Formation of Long-Lived Color Centers for Broadband Visible Light Emission in Low-Dimensional Layered Perovskites.
Journal of the American Chemical Society
American Chemical Society
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Booker, E., Thomas, T., Quarti, C., Stanton, M., Dashwood, C. D., Gillett, A., Richter, J., et al. (2017). Formation of Long-Lived Color Centers for Broadband Visible Light Emission in Low-Dimensional Layered Perovskites.. Journal of the American Chemical Society, 139 (51), 18632-18639. https://doi.org/10.1021/jacs.7b10223
We investigate the origin of the broadband visible emission in layered hybrid lead-halide perovskites and its connection with structural and photophysical properties. We study <001> oriented thin films of hexylammonium (HA) lead iodide, (C6H16N)2PbI4, and dodecylammonium (DA) lead iodide, (C12H28N)2PbI4 by combining first-principles simulations with time-resolved photoluminescence, steady-state absorption and X-ray diffraction measurements on cooling from 300 K to 4 K. Ultrafast transient absorption and photoluminescence measurements are used to track the formation and recombination of emissive states. In addition to the excitonic photoluminescence near the absorption edge, we find a red-shifted, broadband (full-width at half maximum of about 0.4 eV), emission band below 200 K, similar to emission from <110> oriented bromide 2D perovskites at room temperature. The lifetime of this sub-bandgap emission exceeds that of the excitonic transition by orders of magnitude. We use X-ray diffraction measurements to study the changes in crystal lattice with temperature. We report changes in the octahedral tilt and lattice spacing in both materials, together with a phase change around 200 K in DA2PbI4. DFT simulations of the HA2PbI4 crystal structure indicate that the low-energy emission is due to interstitial iodide and related Frenkel defects. Our results demonstrate that white-light emission is not limited to <110> oriented bromide 2D perovskites but a general property of this class of system and highlight the importance of defect control for the formation of low-energy emissive sites, which can provide a pathway to design tailored white-light emitters.
EPSRC (via University of Liverpool) (unknown)
UNIVERSITY OF LIVERPOOL (FB EPSRC) (EP/L01551X/1)
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External DOI: https://doi.org/10.1021/jacs.7b10223
This record's URL: https://www.repository.cam.ac.uk/handle/1810/271757
Attribution 4.0 International
Licence URL: http://creativecommons.org/licenses/by/4.0/
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