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. 2022 May 31;15(9):8564–8572. doi: 10.1007/s12274-022-4421-4

Size matters: Steric hindrance of precursor molecules controlling the evolution of CdSe magic-size clusters and quantum dots

Juan Shen 1, Chaoran Luan 2,✉, Nelson Rowell 3, Yang Li 4, Meng Zhang 1, Xiaoqin Chen 4, Kui Yu 1,2,4,✉
PMCID: PMC9154029  PMID: 35669506

Abstract

Little is known about how to precisely promote the selective production of either colloidal semiconductor metal chalcogenide (ME), magic-size clusters (MSCs), or quantum dots (QDs). Recently, a two-pathway model has been proposed to comprehend their evolution; here, we reveal for the first time that the size of precursors plays a decisive role in the selected evolution pathway of MSCs and QDs. With the reaction of cadmium myristate (Cd(MA)2) and tri-n-octylphosphine selenide (SeTOP) in 1-octadecene (ODE) as a model system, the size of Cd precursors was manipulated by the steric hindrance of carboxylic acid (RCOOH) additive. Without RCOOH, the reaction produced both CdSe MSCs and QDs (from 100 to 240 °C). With RCOOH, the reaction produced MSCs or QDs when R was small (such as CH3−) or large (such as C6H5−), respectively. According to the two-pathway model, the selective evolution is attributed to the promotion and suppression of the self-assembly of Cd and Se precursors, respectively. We propose that the addition of carboxylic acid may occur ligand exchange with Cd(MA)2, causing the different sizes of Cd precursor. The results suggest that the size of Cd precursors regulates the self-assemble behavior of the precursors, which dictates the directed evolution of either MSCs or QDs. The present findings bring insights into the two-pathway model, as the size of M and E precursors determine the evolution pathways of MSCs or QDs, the understanding of which is of great fundamental significance toward mechanism-enabled design and predictive synthesis of functional nanomaterials.

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Electronic Supplementary Material

Supplementary material (additional optical absorption spectra, TEM, NMR, FT-IR, and XRD) is available in the online version of this article at 10.1007/s12274-022-4421-4.

Keywords: cadmium selenide (CdSe), magic-size clusters (MSCs), quantum dots (QDs), self-assembly, steric hindrance

Electronic Supplementary Material

12274_2022_4421_MOESM1_ESM.pdf (1.7MB, pdf)

Size matters: Steric hindrance of precursor molecules controlling the evolution of CdSe magic-size clusters and quantum dots

Acknowledgements

K. Y. thanks the National Natural Science Foundation of China (NSFC, No. 21773162), the Fundamental Research Funds for the Central Universities, the Applied Basic Research Programs of Science and Technology Department of Sichuan Province (No, 2020YJ0326), the State Key Laboratory of Polymer Materials Engineering of Sichuan University respectively for No. sklpme2020-2-09, and the Open Project of Key State Laboratory for Supramolecular Structures and Materials of Jilin University for No. SKLSSM 2021030. M. Z. is grateful to National Natural Science Foundation of China ((NSFC, No. 22002099), China Postdoctoral Science Foundation (No. 2020T130441), Sichuan University postdoctoral interdisciplinary Innovation Fund and the Open Project of Key State Laboratory for Supramolecular Structures and Materials of Jilin University (No. SKLSSM 2021032). C. R. L. is grateful to the COVID-19 Science and Technology Emergency Project of Sichuan Province of China (No. 2021YFS0408). We thank the Analytical & Testing Center of Sichuan University for TEM.

Contributor Information

Chaoran Luan, Email: luanc@scu.edu.cn.

Kui Yu, Email: kuiyu@scu.edu.cn.

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12274_2022_4421_MOESM1_ESM.pdf (1.7MB, pdf)

Size matters: Steric hindrance of precursor molecules controlling the evolution of CdSe magic-size clusters and quantum dots

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