posted on 2020-06-24, 22:48authored byJeremy
T. Tisdale, Brianna Musicó, Bogdan Dryzhakov, Michael Koehler, David Mandrus, Veerle Keppens, Bin Hu
This
letter reports optomechanical effects occurring in a hybrid
metal-halide perovskite single crystal (MAPbBr3) based
on resonant ultrasound spectroscopy (RUS) measurements under continuous
wave (CW) laser illumination. The optomechanical effects are a new
phenomenon in hybrid perovskite single crystals where the elastic
constant of a single crystal is measured by RUS probed under varying
excitation conditions. Our studies show that applying a CW laser (405
nm) to the single-crystal face shifts the RUS peaks to higher frequencies
by about 1–4% in the perovskite single crystal at room temperature.
The light-induced shift of the RUS peaks can be observed only when
photoexcitation is occurring, rather than during heating, by positioning
the laser wavelength within the optical absorption spectrum. In contrast,
positioning the laser wavelength outside of the optical absorption
spectrum leads to an absence of RUS peak shifting. Clearly, the laser-light-induced
RUS peak shifts shows that the crystal elastic moduli can be changed
by photoexcitation, leading to an optomechanical phenomenon via excited
states. Essentially, the observed optomechanical phenomenon reflects
the fact that the mechanical properties can be optically changed through
internal repulsive and attractive force constants by external photoexcitation
in a hybrid perovskite single crystal.