Slow Cooling of Hot Polarons in Halide Perovskite Solar Cells

Jarvist Moore Frost, Lucy D. Whalley, Aron Walsh

Research output: Contribution to journalArticlepeer-review

111 Citations (Scopus)


Halide perovskites show unusual thermalization kinetics for above-bandgap photoexcitation. We explain this as a consequence of excess energy being deposited into discrete large polaron states. The crossover between low-fluence and high-fluence "phonon bottleneck" cooling is due to a Mott transition where the polarons overlap (n ≥ 1018 cm-3) and the phonon subpopulations are shared. We calculate the initial rate of cooling (thermalization) from the scattering time in the Fröhlich polaron model to be 78 meV ps-1 for CH3NH3PbI3. This rapid initial thermalization involves heat transfer into optical phonon modes coupled by a polar dielectric interaction. Further cooling to equilibrium over hundreds of picoseconds is limited by the ultralow thermal conductivity of the perovskite lattice.

Original languageEnglish
Pages (from-to)2647-2652
Number of pages6
JournalACS Energy Letters
Issue number12
Publication statusPublished - 2017 Dec 8

Bibliographical note

Funding Information:
We thank Jonathan M. Skelton for discussions concerning the thermal conductivity calculations. Via our membership of the UK’s HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service ( This work was funded by the EPSRC (Grant Numbers EP/ L01551X/1, EP/L000202, and EP/K016288/1), the Royal Society, and the ERC (Grant No. 277757).

Publisher Copyright:
© 2017 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry


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