Zhou Shu
School of Materials, Sun Yat-sen University Guangzhou 510275 China
Department of Physics, The Chinese University of Hong Kong New Territories Hong Kong.
RSC Adv. 2021 Aug 23;11(45):28410-28419. doi: 10.1039/d1ra04578d. eCollection 2021 Aug 16.
We report the rapid separation and purification of lead halide perovskite quantum dots (QDs) in a nonpolar solvent by using a convenient and efficient differential separation method. Size-selective precipitation effectively separates the perovskite QDs from larger aggregates and provides direct evidence for strong quantum confinement in the photoluminescence (PL). Significantly, the size-selected perovskite QDs are readily well-dispersed in a nonpolar solvent and remain stable in ambient air (humidity > 60%) for >20 days. These enable measurement of the electronic band structure of versatile perovskite QDs as a function of size for the first time. Despite a clear blue-shift of the optical bandgap, the lowest unoccupied molecular orbital (LUMO) readily moves towards the vacuum level while the highest occupied molecular orbital (HOMO) changes slightly, in good agreement with that observed in the quantum size effect tuning of quasi-2D perovskites and colloidal semiconductor QDs. The results demonstrate the possibility of utilizing differential centrifugation as a novel method to attain size-dependent tunability for property-specific perovskite-QD based optoelectronic applications.
我们报道了通过一种简便高效的差速分离方法，在非极性溶剂中快速分离和纯化卤化铅钙钛矿量子点（QDs）。尺寸选择性沉淀有效地将钙钛矿量子点与较大的聚集体分离，并为光致发光（PL）中的强量子限域提供了直接证据。值得注意的是，尺寸选择的钙钛矿量子点很容易在非极性溶剂中良好分散，并且在环境空气中（湿度>60%）保持稳定超过20天。这些首次使得能够测量通用钙钛矿量子点的电子能带结构作为尺寸的函数。尽管光学带隙明显蓝移，但最低未占据分子轨道（LUMO）很容易向真空能级移动，而最高占据分子轨道（HOMO）变化不大，这与在准二维钙钛矿和胶体半导体量子点的量子尺寸效应调谐中观察到的情况非常一致。结果表明，利用差速离心作为一种新方法来实现基于钙钛矿量子点的特定性质光电器件的尺寸依赖性可调谐性是可能的。
