Long Exciton Dephasing Time and Coherent Phonon Coupling in CsPbBr${}_2$Cl Perovskite Nanocrystals

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 timescale, determining dephasing and density decay rates in these NCs. The experiments are performed on CsPbBr${}_2$Cl NCs using transient resonant three-pulse four-wave mixing (FWM) in heterodyne detection at temperatures ranging from 5 K to 50 K. We found a low-temperature exciton dephasing time of 24.5$\pm$1.0 ps, inferred from the decay of the photon-echo amplitude at 5 K, corresponding to a homogeneous linewidth (FWHM) of 54$\pm$5 μeV. Furthermore, oscillations in the photon-echo signal on a picosecond timescale are observed and attributed to coherent coupling of the exciton to a quantized phonon mode with 3.45 meV energy.

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• Circularly Polarized Luminescence Without External Magnetic Fields from Individual CsPbBr3 Perovskite Quantum Dots
• Anomalous diffusion in the Long-Range Haken-Strobl-Reineker model
• An Exact Expression for Multidimensional Spectroscopy of a Spin-Boson Hamiltonian
• Sub-nanosecond coherent optical manipulation of a single aromatic molecule at cryogenic temperature
• Measuring Exciton Fine-Structure in Perovskite Nanocrystal Ensembles
• Transition between cooperative emission regimes in giant perovskite nanocrystals
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