铟合金化对厚壳InP/ZnSe量子点电荷载流子动力学的影响。

Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots.

作者信息

Freymeyer Nathaniel J, Click Sophia M, Reid Kemar R, Chisholm Matthew F, Bradsher Cara E, McBride James R, Rosenthal Sandra J

机构信息

Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.

Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.

出版信息

J Chem Phys. 2020 Apr 30;152(16):161104. doi: 10.1063/1.5145189.

DOI:10.1063/1.5145189

PMID:32357779

Abstract

Thick-shell InP/ZnSe III-V/II-VI quantum dots (QDs) were synthesized with two distinct interfaces between the InP core and ZnSe shell: alloy and core/shell. Despite sharing similar optical properties in the spectral domain, these two QD systems have differing amounts of indium incorporation in the shell as determined by high-resolution energy-dispersive x-ray spectroscopy scanning transmission electron microscopy. Ultrafast fluorescence upconversion spectroscopy was used to probe the charge carrier dynamics of these two systems and shows substantial charge carrier trapping in both systems that prevents radiative recombination and reduces the photoluminescence quantum yield. The alloy and core/shell QDs show slight differences in the extent of charge carrier localization with more extensive trapping observed in the alloy nanocrystals. Despite the ability to grow a thick shell, structural defects caused by III-V/II-VI charge carrier imbalances still need to be mitigated to further improve InP QDs.

摘要

厚壳InP/ZnSe III-V/II-VI量子点（QDs）是通过在InP核与ZnSe壳之间形成两种不同的界面合成的：合金界面和核/壳界面。尽管在光谱域中具有相似的光学性质，但通过高分辨率能量色散X射线光谱扫描透射电子显微镜测定，这两种量子点系统在壳层中的铟掺入量不同。超快荧光上转换光谱用于探测这两种系统的电荷载流子动力学，结果表明这两种系统中都存在大量的电荷载流子捕获现象，这阻止了辐射复合并降低了光致发光量子产率。合金量子点和核/壳量子点在电荷载流子局域化程度上存在细微差异，在合金纳米晶体中观察到更广泛的捕获现象。尽管能够生长厚壳，但由III-V/II-VI电荷载流子不平衡引起的结构缺陷仍需减轻，以进一步改善InP量子点。