Article,

Thermal Conductivity of CH3NH3PbI3 and CsPbI3: Measuring the Effect of the Methylammonium Ion on Phonon Scattering

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The Journal of Physical Chemistry C, 121 (6): 3228-3233 (2017)
DOI: 10.1021/acs.jpcc.6b12231

Abstract

Temperature-dependent thermal conductivity in the range between 7 and 300 K was measured for CH3NH3PbI3 and CsPbI3 and compared to a Debye model via the Callaway method. Thermal conductivity was found to be extremely low across the whole temperature range for both materials, with CH3NH3PbI3 lower than CsPbI3. Fitting analysis showed that a resonant phonon scattering term can account for the difference in thermal transport behavior between the perovskite with a methylammonium (MA) ion versus a single cesium atom in the cationic A site of the lattice. The resonant frequency associated with this term is in the range of ∼15–30 cm–1, pointing to the rotational degree of freedom of the organic ion. Analysis of the temperature dependence of the possible phonon scattering mechanisms showed that thermal conductivity of both CH3NH3PbI3 and CsPbI3 perovskites was dominated by Umklapp scattering at room temperature, and the rotation of the organic cation may be responsible for suppressing the thermal conductivity of CH3NH3PbI3 in comparison with CsPbI3, particularly at low temperatures, ∼25 K. This work presents the first determination of temperature-dependent thermal conductivity of CsPbI3.

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