Exceptional elastic anisotropy of hybrid organic–inorganic perovskite CH3NH3PbBr3 measured by laser ultrasonic technique |
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Authors: | Alexey M Lomonosov Xiaoliang Yan Chuanxiang Sheng Vitalyi E Gusev Chenyin Ni Zhonghua Shen |
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Institution: | 1. School of Science, Nanjing University of Science and Technology, Nanjing, P.R. China;2. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, Russia;3. School of Electronic Engineering and Optoelectronic Techniques, Nanjing University of Science and Technology, Nanjing, P.R. China;4. Laboratoire d'Acoustique de l'Université du Maine, Le Mans, France |
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Abstract: | The results of the direct experimental evaluation of all elastic constants of single crystal hybrid organic–inorganic perovskite (HOIP) methylammonium lead bromide, a material known due to its possible solar‐energy, optoelectronics, X‐ray detector and thermoelectricity applications, are reported. The measurements of anisotropic elasticity of CH3NH3PbBr3by the technique of laser ultrasonics demonstrate that properties of HOIPs can be even more remarkable than the theoretical expectations: the extracted shear modulus is more than twice smaller, the universal anisotropy is more than twice higher, while the Debye temperature is more than 50° lower. Thus HOIPs can exhibit extremely low shear rigidity and extremely high anisotropy, both strongly overrunning the parameters which have been expected based on earlier first principles theoretical predictions. A simple theoretical model of granular crystal indicates that these observations could be related to the contributions of rotations/tilts of PbBr6octahedra to elastic response of cubic CH3NH3PbBr3. Another experimental observation is strong stiffening of shear rigidity with temperature increase from its room value up to 120 °C. Discovered elastic properties of HOIPs characterize them as exceptionally ductile/flexible/adaptive materials which could be deposited on corrugated/structured surfaces. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) |
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Keywords: | hybrid materials perovskites laser ultrasonics elastic properties CH3NH3PbBr3 |
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