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Boosting the Photoluminescence Efficiency of InAs Nanocrystals Synthesized with Aminoarsine via a ZnSe Thick-Shell Overgrowth
Advanced Materials ( IF 27.4 ) Pub Date : 2023-05-27 , DOI: 10.1002/adma.202303621
Dongxu Zhu 1 , Houman Bahmani Jalali 1, 2 , Gabriele Saleh 1 , Francesco Di Stasio 2 , Mirko Prato 3 , Nefeli Polykarpou 4 , Andreas Othonos 5 , Sotirios Christodoulou 4 , Yurii P Ivanov 6 , Giorgio Divitini 6 , Ivan Infante 7, 8 , Luca De Trizio 9 , Liberato Manna 1
Affiliation  

InAs-based nanocrystals can enable restriction of hazardous substances (RoHS) compliant optoelectronic devices, but their photoluminescence efficiency needs improvement. We report an optimized synthesis of InAs@ZnSe core@shell nanocrystals allowing to tune the ZnSe shell thickness up to seven mono-layers (ML) and to boost the emission, reaching a quantum yield of ≈70% at ≈900 nm. It is demonstrated that a high quantum yield can be attained when the shell thickness is at least ≈3ML. Notably, the photoluminescence lifetimeshows only a minor variation as a function of shell thickness, whereas the Auger recombination time (a limiting aspect in technological applications when fast) slows down from 11 to 38 ps when increasing the shell thickness from 1.5 to 7MLs. Chemical and structural analyses evidence that InAs@ZnSe nanocrystals do not exhibit any strain at the core-shell interface, likely due to the formation of an InZnSe interlayer. This is supported by atomistic modeling, which indicates the interlayer as being composed of In, Zn, Se and cation vacancies, alike to the In2ZnSe4 crystal structure. The simulations reveal an electronic structure consistent with that of type-I heterostructures, in which localized trap states can be passivated by a thick shell (>3ML) and excitons are confined in the core.

中文翻译:

通过 ZnSe 厚壳过度生长提高氨基胂合成 InAs 纳米晶体的光致发光效率

InAs基纳米晶体可以实现符合有害物质限制(RoHS)标准的光电器件,但其光致发光效率需要提高。我们报告了 InAs@ZnSe 核@壳纳米晶体的优化合成,可以将 ZnSe 壳厚度调整至七个单层 (ML) 并提高发射率,在 900 nm 处达到 70% 的量子产率。结果表明,当壳层厚度至少约为 3ML 时,可以获得高量子产率。值得注意的是,光致发光寿命随着壳厚度的变化仅表现出微小的变化,而当壳厚度从 1.5 增加到 7ML 时,俄歇复合时间(快速技术应用中的一个限制因素)从 11 ps 减慢到 38 ps。化学和结构分析表明,InAs@ZnSe 纳米晶体在核-壳界面处没有表现出任何应变,这可能是由于 In  Zn  Se夹层形成。这得到了原子模型的支持,原子模型表明中间层由In、Zn、Se和阳离子空位组成,类似于In 2 ZnSe 4晶体结构。模拟揭示了与 I 型异质结构一致的电子结构,其中局域陷阱态可以被厚壳 (>3ML) 钝化,并且激子被限制在核心中。
更新日期:2023-05-27
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