Dynamic
Optical Properties of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Single
Crystals As Revealed by One- and Two-Photon
Excited Photoluminescence Measurements
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Abstract
The dynamic optical properties of
perovskite CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> single crystals
were studied by means of time-resolved
photoluminescence (PL) spectroscopy at room temperature. The PL peak
under one-photon excitation exhibits a red-shift with elapsing time,
while two-photon PL is time-independent and appears at lower energy
levels. The low-energy two-photon PL can be attributed to emissions
from the localized states because of strong band-to-band absorption
and photon re-absorption of the emitted light in the interior region.
We revealed that the PL behaviors can be explained by the diffusion
of photocarriers generated in the near-surface region to the interior
region. The excitation fluence dependence of the one-photon PL dynamics
is also discussed in terms of the electron–hole radiative recombination
and carrier diffusion effects