期刊
ACS NANO
卷 12, 期 10, 页码 10178-10188出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b05092
关键词
perovskite; nanocrystal; exciton; optical gain; broadband pump-probe spectroscopy
类别
资金
- FWO-Vlaanderen
- European Commission via the Marie-Sklodowska Curie action Phonsi [H2020-MSCA-ITN-642656]
- Research Foundation Flanders [17006602]
- Ghent University (GOA) [01G01513]
- Marsden Fund
Following the introduction of perovskites for photovoltaic solar energy conversion, the use of these materials as a general purpose optoelectronic material for displays, lighting, and lasing has been explored. However, while reports on stimulated emission and lasing by perovskites show great promise, a comprehensive quantification of their optical gain characteristics is lacking. Here, we measure gain coefficients, clarify the gain mechanism, and explore the gain dynamics of colloidal CsPbBr3 nanocrystals by deploying a unique combination of broadband transient absorption and ultrafast fluorescence spectroscopy. Opposite from current literature, we show that optical gain in such nanocrystals is supported by stimulated emission from free carriers, and not from excitons or biexcitons. Importantly, we demonstrate that the concomitant gain coefficients and thresholds agree with literature results reported for perovksite thin films. Finally, we show that, even in the case of fully inorganic lead halide perovskites, a cooling bottleneck hampers the development of net stimulated emission at high excitation density. Based on these results, we propose that bulk-like colloidal nanocrystals in general offer a unique testbed to quantify optical gain of novel photonic materials and in particular for lead halide perovskites.
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