physics , optoelectronics , quantum mechanics , demography , sociology , turbulence , thermodynamics
Intermittency of photoluminescence (PL) intensity is a common feature of semiconductor quantum dots (QDs). Here, we show for ZnS capped CdSe QDs that the intermittency (blinking) is closely correlated to the intermittency of PL decay times. Furthermore, we find that fluctuations of PL emission energies are also correlated with intensity and decay time blinking. The origin of energy fluctuations is a combination of switching either between energies of electronic states intrinsic to differently charged QDs or correspondingly Stark shifted states caused by slow fluctuations of the QD interface. By the method of change point analysis we assign the distribution of PL intensities intermediate between on/off intensities to distinct intermittent PL decay times and PL energies. Intermittency occurs on slow time scales between sub‐ms and minutes and depends strongly on the embedding matrix. Highly specific experiments allow for identification of a distribution of charged and non‐charged states near to the excitonic band edge. Most of the blinking phenomena are observed on the depopulation pathways of the band edge states. However, also population pathways are intermittent, but on a much shorter time scale. We assign this mechanism to creation of hot electrons followed by charge trapping and release at the QD interface.