Luo Chao, Li Wen, Xiong Da, Fu Ji, Yang Weiqing
Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, PR China.
Nanoscale. 2019 Aug 15;11(32):15206-15215. doi: 10.1039/c9nr05217h.
The photoluminescence quantum yields (PLQYs) of all-inorganic halide perovskites in the green and red spectral ranges have approached over 90%, overwhelmingly arousing burgeoning interests for creating a revolution in next-generation high-definition displays. However, obtaining pure blue-emitting perovskites with high PLQYs still remains a challenge. Herein, we designed a novel strategy to pre-optimize CsPbCl3 quantum dots (QDs) using praseodymium(iii) chloride (PrCl3), and then efficient blue-emitting CsPbBrxCl3-x QDs were obtained through halide exchange between the optimized CsPbCl3 and efficient CsPbBr3 QDs. Specifically, the PrCl3 optimization simultaneously and efficiently passivated the surface vacancy defects and appropriately reduced the surface long-chain organic ligands of the CsPbCl3 QDs, synergistically eliminating the deep trap states, and hence considerably suppressing nonradiative recombination. As a result, the radiative recombination rate was enhanced by more than one order of magnitude from 4.3 to 79 μs-1. Benefiting from this, the blue-emitting CsPbBrxCl3-x QDs exhibited an admirable PLQY of up to 89%, which is competitive compared with that of the state-of-the-art red and green-emitting perovskites. This strategy provides a unique understanding regarding the low PLQY of blue-emitting perovskites and an efficient method to boost it, which is especially attractive for constructing efficient blue and white light-emitting diodes.
全无机卤化物钙钛矿在绿色和红色光谱范围内的光致发光量子产率（PLQYs）已接近90%以上，极大地激发了人们对在下一代高清显示器领域引发一场革命的新兴兴趣。然而，获得具有高PLQYs的纯蓝色发光钙钛矿仍然是一个挑战。在此，我们设计了一种新颖的策略，使用氯化镨（PrCl3）对CsPbCl3量子点（QDs）进行预优化，然后通过优化后的CsPbCl3与高效的CsPbBr3量子点之间的卤化物交换，获得了高效的蓝色发光CsPbBrxCl3-x量子点。具体而言，PrCl3优化同时有效地钝化了表面空位缺陷，并适当减少了CsPbCl3量子点的表面长链有机配体，协同消除了深陷阱态，从而显著抑制了非辐射复合。结果，辐射复合率从4.3 μs-1提高到79 μs-1以上，提高了一个多数量级。受益于此，蓝色发光的CsPbBrxCl3-x量子点表现出高达89%的令人钦佩的PLQY，与最先进的红色和绿色发光钙钛矿相比具有竞争力。该策略为理解蓝色发光钙钛矿的低PLQY提供了独特的视角，并提供了一种提高其PLQY的有效方法，这对于构建高效的蓝色和白色发光二极管尤其具有吸引力。
