The metal halide Cs3Cu2I5 displays anomalous optical properties: an optical absorption onset in the ultraviolet region (∼330 nm) with highly efficient luminescence in the blue region (∼445 nm). Although self-trapped exciton formation has been proposed as the origin of giant Stokes shift, its connection to the photoluminescence quantum yield exceeding 90% remains unknown. Here, we explore the photochemistry of Cs3Cu2I5 from first-principles and reveal a low energy barrier for exciton self-trapping associated with Cu-Cu dimerization. Kinetic analysis shows that the quantum yield of blue emission in Cs3Cu2I5 is sensitive to the excited carrier density due to the competition between exciton self-trapping and band-to-band radiative recombination.
|Number of pages||6|
|Journal||Journal of Physical Chemistry Letters|
|State||Published - 2 Sep 2021|