CdTe魔尺寸纳米晶的合成及其生长机理研究

CdTe魔尺寸纳米晶的合成及其生长机理研究

王坤，刘明洋，余启钰*，余睽

（四川大学原子与分子物理研究所，四川成都 610065）

摘要：不同于半导体常规纳米晶（RNCs），魔尺寸纳米晶（MSNCs）由于其精确的结构以及超窄的带边

荧光发射引起了人们广泛的关注。然而MSNCs的合成常为不同种类的MSNCs和RNCs的掺杂混合，这使

得高纯度、单一尺寸的MSNCs的合成往往十分困难。本文以醋酸镉和三辛基碲化膦为镉前驱体和碲前驱

体，长链烷基酸为表面配体，利用高温热注的方法在1-十八烯中成功合成了两种单一尺寸的CdTe MSNCs。

实验结果表明，适当链长的配体酸以及相对较低的酸量是抑制RNCs生长，合成单一尺寸的CdTe MSNCs

的关键。反应温度则很大程度上决定了生成的MSNCs的尺寸。采用TEM、EDX、XPS和XRD分析了所

合成的CdTe MSNCs的形貌、组成以及结构，结果显示其呈现为均一的点状形貌、且具有富镉的纤锌矿型

结构。通过对升温处理过程中CdTe MSNCs所呈现出来的非连续生长模式进一步分析，提出了一种类似

Ostwald ripening的生长机制，即部分的CdTe MSNCs在高温下直接分解成单体，沉积在另一部分CdTe

MSNCs上，使其“跳跃式”的生长成了尺寸更大的MSNCs。

关键词：碲化镉; 魔尺寸纳米晶; 高纯度; 生长机理; 有机酸

中图分类号：O611.4文献标志码：A

The Study of CdTe Magic-Size Nanocrystal Synthesis and Growth Mechanism

Kun Wang, Mingyang Liu, Qiyu Yu, Kui Yu

(Institute of Atomic and Molecular Physics ,Sichuan Univ. ,Chengdu 610065 ,China)

Abstract: Magic-size nanocrystals (MSNCs) have recently attracted much attention because they are more stable compared to their similar-sized counterparts called regular nanocrystals (RNCs) due to their defined molecular structures. However, the synthesis of MSNCs in pure form has been acknowledged to be challenging since the coexistence of different types of MSNCs and RNCs is difficult to avoid. In the present study, CdTe MSNCs were prepared from cadmium-acetate / carboxylic acid and tri-n-octylphosphine telluride in non-coordinating solvent 1-octadecene. It was generally found that only with small amounts of carboxylic acid it is possible to obtain MSNCs of high purity. Furthermore, two different types of CdTe MSNCs were synthesized by simply varying the reaction temperature. TEM, HRTEM, XRD, EDX and XPS were used to examine the morphology, composition and crystal structure of the as-prepared CdTe MSNCs which exhibit a dot-like morphology, a wurtzite structure and a Cd-rich surface composition. Additional experiments were performed to study the growth mechanism of MSNCs using UV-vis absorption real-time monitoring. Our results suggest that larger MSNCs growh at the expense of smaller ones partly dissolving into monomer which serve as growth material similar to Ostwald ripening commonly observed for RNCs.

Key Words: CdTe; magic-size nanocrystals; high-purity; growth mechanism; carboxylic acid

半导体魔尺寸纳米晶（magic-size nanocrystals，MSNCs）是一类特殊的量子点，近年来引起了广泛的关注[1-4]。它们具有特定原子数目组成的稳定结构，根据所含原子数的不同，可以形成一系列非连续尺寸的MSNCs。相比常规纳米晶（regular nanocrystals，RNCs），MSNCs可以合成得到尺寸绝对均一的样品，从而呈现出比RNCs更加优异的光学性质。目前对RNCs的认识已经比较成熟，但对MSNCs的结构、组成、形貌等的认识非常有限[5]，且充满争议[6]。另外，MSNCs的生长规律与RNCs 也有很大的差别[7]，在合成过程中如何控制MSNCs 的生长同时抑制RNCs的形成，从而得到单一尺寸

收稿日期：

基金项目:国家自然科学基金(21573155)

作者简介：王坤（1991—），男，硕士.研究方向:量子点材料

*通信联系人:E-mail:yuqiyu@

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