3 research outputs found
Ultrafast Imaging of Carrier Cooling in Metal Halide Perovskite Thin Films
Understanding carrier
relaxation in lead halide perovskites at
the nanoscale is critical for advancing their device physics. Here,
we directly image carrier cooling in polycrystalline CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> films with nanometer spatial resolution.
We observe that upon photon absorption, highly energetic carriers
rapidly thermalize with the lattice at different rates across the
film. The initial carrier temperatures vary by many multiples of the
lattice temperature across hundreds of nanometers, a factor that cannot
be accounted for by excess photon energy above the bandgap alone or
in variations of the initial carrier density. Electron microscopy
suggests that morphology plays a critical role in determining the
initial carrier temperature and that carriers in small crystal domains
decay slower than those in large crystal domains. Our results demonstrate
that local disorder dominates the observed carrier behavior, highlighting
the importance of making local rather than averaged measurements in
these materials
Ultrafast Imaging of Carrier Cooling in Metal Halide Perovskite Thin Films
Understanding carrier
relaxation in lead halide perovskites at
the nanoscale is critical for advancing their device physics. Here,
we directly image carrier cooling in polycrystalline CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> films with nanometer spatial resolution.
We observe that upon photon absorption, highly energetic carriers
rapidly thermalize with the lattice at different rates across the
film. The initial carrier temperatures vary by many multiples of the
lattice temperature across hundreds of nanometers, a factor that cannot
be accounted for by excess photon energy above the bandgap alone or
in variations of the initial carrier density. Electron microscopy
suggests that morphology plays a critical role in determining the
initial carrier temperature and that carriers in small crystal domains
decay slower than those in large crystal domains. Our results demonstrate
that local disorder dominates the observed carrier behavior, highlighting
the importance of making local rather than averaged measurements in
these materials
Ultrafast Imaging of Carrier Cooling in Metal Halide Perovskite Thin Films
Understanding carrier
relaxation in lead halide perovskites at
the nanoscale is critical for advancing their device physics. Here,
we directly image carrier cooling in polycrystalline CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> films with nanometer spatial resolution.
We observe that upon photon absorption, highly energetic carriers
rapidly thermalize with the lattice at different rates across the
film. The initial carrier temperatures vary by many multiples of the
lattice temperature across hundreds of nanometers, a factor that cannot
be accounted for by excess photon energy above the bandgap alone or
in variations of the initial carrier density. Electron microscopy
suggests that morphology plays a critical role in determining the
initial carrier temperature and that carriers in small crystal domains
decay slower than those in large crystal domains. Our results demonstrate
that local disorder dominates the observed carrier behavior, highlighting
the importance of making local rather than averaged measurements in
these materials