Jan 26, 2021 |
Revealing the dynamic mechanism of lead-free quadruple perovskite nanocrystals
(Nanowerk News) In recent years, lead-free halide perovskite nanocrystals have drawn more and more attention due to their low toxicity, high stability and chemical diversity.
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It's important to reveal the carrier dynamics of lead-free perovskite nanocrystals to apply them effectively in the field of optoelectronic devices.
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A research group led by Prof. HAN Keli from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences revealed the luminescence enhancement mechanism of a series of new lead-free quadruple halide perovskite nanocrystals, and prepared high-performance photodetectors.
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This study was published in Advanced Materials ("Efficient Luminescent Halide Quadruple-Perovskite Nanocrystals via Trap-Engineering for Highly Sensitive Photodetectors").
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Efficient luminescent halide quadruple-perovskite nanocrystals via trap-engineering for highly sensitive photodetectors. (Image: YANG Bin and BAI Tianxin)
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The researchers reported for the first time a series of quadruple perovskite colloidal nanocrystals with ordered vacancies. By alloying Cs4MnBi2Cl12 nanocrystals, the fluorescence quantum yield could be increased by nearly 100 times.
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Through carrier ultrafast dynamics studies, the researchers found that in the quadruple perovskite nanocrystals, free excitons were rapidly self-trapped as "self-trapped excitons", and a self-trapped exciton-assisted donor-acceptor (Mn2+) occurred energy transfer process. Alloying could eliminate the ultra-fast defect state trapping process that competed with energy transfer, and increase the crystallinity of the nanocrystals, thereby improving the luminous efficiency. |
Based on the alloyed quadruple perovskite nanocrystals with high crystallinity and long carrier lifetime, the researchers prepared a photodetector, which had ultra-high responsivity. Its sensitivity was much higher than that of the previously reported photodetectors based on lead-free perovskite nanocrystals.
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The study shows that the quadruple perovskite type nanocrystal opens up new possibilities for photovoltaic applications.
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