Sauvage Center for Molecular Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan430072, P. R. China.
College of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan430023, P. R. China.
Inorg Chem. 2023 Feb 13;62(6):2877-2886. doi: 10.1021/acs.inorgchem.2c04308. Epub 2023 Feb 1.
InP quantum dots (QDs) attract growing interest in recent years, owing to their environmental advantages upon applications in display and lighting. However, compared to Cd-based QDs and Pb-based perovskites, the synthesis of InP QDs with high optical quality is relatively more difficult. Here, we established a mid-synthetic modification approach to improve the optical properties of InP-based QDs. Tris(dimethylamino)phosphine ((DMA)P) and indium iodide were used to prepare InP QDs with a green emission (∼527 nm). By introducing zinc halides (ZnX) during the mid-synthetic process, the photoluminescence quantum yield (PLQY) of the resulting InP/ZnSeS/ZnS core/shell/shell QDs was increased to >70%, and the full-width-at-half-maximum (FWHM) could be narrowed to ∼40 nm. Transmission electron microscopy clearly showed the improvement of the QDs particle size distribution after introducing ZnX. It was speculated that ZnX was bound to the surface of QDs as a Z-type ligand, which not only passivated surface defects and suppressed the emission of defect states but also prevented Ostwald ripening. The InP cores were also activated by ZnX, which made the growth of the ZnSeS shell more favorable. The photoluminescence properties started to be improved significantly only when the amount of ZnX exceeded 0.5 mmol. As the amount increased, more ZnX was distributed around the QDs to form a ligand layer, which prevented the shell precursor from crossing the ligand layer to the surface of the InP core, thus reducing the size of the InP/ZnSeS/ZnS QDs. This work revealed a new role of ZnX and found a method for InP QDs with high brightness and low FWHM by the mid-synthetic modification, which would inspire the synthesis of even better InP QDs.
铟磷量子点（InP QDs）由于在显示和照明应用方面具有环境优势，近年来引起了越来越多的关注。然而，与基于 Cd 的 QDs 和基于 Pb 的钙钛矿相比，合成具有高光学质量的 InP QDs 相对更为困难。在这里，我们建立了一种中合成修饰方法来改善基于 InP 的 QDs 的光学性能。三（二甲氨基）膦（(DMA)P）和碘化铟用于制备发绿光（∼527nm）的 InP QDs。通过在中合成过程中引入卤化锌（ZnX），所得 InP/ZnSeS/ZnS 核/壳/壳 QDs 的光致发光量子产率（PLQY）提高到＞70%，半峰全宽（FWHM）可窄至～40nm。透射电子显微镜清楚地显示了引入 ZnX 后 QDs 粒径分布的改善。据推测，ZnX 作为 Z 型配体结合到 QDs 的表面，不仅可以钝化表面缺陷并抑制缺陷态的发射，还可以防止奥斯特瓦尔德熟化。ZnX 还激活了 InP 核，使 ZnSeS 壳的生长更加有利。只有当 ZnX 的量超过 0.5mmol 时，光致发光性能才开始显著提高。随着 ZnX 用量的增加，更多的 ZnX 分布在 QDs 周围形成配体层，阻止壳前体穿过配体层到达 InP 核的表面，从而减小了 InP/ZnSeS/ZnS QDs 的尺寸。这项工作揭示了 ZnX 的新作用，并通过中合成修饰找到了一种制备高亮度、低 FWHM 的 InP QDs 的方法，这将激发更好的 InP QDs 的合成。
