MATERIALS RESEARCH BULLETIN
·
2014
·
IF 1.968
Xin Zhou,Xianghua Zeng,Xiaoqing Yan,Weiwei Xia,Yuxue Zhou,Xiaoshuang Shen
Single-crystalline ZnS nanoparticles with a zinc-blende crystal structure have some microdefects such as stacking faults and nanotwins. In contrast, ZnS nanorods have a wurtzite crystal structure, which grows along the [0 0 0 1] direction, although some nanorods display the intergrowth of a minor zinc-blende phase and the major wurtzite phase, which forms stacking faults or zinc-blende/wurtzite ZnS nanotwins. Raman spectroscopy measurements reveal surface phonons and longitudinal optical phonons in the nanoparticles, nanorods and doublet phonons that are associated with the transversal optical phonons of the A1 and E1 modes in only the nanorods. The first-order longitudinal optical phonon mode exhibits a blueshift of 6 cm −1 when the particle size increases from 5 to 15 nm, but there is no shift in the range of 15–30 nm because of quantum confinement and microdefects.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Journal of the American Chemical Society
·
2021
·
IF 15.419
Jun-Nan Yang,Tian Chen,Jing Ge,Jing-Jing Wang,Yi-Chen Yin,Yi-Feng Lan,Xue-Chen Ru,Zhen-Yu Ma,Qun Zhang,Hong-Bin Yao
Lead halide perovskite nanocrystals (PNCs) are emerging as promising light emitters to be actively explored for high color purity and efficient light-emitting diodes. However, the most reported lead halide perovskite nanocrystal light-emitting diodes (PNCLEDs) encountered issues of emission line width broadening and operation voltage elevating caused by the quantum confinement effect. Here, we report a new type of PNCLED using large-size CsPbBr3 PNCs overly exceeding the Bohr exciton diameter, achieving ultranarrow emission line width and rapid brightness rise around the turn-on voltage. We adopt calcium-tributylphosphine oxide hybrid ligand passivation to produce highly dispersed large-size colloidal CsPbBr3 PNCs with a weak size confinement effect and also high photoluminescence quantum yield (∼85%). Utilizing these large-size PNCs as emitters, we manifest that the detrimental effects caused by the quantum confinement effect can be avoided in the device, thereby realizing the highest color purity in green PNCLED, with a narrow full width at half-maximum of 16.4 nm and a high corrected maximum external quantum efficiency of 17.85%. Moreover, the operation half-life time of the large-size PNCLED is 5-fold of that based on smaller-size PNCs. Our work provides a new avenue for improving the performance of PNCLEDs based on unconventional large-size effects.
研究领域:
材料科学
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光学工程
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale
·
2020
·Vol. 12
·期 32
·17113-17120
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IF 6.895
Ziren Xie,Xingjun Li,Renfu Li,Shan Lu,Wei Zheng,Datao Tu,Yanhui Feng,Xueyuan Chen
The metal halide perovskite quantum dots (APbX3 PeQDs; A = Cs or CH3NH3; X = Cl, Br or I) have emerged as a new type of promising optoelectronic material for light-emitting and photovoltaic applications because of their excellent optical properties. However, the precise control over the size and photoluminescence (PL) emission of APbX3 PeQDs remains a great challenge, which has been one of the main obstacles to the applications of PeQDs. Herein, we report a unique strategy for in situ confined growth of MAPbBr3 (MA = CH3NH3) PeQDs by using porous metal–organic framework (MOF) UiO-66 as a matrix. By introducing Pb(Ac)2 and MABr precursors into the pores of UiO-66 via a stepwise approach, ultrasmall MAPbBr3 PeQDs were in situ grown in the matrix with the size tuned from 6.4 to 3.3 nm by changing the concentration of the Pb(Ac)2 precursor. Accordingly, the PL emission wavelength of the resulting MAPbBr3 PeQDs was blue-shifted from 521 to 486 nm with the size reduction, owing to the strong quantum confinement effect of the PeQDs. Due to the surface passivation effect endowed by the UiO-66 matrix, the ultrasmall MAPbBr3 PeQDs also displayed a high PL quantum yield (PLQY) of 43.3% and a long PL lifetime of 100.3 ns. This study proposes a new strategy to prepare ultrasmall PeQDs and effectively control their sizes and PL emissions, which may open up new avenues for the development of high-performance luminescent PeQDs for diverse applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Crystals
·
2021
·Vol. 11
·期 9
·1132
·
IF 2.589
Lianxing Liao,Kunhua Quan,Xiangshi Bin,Ruosheng Zeng,Tao Lin
Bandgap tunability through ion substitution is a key feature of lead halide perovskite nanocrystals (LHP-NCs). However, the low stability and low luminescent performance of CsPbCl3hinder their full-color applications. In this work, quantum confinement effect (QCE) was utilized to control the bandgap of CsPbBr3NCs instead of using unstable CsPbCl3, which possess much higher emission efficiency in blue spectra region. Studies of microstructures, optical spectra and carrier dynamics revealed that tuning the reaction temperature was an effective way of controlling the NC sizes as well as QCE. Furthermore, the obtained CsPbBr3NCs were encapsulated in a PDMS matrix while maintaining their size distribution and quantum-confined optoelectronic properties. The encapsulated samples showed long-term air and water stability. These results provide valuable guidance for both applications of LHP-NCs and principal investigation related to the carrier transition in LHP-NCs.Keywords:lead halide perovskites;nanocrystals;quantum confinement effect;carrier lifetimes
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 48
·19020-19034
·
IF 3.069
Fu Yang,Shuying Gao,Yun Ding,Sheng Tang,Haifeng Chen,Jianjun Chen,Jianfeng Liu,Zhen Yang,Xiaocai Hu,Aihua Yuan
The confinement of refined catalytically active substances in special nanospaces is beneficial for promoting reaction processes by taking advantage of the quantum confinement effect and enlarged atomic efficiency. Herein, we present a redox nanoporous molecular sieve nanocatalyst containing size-confined active MnOx in the siliceous nanospace of mesopores via a functional micelle-assisted in situ embedding strategy. We also demonstrate its excellent environmental catalytic efficiency toward the oxidative degradation of methyl orange in the liquid phase (8 min) and volatile toluene in the gas phase (T90/T100 = 225/240 °C, under the mass space velocity of 60 000 ml g−1 h−1 and concentration of 1000 ppm, which surpass noble metal catalysts and most composite catalysts). This was achieved by virtue of eliminating diffusion limitations, and great active atom-efficiency. In this synthetic strategy, the well-made resultant MnOx had a refined size and greater interaction with diffusing reactant molecules without impeding their diffusion and mass transfer. Excellent and durable catalytic efficiency was demonstrated, due to the superior characteristics concerning the great dispersion of MnOx and favorable structure, thereby confirming that high catalytic removal efficiency depends on the amount of accessible MnOx rather than the loading of active species. Our findings provide the first example of a heterogeneous environmental catalyst that affords highly efficient catalytic elimination of organic contaminants in both liquid and gaseous systems.
研究领域:
环境科学
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材料科学
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催化化学
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2014
·
IF 4.835
Yejun Zhang,Yongsheng Liu,Chunyan Li,Xueyuan Chen,Qiangbin Wang
Ag2S quantum dots (QDs) have attracted increasing attention due to their appealing optical properties in the near-infrared regime. However, a full understanding of the quantum confinement effect of Ag2S QDs has not been achieved so far. Herein, for the first time, the size-dependent excited state optical properties of Ag2S QDs are systematically investigated by photoluminescence (PL), PL excitation (PLE), and time-resolved PL spectroscopy. Experimentally, we determine the exciton Bohr radius of Ag2S QDs as 2.2 nm, which is highly consistent with theoretical results.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 45
·28410-28419
·
IF 3.361
Shu Zhou
We report the rapid separation and purification of lead halide perovskite quantum dots (QDs) in a nonpolar solvent by using a convenient and efficient differential separation method. Size-selective precipitation effectively separates the perovskite QDs from larger aggregates and provides direct evidence for strong quantum confinement in the photoluminescence (PL). Significantly, the size-selected perovskite QDs are readily well-dispersed in a nonpolar solvent and remain stable in ambient air (humidity > 60%) for >20 days. These enable measurement of the electronic band structure of versatile perovskite QDs as a function of size for the first time. Despite a clear blue-shift of the optical bandgap, the lowest unoccupied molecular orbital (LUMO) readily moves towards the vacuum level while the highest occupied molecular orbital (HOMO) changes slightly, in good agreement with that observed in the quantum size effect tuning of quasi-2D perovskites and colloidal semiconductor QDs. The results demonstrate the possibility of utilizing differential centrifugation as a novel method to attain size-dependent tunability for property-specific perovskite-QD based optoelectronic applications.
研究领域:
材料科学
·
光电子学
✓ 已验证
DOI
PubMed
高影响因子
Nano Research
·
2024
·
IF 9.5
Chen Yue,Zhang Xiaoyu,Jiang Jinzhou,Chen Gaoyu,Zhou Kunhong,Zhang Xinwen,Li Fajing,Yuan Caojin,Bao Jianchun,Xu Xiangxing
All inorganic metal halide perovskite nanocrystals (NCs) have attracted much attention for their outstanding optoelectronic properties, which can be tuned by the composition, surface, size and morphology in nanoscale. Herein, we report the microfluidic synthesis of hollow CsPbBr 3 perovskite NCs through the nanoscale Kirkendall effect. The formation mechanism of the hollow structure (Kirkendall void) controlled by the temperature, flow rate, ratios of precursors and ligands was investigated. Compared with the solid CsPbBr 3 NCs of the same size, the hollow CsPbBr 3 NCs exhibit blue shifts in ultraviolet–visible (UV–vis) absorption and photoluminescence (PL) spectra, and remarkably longer PL average lifetime (~ 98.2 ns). Quantum confinement effect, inner surface induced additional trap states and lattice strain of the hollow CsPbBr 3 NCs were discussed in understanding their unique optoelectronic properties. The hollow CsPbBr 3 NC based photodetector exhibits an outstanding negative photoconductivity (NPC) detectivity of 8.9 × 10 12 Jones. They also show potentials in perovskite NC based photovoltaic and light emitting diodes (LEDs).
研究领域:
材料科学
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光学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2019
·
IF 13.903
Qinwei Wei,Songfeng Pei,Guodong Wen,Kun Huang,Zhaohong Wu,Zhibo Liu,Wei Ma,Hui-Ming Cheng,Wencai Ren
The strong quantum confinement effect as well as abundant edges and oxygen functional groups enable nano-graphene oxide (NGO) a variety of intriguing applications such as catalysis, bioimaging, drug delivery and photovoltaic devices. However, the development of NGO is severely hindered because of the difficulty in controlled mass production. Here, we report the efficient synthesis of NGO with a high yield of ∼40 wt % by water electrolytic oxidation of glassy carbon (GC). The NGO shows a high oxidation degree (C/O atomic ratio, ∼1.4) and excellent dispersion stability. Moreover, its size can be easily tuned by the graphitization degree of GC, which enables the controlled synthesis of NGO with average size of 4, 8, and 13 nm and different oxygen functional groups. As metal-free catalysts, the 13 nm sized NGO is found to be beneficial for the oxidative coupling reaction of benzylamine, while the 4 nm sized NGO shows a conversion rate of 88 times higher than 13 nm sized NGO for the oxidation reaction of benzene. In addition, the water electrolytic oxidation mechanism of graphitic materials is systematically studied. It is found that sulfuric acid has a protective effect on the graphite electrode during the water electrolytic oxidation process, and 50 wt % sulfuric acid solution well balances the protection and oxidation processes, leading to the highest oxidation efficiency and production rate.
研究领域:
材料科学
·
催化化学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FLUORESCENCE
·
2021
·Vol. 31
·期 2
·509-516
·
IF 2.217
Zuo Pengli,Zhang Jingyu,Zhou Yuqing,Xie Ningjie,Xiao Deli
Fluorescent carbon nanoparticles exhibit merits in terms of photochemical stability, functional modification flexibility and excellent biocompatibility. Currently, fluorescent carbon nanoparticles are often obtained by bottom-up or up-bottom strategies. So far, there has been no literature concerning spontaneous formation of fluorescent carbon nanoparticles. However, we have successfully found that fluorescent carbon nanoparticles can form spontaneously in the glutaraldehyde solution. Then further investigations were conducted on the storage time, pH and temperature, which could affect the fluorescence intensity of glutaraldehyde solution. The results indicate that the value of the fluorescence intensity will increase with the extension of the storage time. Moreover, the fluorescence mechanism of the glutaraldehyde solution was studied according to its properties and experiment results. Transmission electron microscopy was used to demonstrate nanoparticles in the glutaraldehyde solution. It’s assumed that such phenomenon is probably attributed to the conjugated structure resulting from the polymerization of glutaraldehyde and the quantum confinement effect owing to the nanoparticles formed by the aggregation of polymers. Therefore, the spontaneous fluorescence produced by glutaraldehyde solution provides a simple and environmentally-friendly way to prepare fluorescent carbon nanoparticles.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Small
·
2019
·Vol. 16
·期 4
·1905700
·
IF 10.856
Bo Yan,Chun Du,Guowei Yang
Codoping of N and O in ultrathin graphitic carbon nitride (g-C 3 N 4 ) nanosheets leads to an inner electric field. This field restrains the recombination of photogenerated carriers and, thus, enhances hydrogen evolution. The layered structure of codoped g-C 3 N 4 nanosheets (N-O-CNNS) not only provides abundant sites of contact with the reaction medium, but also decreases the distance over which the photogenerated electron–hole pairs are transported to the reaction interface. Quantum confinement in the ultrathin structure results in an increased bandgap and makes the photocatalytic reaction more favorable than bulk g-C 3 N 4 . Under visible light irradiation, N-O-CNNS with 3 wt% Pt achieves a hydrogen evolution rate of 9.2 mmol g −1 h −1 and a value of 46.9 mmol g −1 h −1 under AM1.5 with 5 wt% Pt. Thus, this work paves the way for designing efficient nanostructures with increased separation/transfer efficiency of photogenerated carriers and, hence, increased photocatalytic activities.
研究领域:
材料科学
·
能源化学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NANOTECHNOLOGY
·
2022
·Vol. 33
·期 50
·505601
·
IF 3.953
Xinchao Liang,Jinqian Hao,Pengyu Zhang,Chuang Hou,Guoan Tai
Borophene has attracted extensive interests owing to its distinct structural, electronic and optical properties for promising potential applications. However, the structural instability and need of metal substrate for deposition of borophene seriously restrict the exploration of its exceptional physical and chemical properties and further hamper its extensive applications towards high-performance electronic and optoelectronic devices. Here, we reported the synthesis of high-quality freestanding α-rhombohedral borophene nanosheets by a facile probe ultrasonic approach in different organic solvents. The results show that the nanosheets have high-quality in ethanol solution and have an average lateral size of 0.54 μm and a thickness of around 1.2 nm. Photoluminescence spectra indicate that a strong quantum confinement effect occurs in the nanosheets, which caused the increase of the band gap from 1.80 eV for boron powders and 2.52 eV for the nanosheets s. A nonvolatile memory device based on the nanosheets mixed with polyvinylpyrrolidone was fabricated, which exhibited a good rewriteable nonvolatile memory behavior and good stability.
研究领域:
材料科学
·
电子器件
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）