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Phase segregation in mixed-halide perovskites affects charge-carrier dynamics while preserving mobility
Silvia G Motti1, Jay B Patel1, Robert D J Oliver1
1Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom.
Nature Communications
|November 30, 2021
Summary
Illumination-induced phase segregation in mixed halide perovskites minimally impacts charge-carrier mobility. Surprisingly, fast charge funnelling into iodide-rich domains occurs, suggesting light management can mitigate solar cell performance losses.
Area of Science:
- Materials Science
- Solid-State Physics
- Photovoltaics
Background:
- Mixed halide perovskites offer tunable bandgaps crucial for efficient tandem solar cells.
- Illumination can trigger phase segregation in these materials, potentially impacting device performance.
Purpose of the Study:
- Investigate the effects of halide segregation on charge-carrier dynamics and transport in mixed halide perovskite films.
- Understand the mechanisms behind charge carrier behavior post-segregation.
Main Methods:
- Utilized optical-pump terahertz-probe spectroscopy.
- Analyzed charge-carrier dynamics and transport properties.
- Examined lattice anharmonicity and phonon effects.
Main Results:
- Halide segregation showed negligible impact on terahertz charge-carrier mobilities.
- Charge carriers in iodide-rich phases were not strongly localized.
- Enhanced lattice anharmonicity in iodide-rich domains was observed, suggesting ionic migration support.
- Evidence of rapid, picosecond charge funnelling into narrow-bandgap iodide-rich domains was found.
Conclusions:
- Minimal structural changes during phase segregation significantly alter charge-carrier dynamics via charge funnelling.
- Enhanced recombination, being radiative, suggests performance losses in solar cells can be mitigated through advanced light management strategies.
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