Coupling to octahedral tilts in halide perovskite nanocrystals induces phonon-mediated attractive interactions between excitons
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 FAPbBr₃. Our results indicate a stronger coupling in FAPbBr₃ than CsPbBr₃. We attribute the enhanced coupling in FAPbBr₃ 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. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000644589Publication status
publishedExternal links
Journal / series
Nature PhysicsVolume
Pages / Article No.
Publisher
NatureOrganisational unit
03934 - Kovalenko, Maksym / Kovalenko, Maksym
09701 - Yarema, Maksym / Yarema, Maksym
Funding
175889 - Multi-length Scale Engineering of Thermal Properties of Nanocrystals and their Composite Films: Fundamentals and Applications (SNF)
200021_156011 - Hierarchical carbon-fiber composites with tailored interphase obtained via electrophoretic deposition of magnetized and funtionalized carbon nanotubes (SNF)
192308 - Q-Light - Engineered Quantum Light Sources with Nanocrystal Assemblies (SNF)
852751 - Solution-Based Engineering of Nanodimensional Phase-Change Materials and Memory Devices (EC)
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