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Coupling to octahedral tilts in halide perovskite nanocrystals induces phonon-mediated attractive interactions between excitons

Published inNature physics, vol. 20, no. 1, p. 47-53
Publication date2023-11-09
First online date2023-11-09
Abstract

Understanding the origin of electron–phonon coupling in lead halide perovskites is key to interpreting and leveraging their optical and electronic properties. Here we show that photoexcitation drives a reduction of the lead–halide–lead bond angles, a result of deformation potential coupling to low-energy optical phonons. We accomplish this by performing femtosecond-resolved, optical-pump–electron-diffraction-probe measurements to quantify the lattice reorganization occurring as a result of photoexcitation in nanocrystals of FAPbBr 3 . Our results indicate a stronger coupling in FAPbBr 3 than CsPbBr 3 . We attribute the enhanced coupling in FAPbBr 3 to its disordered crystal structure, which persists down to cryogenic temperatures. We find the reorganizations induced by each exciton in a multi-excitonic state constructively interfere, giving rise to a coupling strength that scales quadratically with the exciton number. This superlinear scaling induces phonon-mediated attractive interactions between excitations in lead halide perovskites.

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Keywords
  • Electronic devices
  • Electronic properties and materials
  • Quantum dots
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Citation (ISO format)
YAZDANI, Nuri et al. Coupling to octahedral tilts in halide perovskite nanocrystals induces phonon-mediated attractive interactions between excitons. In: Nature physics, 2023, vol. 20, n° 1, p. 47–53. doi: 10.1038/s41567-023-02253-7
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ISSN of the journal1745-2473
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