State Key Laboratory of Luminescent Materials and Devices, and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques , South China University of Technology , Guangzhou 510641 , China.
ACS Appl Mater Interfaces. 2019 Dec 18;11(50):47227-47236. doi: 10.1021/acsami.9b15990. Epub 2019 Dec 6.
Cesium lead halide (CsPbX, X = Cl, Br, I) perovskite quantum dots (QDs) have been intriguing optoelectronic materials for applications in various devices owing to their superior electronic and optical properties. However, poor resistance to humidity and light irradiation impedes their promotion. Herein, bulk perovskite-type layered CsCaTaO is exfoliated into two-dimensional (2D) negatively charged CaTaO (CTO) nanosheets as seeds to in situ synthesize and composite CsPbBr. The as-synthesized CsPbBr/CTO nanocomposites possess improved green emission with apparently prolonged decay time with reference to bare CsPbBr QDs. The decay time can retrieve to a normal state when the nanocomposites are treated with some water. It is found that the CTO acts as a defect to trap the bound exciton of the loaded CsPbBr. Protons from water can preferably replace Cs at the interface of the nanocomposites, resulting in the separation of the nanosheets and CsPbBr and retrieving the decay time. X-ray photoelectron spectroscopy results also indicate the strong interaction between CsPbBr and CTO with reference to the physical mixing sample of bare CsPbBr QDs and CTO nanosheets. The decoration of ultrathin 2D charge-bearing oxide nanosheets on the QDs benefits significant improvements in humidity resistance and photostability performance in light-emitting diode devices. This research offers a distinct strategy to modify the surface of perovskite QDs.
铯铅卤（CsPbX，X=Cl、Br、I）钙钛矿量子点（QDs）因其优异的电子和光学性能，在各种器件中的应用引起了人们的兴趣。然而，对湿度和光辐照的抵抗力差阻碍了它们的推广。在此，体相钙钛矿型层状 CsCaTaO 被剥离成二维（2D）带负电荷的 CaTaO（CTO）纳米片作为种子，原位合成并复合 CsPbBr。与纯 CsPbBr QDs 相比，所合成的 CsPbBr/CTO 纳米复合材料具有改善的绿光发射，明显延长的衰减时间。当纳米复合材料用一些水进行处理时，衰减时间可以恢复到正常状态。研究发现，CTO 作为一个缺陷，可以捕获负载的 CsPbBr 的束缚激子。来自水的质子可以优先取代纳米复合材料界面处的 Cs，导致纳米片和 CsPbBr 的分离，并恢复衰减时间。X 射线光电子能谱结果也表明，与纯 CsPbBr QDs 和 CTO 纳米片的物理混合样品相比，CsPbBr 和 CTO 之间存在强烈的相互作用。在 QDs 上装饰超薄 2D 带电氧化物纳米片，有利于显著提高发光二极管器件的抗湿性和光稳定性性能。这项研究为修饰钙钛矿 QDs 的表面提供了一种独特的策略。
