Long exciton dephasing time and coherent phonon coupling in CsPbBr2Cl perovskite nanocrystals

Becker, Michael A., Scarpelli, Lorenzo, Nedelcu, Georgian, Raino, Gabriele, Masia, Francesco ORCID: https://orcid.org/0000-0003-4958-410X, Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314, Stöferle, Thilo, Kovalenko, Maksym V., Langbein, Wolfgang ORCID: https://orcid.org/0000-0001-9786-1023 and Mahrt, Rainer F. 2018. Long exciton dephasing time and coherent phonon coupling in CsPbBr2Cl perovskite nanocrystals. Nano Letters 18 (12) , pp. 7546-7551. 10.1021/acs.nanolett.8b03027

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Abstract

Fully inorganic cesium lead halide perovskite nanocrystals (NCs) have shown to exhibit outstanding optical properties such as wide spectral tunability, high quantum yield, high oscillator strength as well as blinking-free single photon emission, and low spectral diffusion. Here, we report measurements of the coherent and incoherent exciton dynamics on the 100 fs to 10 ns time scale, determining dephasing and density decay rates in these NCs. The experiments are performed on CsPbBr2Cl NCs using transient resonant three-pulse four-wave mixing (FWM) in heterodyne detection at temperatures ranging from 5 to 50 K. We found a low-temperature exciton dephasing time of 24.5 ± 1.0 ps, inferred from the decay of the photon-echo amplitude at 5 K, corresponding to a homogeneous line width (fwhm) of 54 ± 5 μeV. Furthermore, oscillations in the photon-echo signal on a picosecond time scale are observed and attributed to coherent coupling of the exciton to a quantized phonon mode with 3.45 meV energy.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy Biosciences
Additional Information:	@ACS AuthorChoice with CC-BY license
Publisher:	American Chemical Society
ISSN:	1530-6984
Date of First Compliant Deposit:	14 November 2018
Date of Acceptance:	8 November 2018
Last Modified:	06 May 2023 11:16
URI:	https://orca.cardiff.ac.uk/id/eprint/116787

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