Slow Cooling of Hot Polarons in Halide Perovskite Solar Cells

Jarvist Moore Frost, Lucy D. Whalley, Aron Walsh*

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

129 Citations (Scopus)
8 Downloads (Pure)


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
Early online date23 Oct 2017
Publication statusPublished - 8 Dec 2017
Externally publishedYes


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