TY - JOUR
T1 - Directional Negative Thermal Expansion and Large Poisson Ratio in CH3NH3PbI3 Perovskite Revealed by Strong Coherent Shear Phonon Generation
AU - Mante, Pierre Adrien
AU - Stoumpos, Constantinos C.
AU - Kanatzidis, Mercouri G.
AU - Yartsev, Arkady
N1 - Funding Information:
The work at Lund University was supported by the Crafoord Foundation, the Knut and Alice Wallenberg Foundation, and Grant 2017-05150 from the Swedish Research Council (VR). The work at Northwestern University was supported by Grant SC0012541 from the U.S. Department of Energy, Office of Science.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/6/21
Y1 - 2018/6/21
N2 - Despite the enormous amount of attention CH3NH3PbI3 has received, we are still lacking an in-depth understanding of its basic properties. In particular, the directional mechanical and structural characteristics of this material have remained elusive. Here, we investigate these properties by monitoring the propagation of longitudinal and shear phonons following the absorption of a femtosecond pulse along various crystalline directions of a CH3NH3PbI3 single crystal. We first extract the sound velocities of longitudinal and transverse phonons along these directions of the crystal. Our study then reveals the negative directional thermal expansion of CH3NH3PbI3, which is responsible for strong coherent shear phonon generation. Finally, from these observations, we perform elastic characterization of this material, revealing a large directional Poisson's ratio, which reaches 0.7 and that we associate with the weak mechanical stability of this material. Our results also provide guidelines to fabricate a transducer of high-frequency transverse phonons.
AB - Despite the enormous amount of attention CH3NH3PbI3 has received, we are still lacking an in-depth understanding of its basic properties. In particular, the directional mechanical and structural characteristics of this material have remained elusive. Here, we investigate these properties by monitoring the propagation of longitudinal and shear phonons following the absorption of a femtosecond pulse along various crystalline directions of a CH3NH3PbI3 single crystal. We first extract the sound velocities of longitudinal and transverse phonons along these directions of the crystal. Our study then reveals the negative directional thermal expansion of CH3NH3PbI3, which is responsible for strong coherent shear phonon generation. Finally, from these observations, we perform elastic characterization of this material, revealing a large directional Poisson's ratio, which reaches 0.7 and that we associate with the weak mechanical stability of this material. Our results also provide guidelines to fabricate a transducer of high-frequency transverse phonons.
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U2 - 10.1021/acs.jpclett.8b01330
DO - 10.1021/acs.jpclett.8b01330
M3 - Article
C2 - 29806455
AN - SCOPUS:85047721021
VL - 9
SP - 3161
EP - 3166
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
SN - 1948-7185
IS - 12
ER -