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One Stone, Two Birds: High-Efficiency Blue-Emitting Perovskite Nanocrystals for LED and Security Ink Applications

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journal contribution
posted on 20.06.2019 by Chun Sun, Zhiyuan Gao, Hanxin Liu, Le Wang, Yuchen Deng, Peng Li, Huanrong Li, Zi-Hui Zhang, Chao Fan, Wengang Bi
Blue-emitting perovskite nanocrystals (NCs) are known to exhibit low photoluminescence (PL) quantum yield (QY) compared to green- and red-emitting counterparts, which is due to the presence of localized trap states on the surface. Here, we demonstrate a new method to synthesize high-efficiency blue-emitting perovskite NCs by anion exchange of 0D and 3D perovskite NCs. The remarkable enhancement of the PL QY is caused by surface reconstruction and subsequent suppression of nonradiative recombination centers of 3D perovskite NCs during the anion exchange. Remarkably, these high-efficiency NCs have two appealing applications. First, they can be applied in backlight display, where the GaN light-emitting diode is usually used as the blue emission source. We found that the as-prepared NCs were facile to tune their emission peaks and possessed narrow linewidths. As a downconverter, the NCs realize an ultrapure blue light for backlight display. Second, benefiting from the existence of 0D perovskite, anticounterfeiting inks can also be achieved based on these blue-emitting perovskite NCs. The encoding/reading strategy relies on the conversion of 0D perovskites. These findings provide new opportunities for blue-emitting perovskite NCs and broaden their application.

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