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Temperature-Independent Dielectric Constant in CsPbBr₃ Nanocrystals Revealed by Linear Absorption Spectroscopy

Shcherbakov-Wu, Wenbi and Sercel, Peter C. and Krieg, Franziska and Kovalenko, Maksym V. and Tisdale, William A. (2021) Temperature-Independent Dielectric Constant in CsPbBr₃ Nanocrystals Revealed by Linear Absorption Spectroscopy. Journal of Physical Chemistry Letters, 12 (33). pp. 8088-8095. ISSN 1948-7185. doi:10.1021/acs.jpclett.1c01822.

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Fundamental photophysical behavior in CsPbBr₃ nanocrystals (NCs), especially at low temperatures, is under active investigation. While many studies have reported temperature-dependent photoluminescence, comparatively few have focused on understanding the temperature-dependent absorption spectrum. Here, we report the temperature-dependent (35–300 K) absorption and photoluminescence spectra of zwitterionic ligand-capped CsPbBr₃ NCs with four different edge lengths (d = 4.9, 7.2, 8.1, and 13.2 nm). The two lowest-energy excitonic transitions are quantitatively modeled over the full temperature range within the effective mass approximation considering the quasi-cubic NC shape and nonparabolicity of the electronic bands. Significantly, we find that the effective dielectric constant determined from the best fit model parameters is independent of temperature. Moreover, we observe a temperature-dependent Stokes shift that saturates at a finite value of Δ ≈ 10 meV at low temperatures for d = 7.2 nm NCs, which is absent in bulk CsPbBr₃ films. Overall, these observations highlight differences between the temperature-dependent dielectric behavior of NC and bulk perovskites and point to the need for a more unified theoretical understanding of absorption and emission in halide perovskites.

Item Type:Article
Related URLs:
URLURL TypeDescription
Shcherbakov-Wu, Wenbi0000-0001-8898-1074
Sercel, Peter C.0000-0002-1734-3793
Krieg, Franziska0000-0002-0370-1318
Kovalenko, Maksym V.0000-0002-6396-8938
Tisdale, William A.0000-0002-6615-5342
Alternate Title:Temperature-Independent Dielectric Constant in CsPbBr3 Nanocrystals Revealed by Linear Absorption Spectroscopy
Additional Information:© 2021 American Chemical Society. Received 8 June 2021. Accepted 9 August 2021. Published online 18 August 2021. Published in issue 26 August 2021. The authors thank Dr. Frank Krumeich for the high-resolution STEM image. Spectroscopic characterization at the Massachusetts Institute of Technology was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, under Contract DE-SC0019345. Theoretical modelling of the exciton level structure was supported as part of the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science, within the DOE. Nanocrystal synthesis and characterization at ETH were supported by the Swiss Federal Commission for Technology and Innovation (CTI-No. 18614.1 PFNM-NM). The authors declare no competing financial interest.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0019345
Swiss Federal Commission for Technology and Innovation18614.1 PFNM-NM
Subject Keywords:Excitons, Absorption, Electrical properties, Perovskites, Temperature dependence
Issue or Number:33
Record Number:CaltechAUTHORS:20210830-230028943
Persistent URL:
Official Citation:Temperature-Independent Dielectric Constant in CsPbBr3 Nanocrystals Revealed by Linear Absorption Spectroscopy Wenbi Shcherbakov-Wu, Peter C. Sercel, Franziska Krieg, Maksym V. Kovalenko, and William A. Tisdale The Journal of Physical Chemistry Letters 2021 12 (33), 8088-8095 DOI: 10.1021/acs.jpclett.1c01822
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110628
Deposited By: George Porter
Deposited On:31 Aug 2021 16:30
Last Modified:31 Aug 2021 16:30

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