Slow cooling of hot polarons in halide perovskite solar cells
| Autor: | Frost, Jarvist Moore, Whalley, Lucy D., Walsh, Aron |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | ACS Energy Letters 2, 2647-2652 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/acsenergylett.7b00862 |
| Popis: | Halide perovskites show unusual thermalisation kinetics for above bandgap photo-excitation. We explain this as a consequence of excess energy being deposited into discrete large polaron states. The cross-over between low-fluence and high-fluence `phonon bottleneck' cooling is due to a Mott transition where the polarons overlap ($n \ge 10^{18}/\mathrm{cm}^3$) and the phonon sub-populations are shared. We calculate the initial rate of cooling (thermalisation) from the scattering time in the Fr\"ohlich polaron model to be 78 meVps$^{-1}$ for $\mathrm{CH}_3\mathrm{NH}_3\mathrm{PbI}_3$. This rapid initial thermalisation 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 ultra-low thermal conductivity of the perovskite lattice. Comment: 7 pages, 1 schematic, 3 figures |
| Databáze: | arXiv |
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