Ma Zhuang-Zhuang, Shi Zhi-Feng, Wang Lin-Tao, Zhang Fei, Wu Di, Yang Dong-Wen, Chen Xu, Zhang Yu, Shan Chong-Xin, Li Xin-Jian
Key Laboratory of Materials Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Daxue Road 75, Zhengzhou 450052, China.
State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012, China.
Nanoscale. 2020 Feb 14;12(6):3637-3645. doi: 10.1039/c9nr10075j. Epub 2020 Feb 4.
Recently, the discovery and development of lead-free perovskite quantum dots (QDs) that are eco-friendly and stable has become an active research area in low-cost lighting and display fields. However, the low photoluminescence quantum yield (PLQY) caused by the residual surface states of such QDs severely hinders their practical applications and commercialization. In this work, a strategy of employing water-induced nanocomposites was proposed to improve the PLQY of cesium bismuth halide (CsBiX) QDs, and a substantial enhancement by ∼130% (from 20.2% to 46.4%) was achieved by an optimized water treatment of CsBiBr QDs. A detailed analysis indicated that CsBiBr/BiOBr nanocomposites, in which the CsBiBr QD core was encapsulated into a BiOBr matrix, can effectively suppress the surface defects of QDs, resulting in a longer PL lifetime and a larger exciton binding energy compared with the pristine sample. Finally, the CsBiBr/BiOBr nanocomposites were used as the color-converting phosphors for down-conversion white light-emitting devices, which show a good operation stability in ambient air, significantly better than the reference device constructed with conventional lead-halide perovskites. We believe that the method used here provides an effective strategy to improve the fluorescence efficiency of lead-free perovskite QDs, which will create opportunities for their applications in lighting and displays.
近年来，发现并开发环保且稳定的无铅钙钛矿量子点（QDs）已成为低成本照明和显示领域的一个活跃研究方向。然而，此类量子点的残余表面态导致的低光致发光量子产率（PLQY）严重阻碍了它们的实际应用和商业化。在这项工作中，提出了一种采用水诱导纳米复合材料的策略来提高卤化铯铋（CsBiX）量子点的PLQY，通过对CsBiBr量子点进行优化的水处理，实现了约130%的显著提高（从20.2%提高到46.4%）。详细分析表明，CsBiBr/BiOBr纳米复合材料（其中CsBiBr量子点核心被封装在BiOBr基质中）能够有效抑制量子点的表面缺陷，与原始样品相比，其PL寿命更长，激子结合能更大。最后，CsBiBr/BiOBr纳米复合材料被用作下转换白光发光器件的颜色转换磷光体，在环境空气中显示出良好的运行稳定性，明显优于用传统卤化铅钙钛矿构建的参考器件。我们相信，这里使用的方法为提高无铅钙钛矿量子点的荧光效率提供了一种有效策略，这将为它们在照明和显示中的应用创造机会。
