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.
Bibliographical noteFunding Information:
This research was supported by Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (2018M3D1A1058536). Computational resources have been provided by the KISTI Supercomputing Center (KSC-2018-CRE-0108). We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1).
© 2021 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry