Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photoinduced Vibrations Drive Ultrafast Structural Distortion in Lead
  Halide Perovskite   Organic-inorganic perovskites have shown great promise towards their
application in optoelectronics. The success of this class of material is
dictated by the complex interplay between various underlying microscopic
phenomena. The structural dynamics of organic cations and the inorganic
sublattice after photoexcitation is hypothesized to have a direct effect on the
material properties, thereby affecting the overall device performance. Here, we
use two-dimensional (2D) electronic spectroscopy to reveal impulsively excited
vibrational modes of methylammonium (MA) lead iodide perovskite, which drive
the structural distortion after photoexcitation. The vibrational analysis of
the measured data allows us to directly monitor the time evolution of the
librational motion of the MA cation along with the vibrational coherences of
inorganic sublattice. Wavelet analysis of the observed vibrational coherences
uncovers the interplay between these two types of phonons. It reveals the
coherent generation of the librational motion of the MA cation within ~300 fs,
which is complemented by the coherent evolution of the skeletal motion of the
inorganic sublattice. We have employed time-dependent density functional theory
(TDDFT) to study the atomic motion of the MA cation and the inorganic
sublattice during the process of photoexcitation. The TDDFT calculations
support our experimental observations of the coherent generation of librational
motions in the MA cation and highlight the importance of the anharmonic
interaction between the MA cation and the inorganic sublattice. Our
calculations predict the transfer of the photoinduced vibrational coherence
from the MA cation to the inorganic sublattice, which drives the skeleton
motion to form a polaronic state leading to long lifetimes of the charge
carriers. This work may lead to novel design principles for next generation of
solar cell materials.

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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: supr-con