Composition-Dependent Energy Splitting between Bright and Dark Excitons in Lead Halide Perovskite Nanocrystals
- 21 February 2018
- journal article
- research article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 18 (3), 2074-2080
- https://doi.org/10.1021/acs.nanolett.8b00184
Abstract
Perovskite semiconductor nanocrystals with different compositions have shown promise for applications in light-emitting devices. Dark excitonic states may suppress light emission from such nanocrystals by providing an additional non-radiative recombination channel. Here, we study the composition dependence of dark exciton dynamics in nanocrystals of lead halides by time-resolved photoluminescence spectroscopy at cryogenic temperatures. The presence of spin-related dark states is revealed by magneto-optical spectroscopy. The energy splitting between bright and dark states is found to be highly sensitive to both halide elements and organic cations, which is explained by considering the effects of size confinement and charge screening, respectively, on the exchange interaction. These findings suggest the possibility of manipulating dark exciton dynamics in perovskite semiconductor nanocrystals by composition engineering which will be instrumental in the design of highly efficient light-emitting devices.Keywords
Funding Information
- Ministry of Science and Technology of the People's Republic of China (2017YFA0303700, 2013CB932903)
- Natural Science Foundation of Jiangsu Province (BK20160019)
- National Natural Science Foundation of China (11574140, 11621091, 91233103)
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