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Octahedral Distortions Generate a Thermally Activated Phonon-Assisted Radiative Recombination Pathway in Cubic
Vivien L Cherrette1, Finn Babbe2, Jason K Cooper2
1Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States.
The Journal of Physical Chemistry Letters
|September 22, 2023
Summary
Exciton-phonon interactions in cubic perovskite quantum dots (PQDs) cause performance issues like line width broadening. Minimizing these interactions at cryogenic temperatures improves optical emitter performance.
Area of Science:
- Materials Science
- Solid-State Physics
- Quantum Optics
Background:
- Exciton-phonon interactions are crucial for controlling optical properties in solid-state emitters.
- Understanding these interactions is key to designing high-performance optical devices.
Purpose of the Study:
- To investigate the role of exciton-phonon interactions in cubic CsPbBr3 perovskite quantum dots (PQDs).
- To elucidate the relationship between structural distortions and optical performance degradation.
Main Methods:
- Temperature-dependent steady-state photoluminescence (PL) and time-resolved PL (TRPL) spectroscopy.
- Analysis of structural distortions in PbBr6 octahedra.
Main Results:
- Thermally activated exciton-phonon interactions, driven by PbBr6 octahedral distortions, cause PL line width broadening and slower recombination in cubic PQDs at room temperature.
- These interactions lead to symmetry breaking and coupling with longitudinal optical (LO) phonons.
- Line width broadening is reduced at cryogenic temperatures due to decreased phonon-assisted recombination.
Conclusions:
- Intrinsic exciton-phonon interactions are a primary cause of performance degradation in PQD optical emitters.
- Understanding these interactions provides insight into the cubic phase's polymorphic nature and strategies for performance enhancement.
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