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Description
Organic-inorganic hybrid perovskites are promising active materials for optoelectronic and photovoltaic applications due to their large exciton binding energy, long carrier diffusion length, and tunable band gap [1-3]. Interestingly, these perovskites experience the crystalline phase transition depending on the temperature, where the intrinsic excitonic properties can be largely altered. Until now, investigations on fundamental excitonic properties with the phase transition are in the beginning stage, and thus it is important to understand the phase-dependent properties in order to realize efficient perovskite-based optoelectronic devices. In this work, we investigated the evolution of exciton diffusion length and exciton lifetime under the phase transition of CH3NH3PbBr3 single crystals using spatially resolved photoluminescence imaging and time-resolved spectroscopy. CH3NH3PbBr3 single crystals showed a clear phase dependence for the exciton diffusion coefficient from cubic, through tetragonal, to orthorhombic phases. These findings would provide insights into the phase-dependent exciton properties of lead halide perovskites.
References
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[2] Q. Dong, Y. Fang, Y. Shao, P. Mulligan, J. Qiu, L. Cao, and J. Huang, Science, 347, 967‒970 (2015).
[3] L. Protesescu, S. Yakunin, M. I. Bodnarchuk, F. Krieg, R. Caputo, C. H. Hendon, R. X. Yang, A. Walsh, and M. V. Kovalenko, Nano Letters, 15, 3692‒3696 (2015).
