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Effect of Anisotropic Confinement on Electronic Structure and Dynamics of Band Edge Excitons in Inorganic Perovskite Nanowires
journal contribution
posted on 2020-02-24, 20:45 authored by Brendan
D. Folie, Jenna A. Tan, Jianmei Huang, Peter C. Sercel, Milan Delor, Minliang Lai, John L. Lyons, Noam Bernstein, Alexander L. Efros, Peidong Yang, Naomi S. GinsbergInorganic
lead halide perovskite nanostructures show promise as
the active layers in photovoltaics, light emitting diodes, and other
optoelectronic devices. They are robust in the presence of oxygen
and water, and the electronic structure and dynamics of these nanostructures
can be tuned through quantum confinement. Here we create aligned bundles
of CsPbBr3 nanowires with widths resulting in quantum confinement
of the electronic wave functions and subject them to ultrafast microscopy.
We directly image rapid one-dimensional exciton diffusion along the
nanowires, and we measure an exciton trap density of roughly one per
nanowire. Using transient absorption microscopy, we observe a polarization-dependent
splitting of the band edge exciton line, and from the polarized fluorescence
of nanowires in solution, we determine that the exciton transition
dipole moments are anisotropic in strength. Our observations are consistent
with a model in which splitting is driven by shape anisotropy in conjunction
with long-range exchange.