Acoustic-optical phonon up-conversion and hot-phonon bottleneck in lead-halide perovskites
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Date
2017
Authors
Yang, J.
Wen, X.
Xia, H.
Sheng, R.
Ma, Q.
Kim, J.
Tapping, P.
Harada, T.
Kee, T.
Huang, F.
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Journal article
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Nature Communications, 2017; 8(1):14120-1-14120-9
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Jianfeng Yang, Xiaoming Wen, Hongze Xia, Rui Sheng, Qingshan Ma, Jincheol Kim, Patrick Tapping, Takaaki Harada, Tak W. Kee, Fuzhi Huang, Yi-Bing Cheng, Martin Green, Anita Ho-Baillie, Shujuan Huang, Santosh Shrestha, Robert Patterson, Gavin Conibeer
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Abstract
The hot-phonon bottleneck effect in lead-halide perovskites (APbX3) prolongs the cooling period of hot charge carriers, an effect that could be used in the next-generation photovoltaics devices. Using ultrafast optical characterization and first-principle calculations, four kinds of lead-halide perovskites (A=FA(+)/MA(+)/Cs(+), X=I(-)/Br(-)) are compared in this study to reveal the carrier-phonon dynamics within. Here we show a stronger phonon bottleneck effect in hybrid perovskites than in their inorganic counterparts. Compared with the caesium-based system, a 10 times slower carrier-phonon relaxation rate is observed in FAPbI3. The up-conversion of low-energy phonons is proposed to be responsible for the bottleneck effect. The presence of organic cations introduces overlapping phonon branches and facilitates the up-transition of low-energy modes. The blocking of phonon propagation associated with an ultralow thermal conductivity of the material also increases the overall up-conversion efficiency. This result also suggests a new and general method for achieving long-lived hot carriers in materials.
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© The Author(s) 2017. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/