Journal of Materials Chemistry C
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2020
·Vol. 9
·期 2
·555-561
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IF 7.059
Xiao Shao,Yue Wu,Shuang Jiang,Bin Li,Tianyong Zhang,Yong Yan
The chirality of inorganic semiconductor nanocrystals (NCs) was demonstrated to be sensitive to the particle structures and chiral molecules capped on the NC surfaces. In this work, we found the native achiral ligands used for the synthesis of NCs could also influence their circular dichroism (CD) response. With different native ‘growth’ ligands but similar semiconductor cores, the CD spectra of NCs exhibited mirror images by using the same enantiopure cysteine (Cys) ligands, indicating the inversion of NC chirality. In addition, distinct anisotropic dissymmetry factors (g-factor) were observed. With appropriate native ligands, we prepared chiral cysteine stabilized spherical CdSe NCs (quantum dots, QDs) with the highest g-factor ever reported.
研究领域:
材料科学
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化学
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DOI
高影响因子
Journal of the American Chemical Society
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2025
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IF 15.6
Xu Cao,Jiongzhao Li,Xudong Qian,Chuyue Li,Xiaogang Peng
Here, we demonstrate that monocrystalline (free of stacking faults) wurtzite CdSe nanocrystals with monodisperse size, shape (dots, rods, or wires), and facet structure are synthesized in both strongly confined and weakly confined size regimes. Considering the unique c-axis of wurtzite CdSe, we introduce a new type of neutral ligand (e.g., zinc-alkanoate ones) to pair with their dominating nonpolar low-index facets. Nucleation of the stacking fault-free wurtzite seeds instead of zinc-blende tetrahedrons is identified as the key step, which is optimized by a set of conditions matching the neutral zinc-alkanoate ligands. In the following growth stage, conditions are much less stringent, although the neutral zinc-alkanoate ligands are still critical in achieving nearly atomically flat facets of those monocrystalline nanocrystals. In the strongly confined size regime, the ensemble photoluminescence (PL) full-width-at-half-maximum (FWHM) of wurtzite CdSe nanocrystals reaches a record low (59 meV). In the weakly confined size regime, dual-peak PL caused by thermal population is observed. Monodisperse and monocrystalline wurtzite CdSe nanocrystals show distinctively size-dependent optical properties, in comparison with their zinc-blende counterparts. Results here suggest that the atomically precise synthesis of colloidal semiconductor nanocrystals is feasible, implying an advanced class of nanomaterials for exploring various optical and optoelectronic applications.
研究领域:
材料科学
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纳米技术
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光学
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产品关联
DOI
PubMed
高影响因子
LUMINESCENCE
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2014
·Vol. 29
·期 7
·818-823
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IF 1.675
Meiting Dong,Jingyi Xu,Shuxian Liu,Ying Zhou,Chaobiao Huang
Here we report a facile one-pot method for the preparation of high-quality CdSe nanocrystals (NCs) in aqueous solution under an air atmosphere. Compared with the traditional use of NaHSe or H 2 Se, the more stable sodium selenite is utilized as the Se source for preparing highly luminescent CdSe nanocrystals. By using mercaptosuccinic acid (MSA) as the capping agent and borate–citrate acid as the buffering solution, CdSe nanocrystals with high quantum yield (up to 70%) have been synthesized conveniently. The influence of different experimental parameters, such as the pH of the precursor solution, the molar ratio of Cd 2+ to Na 2 SeO 3 and Cd 2+ to MSA on the CdSe nanocrystals, has been systematically investigated. The prepared CdSe NCs were spherical with a size of ~ 5 nm. Copyright © 2014 John Wiley & Sons, Ltd.
研究领域:
材料科学
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化学
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产品关联
DOI
PubMed
高影响因子
CHINESE CHEMICAL LETTERS
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2019
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IF 3.839
Biwei Wang,Limin Liu,Yi Zhang,Yonghui Deng,Angang Dong
Highly luminescent colloidal nanocrystals have wide applications in bioimaging and various optoelectronic devices. Herein we report a facile and mild procedure by combining S 2− treatment and binary ligand passivation , which can efficiently enhance the luminescent property of CdSe nanocrystals at room temperature. The photoluminescence quantum yield of as-treated CdSe nanocrystals exhibits drastic enhancement ( e.g. , 188 times for CdSe nanorods) after this dual-passivation treatment. The methodology proposed here can be applied to various CdSe nanocrystals, regardless of their sizes, shapes, and crystal structures.
研究领域:
材料科学
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光学
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 110
·90570-90577
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IF 3.84
Limin Liu,Xianfeng Zhang,Li Ji,Hanwen Li,Huijuan Yu,Fangjie Xu,Jianhua Hu,Dong Yang,Angang Dong
In the surface treatment of colloidal nanocrystals (NCs), S2− ions have been widely employed as metal-free atomic ligands to efficiently replace the original long hydrocarbon ligands. Prior studies exclusively show that S2− ions considerably quench the photoluminescence (PL) of semiconductor NCs (e.g., CdSe and PbS) during ligand exchange. Here we report that the influence of S2− treatment on the luminescent properties of CdSe NCs is highly dependent on the NC size. We observe an unexpected PL brightening phenomenon when small CdSe NCs (<4 nm) are subject to S2− treatment followed by incubation in the presence of air and light irradiation, whereas PL enhancement is not observed in large CdSe NCs (>4 nm) treated under the same conditions. Systematic characterization establishes the evolution of CdSe/CdS core–shell structures in small CdSe NCs arising from anion exchange between Se2− and S2−, which in conjunction with the subsequent incubation process accounts for the PL enhancement. Notably, 2.1 nm CdSe NCs treated with (NH4)2S exhibit a PL quantum yield (QY) as high as ∼40% after 2 days of incubation, which is comparable to that of conventional hydrophobic CdSe/CdS core–shell NCs synthesized at high temperatures. Our studies demonstrate that S2− ions can substantially substitute Se2− in small CdSe NCs in addition to replacing the surface-coating ligands, enabling highly luminescent, hydrophilic CdSe/CdS core–shell NCs at room temperature.
研究领域:
材料科学
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纳米技术
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光学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
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2012
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IF 2.234
Hucheng Zhang,Dong Xu,Jianji Wang
High fluorescence efficiency is desired for the practical applications of semiconductor nanocrystals (NCs) in many fields. However, reducing photoluminescence (PL) efficiency is usually observed after ligand exchanges on nanocrystal surfaces due to the generation of surface defects. Here, we report the preparation of polyvinylpyrrolidone-capped CdSe NCs (CdSe/PVP), and show the PL enhancement of CdSe/PVP NCs under UV radiation in the air. The experimental results indicate that the PL-enhanced mechanism of the NCs in methanol results from passivation of the lyates in that they act as the hole-acceptors. By screening of hole scavenger, furthermore, it is found that ditertbutyl peroxide is a better passivators of surface defects, and promotes the PL efficiency of CdSe/PVP NCs to achieve a value 110 times higher than that of as-prepared CdSe/PVP NCs. The photopassivation in the presence of organic molecules provides a prefertial, inexpensive path to harvest NCs with high PL efficiency.
研究领域:
材料科学
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光学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Nanomaterials
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2019
·Vol. 2019
·期 1
·1251598
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IF 2.233
He-Ping Shi,Da-Wei Lin,Rui-feng Wu
Carboxyl end-functionalized poly(3-hexylthiophene) (P3HT-COOH) was grafted chemically with CdSe nanocrystals (NCs) by a phosphine-free method. The particle quality of P3HT-COOH/CdSe nanocomposites was better than that of P3HT/CdSe nanocomposites, which were synthesized using the same method. Nanocrystals with controllable particle size exhibited a wurtzite crystalline structure and showed excellent nanocrystal dispersion in the P3HT-COOH matrix. Photoluminescence (PL) characterization performed on nanocomposites suggested the efficient charge transfer at the P3HT-COOH/CdSe interface. This approach based on the phosphine-free method is not only environmentally friendly but also highly efficient.
研究领域:
材料科学
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纳米技术
✓ 已验证
DOI
高影响因子
CHEMISTRY OF MATERIALS
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2022
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IF 10.508
Linxi Wang,Xudong Qian,Yang Ren,Hairui Lei,Xiaofei Hu,Dongdong Chen,Jiongzhao Li,Xiaogang Peng
The CdS shells are epitaxially grown onto monodisperse zinc-blende CdSe core nanocrystals in octadecene mixed with fatty amines, with the volume fraction of fatty amines in the epitaxy solution (VNH2) varying between 0 and 100%. The shape─except the nanoplatelets from the reactions with medium VNH2 (especially 20% VNH2)─and surface ligands of the resulting CdSe/CdS core/shell nanocrystals from all reactions can be unified through a two-step surface treatment. The internal lattice defects originated from zinc-blende/wurtzite stacking fault(s), i.e., wurtzite lattice domain(s) in the CdS shells and twin fault(s) in the zinc-blende region, can be systematically controlled by varying the VNH2 and remain unaltered during the surface treatments. Both twin faults and wurtzite CdS lattice domains neither affect the electronic structure of the core/shell nanocrystals nor create internal electronic defects for the nanocrystals. Photoluminescence decay dynamics of the dot-shaped core/shell nanocrystals with solely twin faults can be mono-exponential and near-unity radiative decay, but photoluminescence of those with wurtzite CdS domains would always decay with double-exponential even if the photoluminescence quantum yield is unity. The results here imply that the most common lattice defects related to the stacking faults for II–VI and III–V semiconductor nanocrystals can be managed for achieving high-quality optical properties.
研究领域:
材料科学
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纳米技术
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半导体物理
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光学性质
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）