Graduate School of Organic Materials Science , Yamagata University , 4-3-16 Jonan , Yonezawa , Yamagata 992-8510 , Japan.
ACS Appl Mater Interfaces. 2018 Jul 25;10(29):24607-24612. doi: 10.1021/acsami.8b05954. Epub 2018 Jul 11.
Cesium lead halide (CsPbX, X = Cl, Br, or I) perovskite quantum dots (QDs) are known as ionic nanocrystals, and their optical properties are greatly affected by the washing solvent used during the purification process. Here, we demonstrate the purification process of CsPbBr perovskite QDs using low-dielectric-constant solvents to completely remove impurities, such as the reaction solvent and desorbed ligands. The use of the ether solvent diethylene glycol dimethyl ether (diglyme), having a low dielectric constant of ε = 7.23, as a poor solvent for reprecipitation allowed for multiple wash cycles, which led to high purity and high photoluminescence quantum yield for CsPbBr QDs. The light-emitting device constructed with the CsPbBr QDs and washed twice with diglyme (two-wash) showed a low turn-on voltage of 2.7 V and a peak external quantum efficiency of over 8%. Thus, the purification of perovskite QDs with multiple wash cycles using a low-dielectric-constant solvent is an effective approach for enhancing not only the optical properties but also the efficiency of perovskite quantum dot light-emitting devices.
铯铅卤（CsPbX，X = Cl、Br 或 I）钙钛矿量子点（QDs）被称为离子纳米晶体，其光学性质受纯化过程中使用的洗涤溶剂影响很大。在这里，我们展示了使用低介电常数溶剂来纯化 CsPbBr 钙钛矿 QDs 的过程，以完全去除杂质，例如反应溶剂和解吸配体。使用介电常数 ε = 7.23 的低醚溶剂二乙二醇二甲醚（diglyme）作为不良溶剂进行再沉淀，可以进行多次洗涤循环，从而得到高纯度和高光致发光量子产率的 CsPbBr QDs。用 diglyme 洗涤两次（两次洗涤）的 CsPbBr QDs 构建的发光器件的开启电压低至 2.7 V，外量子效率峰值超过 8%。因此，使用低介电常数溶剂进行多次洗涤循环来纯化钙钛矿 QDs 是一种有效方法，不仅可以提高光学性能，还可以提高钙钛矿量子点发光器件的效率。
