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ALT'22 — LD-0-1
LASER DIAGNOSTICS AND SPECTROSCOPY
Electron-phonon coupling in the ensemble of colloidal quantum dots: combined study by spectral and time-resolved methods
A. I. Arzhanov1,2,3, K. R. Karimullin12,3, I. Yu. Eremchev12,3, N. V. Surovtsev4, A. V. Naumov1,2,3
1- Moscow Pedagogical State University, 29 Malaya Pirogovskaya str., 119992 Moscow, Russia 2- Lebedev Physical Institute, Russian Academy of Sciences, Branch in Troitsk, 11 Fizicheskaya str.,
142190 Moscow, Troitsk, Russia 3-Institute for Spectroscopy, Russian Academy of Science, 5 Fizicheskaya str., 142190 Moscow, Troitsk, Russia 4-Institute of Automation and Electrometry, Siberian Branch Russian Academy of Sciences,1 acad. Koptyuga str.,
630090 Novosibirsk, Russia arzhanov. [email protected]
Semiconductor quantum dots (QD) are interesting objects due to their unique features [1,2]. In particular, the quantum size effect is observed in colloidal quantum dots. This effect makes it possible to obtain nanocrystals at the stage of synthesis different sizes and spectral properties. Such properties include variation in the position of the luminescence maximum, high photostability, and a wide absorption contour. Based on these properties, QDs are already used as phosphors for LEDs. They can also be used for medicine (as markers) and in photovoltaics. QDs can be embedded into various amorphous media as probes. Due to local field effects, single QDs are a very sensitive instrument to environmental parameters. The creation of various materials, such as QD-based composites, is of great importance in materials science, because such nanocomposites can have both optical and mechanical properties.
In this paper, we present combined methods for spectral diagnostics of local parameters of nanocomposites based on QD [3]. The parameters of the electron-phonon coupling were studied by measuring the temperature dependences of the exciton luminescence spectra for colloidal CdSe/CdS/ZnS quantum dots on a glass substrate and composites based on QD. Using the Varshni equation [4] for the temperature dependences of the band gap in bulk semiconductors, one can obtain a limited number of internal parameters. Using O'Donnell and Chen equation [5], it was possible to obtain the band gap parameters at zero temperature, Huang-Rhys factor and average phonon energy (ELO = 21.4 meV). The last parameter correlates with direct Raman scattering measurements (ELO = 25 meV) and also with photon echo experiments, where phase relaxation times were observed [6].
The work was carried out within the framework of the State Assignment of the Moscow Pedagogical State University (MPGU) "Physics of Nanostructured Materials: Fundamental Research and Applications in Materials Science, Nanotechnology and Photonics" with the support of the Ministry of Education of the Russian Federation (AAAA-A20-120061890084-9) together with the Centre for Collective Use "Structural Diagnostics of Materials" of the Federal Research Centre of the Russian Academy of Sciences "Crystallography and Photonics". The authors are members of the Leading Scientific School of the Russian Federation (grant of the President of the Russian Federation NSh- 776.2022.1.2
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[3] K R Karimullin, A I Arzhanov, I Yu Eremchev, B A Kulnitskiy, N V Surovtsev and A V Naumov, Combined photon-echo, luminescence and Raman spectroscopies of layered ensembles of colloidal quantum dots, Laser Physics, 12, 29, p. 124009, (2019).
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