查找使用阿拉丁产品的科研文献

Monodisperse CdSe Quantum Dots Encased in Six (100) Facets via Ligand-Controlled Nucleation and Growth

Liulin Lv,Jiongzhao Li,Yonghong Wang,Yufei Shu,Xiaogang Peng

Zinc-blende CdSe quantum dots (QDs) encased in six equal (100) facets are synthesized in a noncoordinating solvent. Their monodispersed size, unique facet structure, and single crystallinity render the narrowest ensemble photoluminescence for CdSe QDs (full width at half-maximum being 52 meV). The nucleation stage can selectively form small-size CdSe QDs (≤3 nm) as seeds suited for the growth of cube-shaped QDs by reducing the concentration of cadmium carboxylates (Cd(RCOO)2) as the sole source of ligands. While resulting in poorly controlled nucleation, chloride-ion ligands introduced in the form of soluble CdClx(RCOO)1–x (x = 0.1∼0.2) would thermodynamically stabilize the cadmium-terminated (100) facets yet kinetically accelerate the deposition of selenium ions onto the (100) facets. Results suggest that it is fully feasible to synthesize QDs simultaneously with monodisperse size and surface structure through ligand-controlled nucleation and growth.

A novel fluorescent probe for H2O2 detection based on CdSe@ZnS quantum dots/Ag nanocluster hybrid

Zhiqiang Zhou,Liyun Yang,Ling Huang,Yuanping Liao,Yi Liu,Qi Xiao

The selective and quantitative detection of H 2 O 2 is important for its employment in physiological, environmental and industrial applications. In this paper, a sensitive and selective strategy for H 2 O 2 detection was established based on the fluorescence quenching of CdSe@ZnS quantum dots (QDs) by H 2 O 2 -mediated etching process of Ag nanoclusters (AgNCs). In this strategy, dihydrolipoic acid (DHLA) modified AgNCs were applied as H 2 O 2 response group, the existence of H 2 O 2 could initiate the oxidation of AgNCs and the production of Ag + . CdSe@ZnS QDs are very sensitive to Ag + , which could give rise to the effective fluorescence quenching of CdSe@ZnS QDs. Based on this strategy, the present fluorescent assay could realize the quantification detection of H 2 O 2 and the limit of detection is calculated to be 0.3 μM under the optimum conditions. Furthermore, CdSe@ZnS/AgNCs hybrid-based probe was applied to detecting H 2 O 2 in milk samples and showed a good recoveries results ranged from 95.8% to 112.0%, meaning the potential applicability of this strategy.

Enhanced performance of CdS/CdSe quantum dot-sensitized solar cells by long-persistence phosphors structural layer

Deng Yunlong,Lu Shuqi,Xu Zhiyuan,Zhang Jiachi,Ma Fei,Peng Shanglong

Light absorption plays an important role in improving the power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs). In this study, a multifunctional long-persistence phosphor (LPP) layer was introduced into the CdS/CdSe QDSSCs via a simple doctor blade method. The LPP layer can simultaneously improve the light harvesting and photo charge transfer in CdS/CdSe QDSSCs. As a result, their short-circuit current and corresponding PCE are effectively enhanced. The PCE can reach up to 5.07%, which is about 24% larger than that of the conventional CdS/CdSe QDSSCs without LPP layer. The solar cells can work in dark for a while due to the long-lasting fluorescence of the LPP layer. This research provides an effective way to improve the PCE of QDSSCs, and finds the possibility for all-weather QDSSCs.

Sensing tyrosine enantiomers by using chiral CdSe/CdS quantum dots capped with N-acetyl-l-cysteine

Fang Gao,Shiyao Ma,Xincai Xiao,Yan Hu,Dan Zhao,Zhike He

Despite of the importance of enantiomers , the fluorescence sensing of enantiomers and the interpretation of the “preferential interaction” still remain insufficiently explored. In this study, we report the recognition of tyrosine (Tyr) enantiomers by chiral N -acetyl- L -cysteine ( L -NAC) capped CdSe/CdS quantum dots (QDs) under alkaline experimental condition. L -Tyr could greatly quench the fluorescence of CdSe/CdS QDs, while D -Tyr displayed no effect on the fluorescence. The one-step synthesized chiral L -NAC-CdSe/CdS QDs demonstrated high selectivity for Tyr enantiomers. In particular, the mechanism of chiral recognition has been studied by UV/vis absorption spectra and circular dichroism (CD) spectra. The changes of intensity and sign of CD spectra corroborated the attachment of L -Tyr to the surface of QDs, which may be valuable aids in obtaining a better understanding of the possible mechanism of enantioselective recognition.

Hot-Electron-Induced Photochemical Properties of CdSe/ZnSe Core/Shell Quantum Dots under an Ambient Environment

Jiakuan Zhang,Jiongzhao Li,Zikang Ye,Jiting Cui,Xiaogang Peng

Using CdSe/ZnSe core–shell quantum dots (QDs) as a model, we systematically investigate the photochemical properties of QDs with the ZnSe shells under an ambient environment, which show almost opposite responses to either oxygen or water in comparison with CdSe/CdS core/shell QDs. While the ZnSe shells provide an efficient potential barrier for photoinduced electron transfer from the core to the surface-adsorbed oxygen, they also act as a stepping stone for hot-electron transfer directly from the ZnSe shells to oxygen. The latter process is so effective and competes favorably with ultrafast relaxation of hot electrons from the ZnSe shells to the core QDs, which can completely quench the photoluminescence (PL) with saturated adsorption of oxygen (1 bar) and initiate oxidation of the surface anion sites. Water can slowly eliminate the excess hole to neutralize the positively charged QDs, partially canceling the photochemical effects of oxygen. Alkylphosphines─through two distinctive reaction pathways with oxygen─stop the photochemical effects of oxygen and completely recover PL. With limited thickness (around two monolayers), the ZnS outer shells substantially slow down photochemical effects on CdSe/ZnSe/ZnS core/shell/shell QDs but cannot fully stop PL quenching by oxygen.

Effect of Different Ligands Coating on the Photovoltaic Performance of CdSe Quantum Dot-Sensitized Solar Cells

Yexin Chen,Shibing Zou,Wenhua Zou,Dongyang Wang,Junhong Duan,Weiqing Liu,Huaming Wu

Selective Optosensing of Aminoimidazo-Azaarenes (AIAs) by CdSe/ZnS Quantum Dots-embedded Molecularly Imprinted Silica Gel

Qiao Dan,Deng Qiliang,Wang Shuo

Background: The approach for the determination of aminoimidazo-azaarenes (AIAs) is urgently required due to their mutagenic activity and potential carcinogenicity. For this purpose, a CdSe/ZnS quantum dots (CdSe/ZnS QDs)-embedded molecularly imprinted silica gel with high selectivity and sensitivity was successfully prepared and applied to analyze such target. Methods: Herein, CdSe/ZnS QDs acted as the fluorescent probe, and molecularly imprinted silica gel as a recognition probe was synthesized on the surface of QDs via sol-gel method. 2- Aminobenzimidazole, which has a similar structure with AIAs, as well as low cost and low toxicity, was selected as the dummy template. Results: The material has a high imprinting factor (IF=6.15); the linear range of CdSe/ZnS@MIP as a fluorescent sensing material for AIAs is 0.5-20.0 μg L-1 with the limit of detection (LOD) of 0.25 μg L-1 (3σ/s). Moreover, the fluorescent materials have been further applied to determine AIAs in beef floss and grilled fish fillet with satisfactory recoveries (82.8-110.8 %), and the relative standard deviation (RSD) is < 5.5%. Conclusion: The proposed CdSe/ZnS QDs-embedded molecularly imprinted silica gel can be used to easily and selectively detect AIAs.

Improved Ink-Jet-Printed CdSe Quantum Dot Light-Emitting Diodes with Minimized Hole Transport Layer Erosion

Haodong Tang,Siqi Jia,Shihao Ding,Pai Liu,Jingrui Ma,Xiangtian Xiao,Xiangwei Qu,Haochen Liu,Hongcheng Yang,Bing Xu,Wei Chen,Guangyu Li,Zoe Pikramenou,Carl Anthony,Kai Wang,Xiao Wei Sun

Ink-jet printing is a promising deposition technology, which is capable of large-area fabrication and mask-free patterning. For ink-jet-printed quantum dot (QD) light-emitting diodes (LEDs), the QDs are commonly dissolved in a mixture of solvent and thickener ink system. However, the hole transport layer could be eroded by this QD ink, leading to a rough surface morphology and resulting in the leakage of carriers and low device performance. This phenomenon was first and directly observed by using an atomic force microscope and a cross-sectional scanning electron microscope. We, therefore, redesigned the annealing process of the hole transport layer to achieve an optimized smooth surface with a reduced number of defects for ink-jet-printed QD LEDs (QLEDs). Optimized morphology brings back a maximum luminance of over 30,000 cd/m2 and an external quantum efficiency of 7.52% for the ink-jet-printed red QLEDs using CdSe QDs, which are comparable to those of the spin-coated device. Moreover, the operation lifetime of the ink-jet-printed device is also enhanced by the restored surface morphology. An enhanced T50 lifetime of the ink-jet-printed device at 1000 cd/m2 is improved from 26 to 127 h, which converted to a long T50 lifetime of 8013 h, when operated at 100 cd/m2.

Highly Efficient and Stable CdSe/CdS Quantum Dot–Polyurethane Acrylate Composite Fluorescent Antennas for Optical Wireless Communication

Xuting Chen,Linqi Chen,Yuan Jiang,Yijing Wang,Hongbing Li,Jingzhou Li,Xinjie Li,Zeyi Wang,Hongxing Dong,Long Zhang

Fluorescent antennas (FAs) serve as promising optical concentrators for optical wireless communication (OWC) by overcoming the Étendue limit. Quantum dots-polymer nanocomposites exhibit superior optical properties for FAs. However, the poor chemical affinity between the surface ligands of quantum dots (QDs) and the polar functional groups in polymer matrices reduces interfacial compatibility, triggering ligand desorption and interparticle aggregation during photopolymerization. These effects severely degrade the photoluminescence efficiency and long-term stability, thus limiting the practical application of polymer-based FAs. Herein, a high-performance nanocomposite is demonstrated by embedding ODPA-passivated CdSe/CdS QDs into a polyurethane acrylate (PUA) matrix through doctor-blade coating and photopolymerization. Molecular dynamics simulations and density functional theory calculations reveal that QDs improve interfacial compatibility with PUA matrix through hydrogen-bond crosslinking between surface ligands and PUA hard segments, along with alkyl chain-induced plasticization of soft segments. Optimizing the QD concentration results in nanocomposites with a near-unity photoluminescence quantum yield of 99.15% and enhanced environmental stability. The sandwich-structured FA demonstrates a −3 dB bandwidth of 8.6 MHz, a 154 Mbps data rate using orthogonal frequency division multiplexing (OFDM) modulation. This work presents a readily processable nanocomposite system with high efficiency and stability, advancing OWC applications in terrestrial and underwater environments.

Enhanced Photovoltaic Performance of CdSe Quantum Dot-Sensitized Solar Cells Utilizing Sm–Eu Co-Doped TiO2 Photoanodes

Xiyuan Zhang,Wenhua Zou,Junhong Duan

In this study, titanium dioxide (TiO ${}_{{2}}\text {)}$ nanoparticles co-doped with varying ratios of Eu and Sm were synthesized using a hydrothermal method. The energy bandgap ( ${E}_{\text {g}}\text {)}$ and conduction band minimum (CBM) of TiO₂ nanoparticles doped with 0.45 at% Sm@0.1 at% Eu were adjusted from 3.43 and −3.95 eV to 3.30 and −3.53 eV, respectively, determined from ultraviolet–visible (UV–Vis) absorption spectroscopy and ultraviolet photoelectron spectroscopy (UPS) measurements compared to undoped TiO₂. CdSe quantum dot-sensitized solar cells (QDSCs) based on TiO₂ doped with 0.45 at% Sm@0.1 at% Eu achieved an optimal power conversion efficiency (PCE) of 4.37%. Electrochemical impedance spectroscopy (EIS) revealed that the decrease in chemical capacitance ( ${\textit C}_{\mu }\text {)}$ and the increase in recombination resistance ( ${\textit R}_{\text {rec}}\text {)}$ of QDSCs based on 0.45 at% Sm@0.1 at% Eu-doped TiO₂ photoanodes facilitate charge extraction and suppress charge recombination at the TiO₂/electrolyte (EL) interface compared to undoped one.

Ultrafast-Broadband Photodetector with High Responsivity Based on an Interface-Engineered 2D Perovskite/CdSe Type-II Heterojunction

Yan Yang,Haiqiang Huang,Lei Liu,Qiuhong Tan,Yifei Huang,Lujun Yang,Hui Zhang,Xuejin Zhang,Feng Song,Yingkai Liu

Two-dimensional (2D) Ruddlesden–Popper perovskite phenylethylammonium lead iodide ((PEA)2PbI4) possesses potential photoelectronic properties and is considered to be an ideal material for photodetectors. However, single devices commonly suffer from low responsivity, slow response speed, and narrow detection range, which hinder their applications in imaging, communications, and artificial intelligence (AI). In this work, high-quality 2D (PEA)2PbI4 tetragons (TTs) were synthesized via a unique liquid–air interface floating method and integrated with cadmium selenide (CdSe) nanobelts (NBs) to construct a novel hybrid heterojunction photodetector. It confirms that the formation of type-II band alignment at the heterointerface enables efficient interfacial charge transfer. Notably, the (PEA)2PbI4/CdSe heterojunction hybrid device exhibits exceptional performance under 450 and 682 nm monochromatic illumination: extremely high responsivity (R) (2.80 × 103 and 6.39 × 103 A/W), excellent detectivity (D*) (4.09 × 1013 and 9.32 × 1013 Jones), large external quantum efficiency (EQE) (7.74 × 105% and 1.16 × 106%), and remarkable Ion/Ioff ratio (3.60 × 105 and 8.66 × 105), as well as fast response speeds (rise/decay time: 108/265 μs and 86/196 μs). Furthermore, the hybrid device overcomes the intrinsic bandgap limitation of (PEA)2PbI4, extending its photoresponse to cover nearly the entire visible spectrum and demonstrating reliable imaging capability. This study provides an innovative strategy for developing high-performance photodetectors with significant practical application potential.

Designing of Ag/CdSe/g-C3N4 nanocomposite for CO2 conversion and dye degradation: insight into the mechanism

Ali Zubair,Khan Iltaf,Wang Chunjuan,Ali Farman,Mujahid Laiba,Zaman Saeed,Arif Umar,Chen Xiaohu,Ali Nisar

Dyes represent a major class of water pollutants worldwide, posing significant threats to aquatic ecosystems and the environment due to their discharge into industrial wastewater without treatment. Thus, before releasing organic colors and their derivatives into rivers, they must be degraded using heterogeneous photocatalysts. Similarly, burning fossil fuels releases massive amounts of CO 2 into the atmosphere, exacerbating global warming and environmental devastation. Herein, we report the design and fabrication of Ag/CdSe/g-C 3 N 4 (i.e., Ag/CdSe/CN) as a highly efficient photocatalyst for the degradation of Toluidine Blue dye and CO 2 conversion to value-added products. X-ray diffraction analysis confirmed the crystalline nature of the as-synthesized photocatalyst. SEM and TEM analysis revealed that Ag and CdSe nanoparticles are uniformly dispersed on the surface of a 2D sheet-like structure for CN. The photocatalytic performance of the photocatalysts was explored at different parameters such as dye and photocatalyst doses, pH, and time. The as-fabricated Ag/CdSe/CN photocatalyst revealed exceptional performance for Toluidine Blue dye degradation under visible light irradiation, with a notable 92.3% degradation at pH 13, which is remarkably higher than those of the CdSe/CN, CdSe, and CN photocatalysts. Additionally, the Ag/CdSe/CN photocatalyst revealed outstanding performance for visible light catalytic CO 2 conversion to CH 4 (i.e., 9 μmol g⁻ 1  h⁻ 1 ) and CO (28 μmol g⁻ 1  h⁻ 1 ), in comparison to the reference samples. This work will provide a new route for the design and fabrication of highly efficient photocatalysts for environmental applications. Graphical abstract Graphical abstract showing the design of Ag/CdSe/g-C 3 N 4 nanocomposite for CO 2 conversion and dye degradation