Journal articles: 'ZnS QDs'

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Liu, Jing, Ming Ying, Yu Ling Tan, and Bo Xi. "Photoluminescent Characteristics of ZnS Quantum Dots Synthesized in Non-Aqueous-Phase." Advanced Materials Research 750-752 (August 2013): 991–94. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.991.

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ZnS quantum dots (ZnS QDs) synthesized in aqueous solution is easy to gather a mass, which always results in low quantum yield. So, in this study benzene was used as reaction medium in which ZnS QDs with different hues were synthesized, and the hues of ZnS QDs were depend on the molar ratio of Zn (CH3COO)2 and Na2S·9H2O. The results show the emission spectra of ZnS QDs shifts with the change of the precursor molar ratio but the absorption peak at 310nm is not. The emission peaks centered at 430nm and 580nm at higher molar ratio [Zn2+]/[S2-] with blue-violet emitting phosphors; but, ZnS QDs synthesized at higher molar ratio [S2-]/[Zn2+] have orange-red emission at 580nm only. The X-ray diffraction analysis shows the crystallinity of ZnS QDs is better at [Zn2+]/[S2-]=1:10, which are typical zinc blend with nanorod structure.

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Fu, Yan, Daekyoung Kim, Wei Jiang, Wenping Yin, Tae Kyu Ahn, and Heeyeop Chae. "Excellent stability of thicker shell CdSe@ZnS/ZnS quantum dots." RSC Advances 7, no. 65 (2017): 40866–72. http://dx.doi.org/10.1039/c7ra06957j.

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Evolution of the long-term (400 h) thermal stability of green CdSe@ZnS alloyed core/shell QDs (A-QDs) and CdSe@ZnS/ZnS (alloyed core/shell)/thick shell QDs (AS-QDs) under 85 °C, 85% relative humidity conditions in air.

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Chang, Kai-Ping, Yu-Cheng Yeh, Chung-Jui Wu, Chao-Chun Yen, and Dong-Sing Wuu. "Improved Characteristics of CdSe/CdS/ZnS Core-Shell Quantum Dots Using an Oleylamine-Modified Process." Nanomaterials 12, no. 6 (March 9, 2022): 909. http://dx.doi.org/10.3390/nano12060909.

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CdSe/CdS with ZnS/ZnO shell quantum dots (QDs) are synthesized by a one-pot method with various oleylamine (OLA) contents. The crystal structures of the QDs were analyzed by X-ray diffractometry, which showed ZnS diffraction peaks. It was represented that the ZnS shell was formed on the surface of the CdSe/CdS core. Interestingly, QDs with a high OLA concentration exhibit diffraction peaks of ZnS/ZnO. As a result, the thermal stability of QDs with ZnS/ZnO shells exhibits better performance than those with ZnS shells. In addition, the photoluminescence intensity of QDs with ZnS/ZnO shells shows a relatively slow decay of 7.1% compared with ZnS shells at 85 °C/85% relative humidity aging test for 500 h. These indicate that QDs with different OLA modifications can form ZnS/ZnO shells and have good stability in a harsh environment. The emission wavelength of QDs can be tuned from 505 to 610 nm, suitable for micro-LED display applications.

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Liu, Wei, Xian Lan Chen, Ju Cheng Zhang, Yun Hui Long, Ling Shi, and Na Wu. "Preparation ZnS Quantum Dots via Water-Phase Synthesis Method." Advanced Materials Research 706-708 (June 2013): 230–33. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.230.

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With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.

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Hong, Wuding, Huijuan Kuang, Xingping He, Lin Yang, Pengfei Yang, Bolu Chen, Zoraida Aguilar, and Hengyi Xu. "CdSe/ZnS Quantum Dots Impaired the First Two Generations of Placenta Growth in an Animal Model, Based on the Shh Signaling Pathway." Nanomaterials 9, no. 2 (February 14, 2019): 257. http://dx.doi.org/10.3390/nano9020257.

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The toxicity, especially the transgenerational toxicity of quantum dots (QDs) in vivo, is still scarcely understood in spite of great promising applications of QDs in biomedicine. In this study, the maternal status, pregnancy outcome, and fetus development of parental generation (P0) to offspring in three generations (F3) were investigated after Kunming mice perinatal (GD 13-PND 5) exposure to Cd containing QDs (CdSe/ZnS QDs) and CdCl2. The results show CdSe/ZnS QDs induced placenta injuries in P0 and diminished placenta diameters in F1 and F2. Bodyweight growth decreased in the CdSe/ZnS QDs treatment group in the F1 and F2 generation. Additionally, CdSe/ZnS QDs significantly altered the expression of key genes in the Shh signal pathway. Overall, this study exhibited that the CdSe/ZnS QDs exposure during perinatal period impaired placenta growth in the first two generations, but not on the third generation. The toxicological actions of the CdSe/ZnS QDs might be through the effects on the Shh signal pathway.

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Su, Yu Yang, Kai Ling Liang, and Chyi Ming Leu. "Cd-Free Quantum Dot Dispersion in Polymer and their Film Molds." Advances in Science and Technology 98 (October 2016): 38–43. http://dx.doi.org/10.4028/www.scientific.net/ast.98.38.

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Indium phosphide (InP) quantum dots (QDs) with luminescence tunable over the entire visible spectrum were prepared by the conventional hot injection method. InP QDs are considered alternatives to Cadmium containing QDs for application in light-emitting devices because of showing similar optical properties to those containing toxic heavy metals. The multishell coating was shown to improve the photoluminescence quantum yield (QY) of InP QDs more strongly than the conventional ZnS shell coating. QY values were more than 60% along with FWHM of 41-73 nm can be routinely achieved, making the optical performance of InP/ZnS/ZnS or InP/ZnS/SiO2 QDs comparable to that of InP/ZnS QDs. These QDs and the polymer dissolved in the appropriate solvent and deposited by casting to give homogeneous films and showed a good level of dispersion of the QDs within the polymer.

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Lian, Linyuan, Youyou Li, Daoli Zhang, and Jianbing Zhang. "Synthesis of Highly Luminescent InP/ZnS Quantum Dots with Suppressed Thermal Quenching." Coatings 11, no. 5 (May 17, 2021): 581. http://dx.doi.org/10.3390/coatings11050581.

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InP quantum dots (QDs) are promising down-conversion phosphors for white light LEDs. However, the mainstream InP QDs synthesis uses expensive phosphorus source. Here, economic, in situ-generated PH3 is used to synthesize InP QDs and a two-step coating of ZnS shells is developed to prepare highly luminescent InP/ZnS/ZnS QDs. The QDs show a photoluminescence quantum yield as high as 78.5%. The emission can be tuned by adjusting the halide precursor and yellow emissive InP/ZnS/ZnS QDs are prepared by judiciously controlling the synthetic conditions. The yellow QDs show suppressed thermal quenching and retain >90% room temperature PL intensity at 150 °C for the growth solution. Additionally, the PL spectrum matches with the eye sensitivity function, resulting in efficient InP QD white light LEDs.

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Chen, Xuan Lin, Yu Qiu Qu, Gui Fan Li, Hong Wei, Liu Yang Zhang, and Li Min An. "Effect of Charge Transferring Materials on Photoluminescence Properties of CdSe/ZnS Quantum Dots." Advanced Materials Research 981 (July 2014): 879–82. http://dx.doi.org/10.4028/www.scientific.net/amr.981.879.

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The CdSe/ZnS core/shell quantum dots (QDs) were synthesized and characterized with absorption spectrometry, photoluminescence (PL) spectrometry and transmission electron microscopy. PL quenching of colloidal CdSe/ZnS QDs in the presence of charge transferring material was studied by means of steady-state and time-resolved PL spectroscopy. With increasing charge transferring materials concentration in the CdSe/ZnS QDs solution, the PL intensity and lifetime of CdSe/ZnS QDs decrease gradually. The quenching efficiency of CdSe/ZnS QDs decrease with increasing the oxidation potential of charge transferring materials. Based on the analysis, there are two pathways in the PL quenching process: static quenching and dynamic quenching. The dynamic quenching is correlated with hole transfer from QDs to the charge transferring materials.

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Abib, Mukerem Helil, Taotao Chen, Enze Xu, Man Wang, and Yang Jiang. "Synthesis of Eco-Friendly High PL Lifespan Manganese-Doped CuInZnS/ZnS QDs for White LED Applications." Journal of Nanoscience and Nanotechnology 20, no. 10 (October 1, 2020): 6286–94. http://dx.doi.org/10.1166/jnn.2020.18585.

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Environmentally friendly and long PL lifespan Mn-doped CuInZnS (Mn:CIZS) and CuInZnS/ZnS (Mn:CIZS/ZnS) QDs, with respective red and yellow emissions, were synthesized using nontoxic precursors via a facile dual-step process based on the one-pot method. The resulting Mn:CIZS and Mn:CIZS/ZnS QDs exhibited confirmed strong red and yellow photoluminescence emissions at approximately 654 nm and 580 nm, respectively. The measured PL decay lifespan for the Mn: CIZS QDs is 2.52 μs due to well-organized surface passivation through the ZnS shell; the average PL lifespan for the Mn:CIZS/ZnS QDs is extended to 6.28 μs. Moreover, the WLEDs were composed of the Mn:CIZS/ZnS QDs. The resulting WLEDs offered admirable optical attributes, such as an excellent Ra of 89, a low Tc of 5075 K and radiant white light emanation at 60 mA functional current. Therefore, the outputs highlight the Mn:CIZS/ZnS QDs as hopeful cadmium-free resources for the interest of optoelectronics exploration.

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Zhang, Xin, Meng Wang, Yating Zhang, Pan Zhao, Jiamei Cai, Yunjian Yao, and Jiarong Liang. "Preparation of Molecularly Imprinted Cysteine Modified Zinc Sulfide Quantum Dots Based Sensor for Rapid Detection of Dopamine Hydrochloride." Molecules 28, no. 9 (April 22, 2023): 3646. http://dx.doi.org/10.3390/molecules28093646.

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By combining surface molecular imprinting technology with cysteine-modified ZnS quantum dots, an elegant, molecularly imprinted cysteine-modified Mn2+: ZnS QDs (MIP@ZnS QDs) based fluorescence sensor was successfully developed. The constructed fluorescence sensor is based on a molecularly imprinted polymer (MIP) coated on the surface cysteine-modified ZnS quantum dots and used for rapid fluorescence detection of dopamine hydrochloride. The MIP@ZnS quantum dots possess the advantages of rapid response, high sensitivity, and selectivity for the detection of dopamine hydrochloride molecules. Experimental results show that the adsorption equilibrium time of MIP@ZnS QDs for dopamine hydrochloride molecules is 12 min, and it can selectively capture and bind dopamine in the sample with an imprinting factor of 29.5. The fluorescence quenching of MIP@ZnS QDs has a good linear (R2 = 0.9936) with the concentration of dopamine hydrochloride ranged from 0.01 to 1.0 μM, and the limit of detection is 3.6 nM. In addition, The MIP@ZnS QDs demonstrate good recyclability and stability and are successfully employed for detection of dopamine hydrochloride in urine samples with recoveries was 95.2% to 103.8%. The proposed MIP@ZnS QDs based fluorescent sensor provides a promising approach for food safety detection and drug analysis.

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Xu, Shi Chao, Yue Qian Yang, Yan Shan Liu, Heng Miao, Mei Dong, Juan Yang, Ji Mei Zhang, et al. "An Enhanced Luminescent CdTe/ZnS Core-Shell Quantum Dot: Synthesis, Characterization, and its Optical Properties." Advanced Materials Research 217-218 (March 2011): 212–15. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.212.

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The core-shell CdTe/ZnS quantum dots were prepared with an improved process in aqueous phase. CdTe QDs were synthesized under conditions of pH 9.1, 96 °C, refluxing for 5h, and which was used as core material; ZnS was formed as shell material to enhance the optical properties. Optical properties were characterized with fluorescence spectrum (FS), and morphology of QDs was investigated via transmission electron microscopy (TEM) method. Moreover, composition and formation of CdTe/ZnS core-shell QDs was characterized via x-ray diffraction (XRD) method. Optimum conditions were investigated to obtain the qualified CdTe/ZnS core-shell QDs, the results indicated QDs with high quantum yields and fluorescence intensity were achieved under conditions of pH 9.0, 45 °C, refluxing for 1h, and v/v/v ratio of CdTe/Na2S/ZnSO4 is 4/1/1. The TEM data indicated that average size of 5 nm CdTe core was prepared, and CdTe/ZnS core-shell QDs with average size of 11 nm were achieved under the optimum conditions. ca 30nm of red shift of a maximum emission wavelength from ca 530 nm (CdTe) to 560 nm (CdTe/ZnS) was observed via FS under the optimum conditions, which inferred the growth of QDs and formation of ZnS shells. Furthermore, the enhanced fluorescence intensity of CdTe/ZnS core-shell QDs was detected and over two times of fluorescence intensity was increased after formation of ZnS shell. The obtained QDs will have great potential application in biological researches and biosensing system based on fluorescence resonance energy transition (FRET).

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Iida, Kazutaka, and DaeGwi Kim. "Temperature-dependent photoluminescence properties of water-soluble CuInS₂ and CuInS₂/ZnS quantum dots." Journal of Applied Physics 132, no. 19 (November 21, 2022): 194306. http://dx.doi.org/10.1063/5.0105290.

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Although the photoluminescence (PL) of oil-soluble CuInS2 (CIS) quantum dots (QDs) has been widely investigated, the origin of PL in water-soluble CIS QDs is less well understood. Elucidation of the PL origin of water-soluble CIS QDs is an important issue in applications such as bioimaging and optical materials. Herein, we prepared CIS and CIS/ZnS QDs using a hydrothermal method and systematically investigated the temperature dependence of their PL properties. For both CIS and CIS/ZnS QDs, the temperature dependence of the PL intensity could be quantitatively understood by considering thermally activated nonradiative recombination processes. In contrast, the Stokes shift and PL decay time of the CIS/ZnS QDs showed a significantly different temperature dependence than those of the CIS QDs. This unusual temperature-dependent behavior of the CIS/ZnS QDs was attributed to carrier localization at the core/shell interface at low temperatures. The temperature dependence of the PL decay time of the CIS/ZnS QDs could be quantitatively explained using a phenomenological rate equation model that considered carrier localization at low temperatures.

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Qu, Yu Qiu, Liu Yang Zhang, Li Min An, Hong Wei, and Gui Fan Li. "Study on Photoluminescence Quenching of CdSe Core/Shell Quantum Dots with Organic Charge Transferring Material." Advanced Materials Research 981 (July 2014): 883–86. http://dx.doi.org/10.4028/www.scientific.net/amr.981.883.

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The effect of organic charge transferring material (CTM) on fluorescence of CdSe/ZnS and CdSe/CdS/ZnS core/shell quantum dots (QDs) are investigated by spectral methods. With the increase of organic molecular concentration, CTM can greatly quench the fluorescence of QDs and shorten the fluorescence lifetime of QDs. In the process of interacting with CTM, the efficiency of fluorescence quenching for CdSe/ZnS is significantly higher than that for CdSe/CdS/ZnS. The results of experiment show that the shell structure of QDs plays the major role in photoluminescence (PL) quenching. The mechanism of PL quenching of QDs is also analyzed.

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Byambasuren, Nyamsuren, Jiyeon Jo, Hyungduk Ko, Byeong-Kwon Ju, Ji Young Byun, and Ho Seong Jang. "Phosphine-Free-Synthesized ZnSe/ZnS Core/Shell Quantum Dots for White Light-Emitting Diodes." Applied Sciences 11, no. 21 (October 27, 2021): 10060. http://dx.doi.org/10.3390/app112110060.

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Blue-light-emitting ZnSe core (C) and ZnSe/ZnS core/shell (C/S) quantum dots (QDs) were synthesized with phosphine-free precursors by a thermal decomposition method in paraffin oil solvent and applied to QD-converted light-emitting diodes (LEDs). The optical properties of the synthesized ZnSe C and ZnSe/ZnS C/S QDs were characterized by absorption spectroscopy and photoluminescence spectroscopy. Additionally, the quantum efficiency of the QDs was investigated. Their structural properties were studied with X-ray crystallography and transmission electron microscopy. The ZnSe/ZnS C/S QDs showed deep-blue light peaking at 425 nm. The blue-light-emitting ZnSe/ZnS C/S QDs were used as color-converting materials for near-ultraviolet LED-pumped blue LEDs and combined with yellow-light-emitting Zn-Cu-In-S/ZnS C/S QDs to fabricate white LEDs. The white LEDs showed warm white light [(CIE x, CIE y) = (0.4088, 0.3987)], Tc = 3488 K, and Ra = 61.2]. The results indicate that the ZnSe/ZnS C/S QDs have good potential for white light application after further improvements to their optical properties.

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YU, ZHANGSEN, and XIYING MA. "SYNTHESIS AND PHOTOLUMINESCENCE OF WATER-SOLUBLE ZnS:Mn2+/ZnS QUANTUM DOTS BY NUCLEATION DOPING STRATEGY." Nano 06, no. 01 (February 2011): 75–79. http://dx.doi.org/10.1142/s1793292011002366.

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We report the synthesis of luminescent-doped core/shell quantum dots (QDs) of water-soluble manganese-doped zinc sulfide (ZnS:Mn2+/ZnS) . QDs of ZnS:Mn2+/ZnS were prepared by nucleation doping strategy, with thioglycolic acid (TGA) as stabilizer in aqueous solution. Structure and optical properties of the ZnS:Mn2+/ZnS core/shell quantum dots were characterized by X-ray diffraction and photoluminescence emission spectroscopy. The influence of the synthesis conditions on the luminescent properties of ZnS:Mn2+/ZnS QDs is discussed. Different Mn2+ concentrations, ratios of the TGA/ (Zn+Mn) and thickness of the ZnS shell were used. Results showed that the ZnS:Mn2+/ZnS QDs are water-soluble and have improved fluorescence properties. Therefore, Mn2+ -doped ZnS quantum dots could be potential candidates as fluorescent labeling agents in biology.

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Xu, Shi Chao, Heng Miao, Yue Qian Yang, Juan Yang, Ji Mei Zhang, Zhao Dai, Guo Zheng, et al. "Fluorescence Enhanced Quantum Dots: Its Synthesis, Optical Properties, and Ecotoxicity Research." Advanced Materials Research 152-153 (October 2010): 208–11. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.208.

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Quantum dots (QDs) are normally based on the semiconductor materials and widely used in biosensing, bioimaging, biolabeling, and biotreatment for their excellent properties. The ecotoxicity research of QDs correspondingly kept in rising in recent years. CdTe and CdTe/ZnS QDs were prepared via an improved process in aqueous phase, morphology of QDs was characterized with transmission electron microscopy, and optical properties were investigated via fluorescence spectrum. Ecotoxicity of CdTe and CdTe/ZnS were assayed by measuring the inhibitory growth of Rhodococcus sp. strain C1 when QDs existed in broth culture, which was screened from sewage, and its morphology was characterized with optical microscope and scanning electron microscope. CdTe QDs showed strong inhibitory effect against growth of Rhodococcus sp. strain C1, and little growth was observed after 72h cultivation. CdTe/ZnS QDs showed prophasic inhibition before 36h, and growth recovery was observed after 48h of cultivation. Enhanced optical properties and decreasing ecotoxicity were validated after ZnS shell formation, these results indicated that CdTe/ZnS QDs with core-shell structure has great potential in bio-applications.

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Mishra, Rajneesh Kumar, Gyu-Jin Choi, Hyeon-Jong Choi, and Jin-Seog Gwag. "ZnS Quantum Dot Based Acetone Sensor for Monitoring Health-Hazardous Gases in Indoor/Outdoor Environment." Micromachines 12, no. 6 (May 22, 2021): 598. http://dx.doi.org/10.3390/mi12060598.

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This study reports the ZnS quantum dots (QDs) synthesis by a hot-injection method for acetone gas sensing applications. The prepared ZnS QDs were characterized by X-ray diffraction (XRD) and transmission electron microscopy analysis. The XRD result confirms the successful formation of the wurtzite phase of ZnS, with a size of ~5 nm. Transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and fast Fourier transform (FFT) images reveal the synthesis of agglomerated ZnS QDs with different sizes, with lattice spacing (0.31 nm) corresponding to (111) lattice plane. The ZnS QDs sensor reveals a high sensitivity (92.4%) and fast response and recovery time (5.5 s and 6.7 s, respectively) for 100 ppm acetone at 175 °C. In addition, the ZnS QDs sensor elucidates high acetone selectivity of 91.1% as compared with other intrusive gases such as ammonia (16.0%), toluene (21.1%), ethanol (26.3%), butanol (11.2%), formaldehyde (9.6%), isopropanol (22.3%), and benzene (18.7%) for 100 ppm acetone concentration at 175 °C. Furthermore, it depicts outstanding stability (89.1%) during thirty days, with five day intervals, for 100 ppm at an operating temperature of 175 °C. In addition, the ZnS QDs acetone sensor elucidates a theoretical detection limit of ~1.2 ppm at 175 °C. Therefore, ZnS QDs can be a promising and quick traceable sensor nanomaterial for acetone sensing applications.

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Lu, Y., Y. Q. Zhang, and X. A. Cao. "Luminescence enhancement of colloidal quantum dots by strain compensation." MRS Proceedings 1547 (2013): 109–14. http://dx.doi.org/10.1557/opl.2013.579.

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ABSTRACTWe have investigated the effects of two different strain-relief bilayer shell structures on the luminescent properties of colloidal CdSe quantum dots (QDs). CdSe QDs with a strain-compensated ZnS/ZnCdS bilayer shell were synthesized using the successive ion layer adsorption and reaction technique and their crystallinity of was examined by X-ray diffraction. The QDs enjoyed the benefits of excellent exciton confinement by the ZnS intermediate shell and strain compensation by the ZnCdS outer shell. The resulting CdSe/ZnS/ZnCdS QDs exhibited 40% stronger photoluminescence and a smaller peak redshift upon shell growth compared to conventional CdSe/ZnCdS/ZnS core/shell/shell QDs with an intermediate lattice adaptor. CdSe/ZnS/ZnCdS QD light-emitting diodes (LEDs) had a luminance of 558 cd/m2 at 20 mA/cm2, 28% higher than that of CdSe/ZnCdS/ZnS QD-LEDs. The former also had better spectral purity. These results suggest that nanocrystal shells may be strain-engineered in a different way to achieve QDs of high crystalline and optical quality well suited for full-color display applications.

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BAHARI, ALI, MOHSEN ADELI, and SONIA MOHAMAD HOSSEINI. "SYNTHESIS OF HYBRID NANOMATERIALS USING LINEAR-DENDRITIC COPOLYMERS." Nano 06, no. 04 (August 2011): 301–11. http://dx.doi.org/10.1142/s1793292011002652.

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New types of hybrid nanomaterials consisting of CdSe and ZnS quantum dots were synthesized through noncovalent interactions. Polycitric acidpolyethylene glycolpolycitric acid linear-dendritic copolymers were synthesized and sonicated in the presence of amino-functionalized CdSe and ZnS quantum dots (QDs). Based on microscopy and spectroscopy investigations, it has been found that CdSe and ZnS QDs link together through linear-dendritic copolymers bridges. This strategy led to composites containing two types of QDs dispersed in a polymeric matrix. Optical properties of CdSe/ZnS hybrid nanomaterials depended on different factors that affect the noncovalent interactions between linear-dendritic copolymers and QDs.

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Hu, Siyi, Yu Ren, Yue Wang, Jinhua Li, Junle Qu, Liwei Liu, Hanbin Ma, and Yuguo Tang. "Surface plasmon resonance enhancement of photoluminescence intensity and bioimaging application of gold nanorod@CdSe/ZnS quantum dots." Beilstein Journal of Nanotechnology 10 (January 3, 2019): 22–31. http://dx.doi.org/10.3762/bjnano.10.3.

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Biological applications of core/shell near-infrared quantum dots (QDs) have attracted broad interest due to their unique optical and chemical properties. Additionally, the use of multifunctional nanomaterials with near-infrared QDs and plasmonic functional nanoparticles are promising for applications in electronics, bioimaging, energy, and environmental-related studies. In this work, we experimentally demonstrate how to construct a multifunctional nanoparticle comprised of CdSe/ZnS QDs and gold nanorods (GNRs) where the GNRs were applied to enhance the photoluminescence (PL) of the CdSe/ZnS QDs. In particular, we have obtained the scattering PL spectrum of a single CdSe/ZnS QD and GNR@CdSe/ZnS nanoparticle and comparison results show that the CdSe/ZnS QDs have an apparent PL enhancement of four-times after binding with GNRs. In addition, in vitro experimental results show that the biostability of the GNR@CdSe/ZnS nanoparticles can be improved by using folic acid. A bioimaging study has also been performed where GNR@CdSe/ZnS nanoparticles were used as an optical process for MCF-7 breast cancer cells.

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Horstmann, Cullen, Daniel S. Kim, Chelsea Campbell, and Kyoungtae Kim. "Transcriptome Profile Alteration with Cadmium Selenide/Zinc Sulfide Quantum Dots in Saccharomyces cerevisiae." Biomolecules 9, no. 11 (October 25, 2019): 653. http://dx.doi.org/10.3390/biom9110653.

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Quantum Dots (QDs) are becoming more prevalent in products used in our daily lives, such as TVs and laptops, due to their unique and tunable optical properties. The possibility of using QDs as fluorescent probes in applications, such as medical imaging, has been a topic of interest for some time, but their potential toxicity and long-term effects on the environment are not well understood. In the present study, we investigated the effects of yellow CdSe/ZnS-QDs on Saccharomyces cerevisiae. We utilized growth assays, RNA-seq, reactive oxygen species (ROS) detection assays, and cell wall stability experiments to investigate the potential toxic effects of CdSe/ZnS-QDs. We found CdSe/ZnS-QDs had no negative effects on cell viability; however, cell wall-compromised cells showed more sensitivity in the presence of 10 µg/mL CdSe/ZnS-QDs compared to non-treated cells. In CdSe/ZnS-treated and non-treated cells, no significant change in superoxide was detected, but according to our transcriptomic analysis, thousands of genes in CdSe/ZnS-treated cells became differentially expressed. Four significantly differentiated genes found, including FAF1, SDA1, DAN1, and TIR1, were validated by consistent results with RT-qPCR assays. Our transcriptome analysis led us to conclude that exposure of CdSe/ZnS-QDs on yeast significantly affected genes implicated in multiple cellular processes.

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Velusubhash, S., K. Kalirajan, S. Harikengaram, R. Vettumperumal, R. Murugesan, and A. Rajarajeswari. "Influence of Co-Dopant on Structural, Optical and Electrochemical Properties of Zinc Sulphide Quantum Dots." Volume 4,Issue 5,2018 4, no. 5 (August 5, 2018): 461–66. http://dx.doi.org/10.30799/jnst.143.18040501.

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In the present work, solution based simple chemical precipitation method has been employed to prepare undoped, cobalt (Co)-doped and cobalt, nickel (Co, Ni) co-doped ZnS quantum dots (QDs). The XRD pattern revealed that all samples displayed cubic zinc blende structure. The average crystallite size of as prepared ZnS QDs were found to be in 1.0 to 1.4 nm range. Surface morphological of synthesized samples were recorded and some distinction in morphological features between undoped, doped and co-doped ZnS QDs were noticed. EDX analysis confirms the presence of all corresponding elements in the samples. The blue-shift in the absorption spectra was observed. The optical band gap energy (Eg) for all the hybrid ZnS QDs samples were evaluated by using UV-Visible optical absorption spectral data. In PL analysis, emission band at 660 nm was found to be quenched as ZnS QDs interact with dopant and co-dopant. Electrochemical analysis was carried out by transition of photogenerated electrons in undoped, cobalt (Co)-doped and cobalt, nickel (Co, Ni) co-doped ZnS QDs modified glassy carbon electrodes. To authenticate the results of PL and electrochemical studies, photocatalytic behaviour of QDs were studied and positive impact of doping and co-doping process on photo degradation were noticed and discussed.

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Cheng, Ji-Chao, Ling-Yun Pan, Xiao-Li Huang, Yan-Ping Huang, Ying-Hui Wang, Shu-Ping Xu, Fang-Fei Li, Zhi-Wei Men, and Tian Cui. "Interparticle Spacing Effect among Quantum Dots with High-Pressure Regulation." Nanomaterials 11, no. 2 (January 27, 2021): 325. http://dx.doi.org/10.3390/nano11020325.

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In this paper, we explore whether interparticle spacing affects steady-state and transient-state optical properties by comparing close-packed CdSe/ZnS–quantum dots (QDs) and CdSe/ZnS–QDs dispersed in polymethyl methacrylate (PMMA). High–pressure is an effective physical means to adjust the interparticle spacing of QDs, which may artificially expand the application of QDs further. The results under high–pressure indicate that it is the reduced interparticle spacing rather than the enhanced quantum confinement effect with volume compression that has a stronger effect on exciton relaxation of CdSe/ZnS–QDs. This work is hoped to help us further understand the effect of interparticle spacing among QDs in various integrated environments.

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Hens, Basant, Jared Smothers, Husref Rizvanovic, Rishi Patel, Qihua Wu, and Kyoungtae Kim. "The Future of Anticancer Drugs: A Cytotoxicity Assessment Study of CdSe/ZnS Quantum Dots." Journal of Nanotheranostics 1, no. 1 (August 21, 2020): 19–38. http://dx.doi.org/10.3390/jnt1010003.

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Quantum dots (QDs), including CdSe/ZnS, are nanoparticles emitting various wavelengths of fluorescent light depending on their size. Fluorescence allows them to be exploited for in vivo sensing/imaging of cancer cells. Nevertheless, thorough assessments of the effects of these commonly used QDs on cell stability are essentially required prior to their full applications. To investigate the effects of Cd QDs on the growth of human cervical cancer cells (HeLa), we utilized a growth assay, a reactive oxygen species (ROS) assay, an apoptosis assay, and RNA-seq. The growth assay results showed significant proliferation inhibition of HeLa cells by CdSe/ZnS. We revealed that smaller green CdSe/ZnS exerts more toxic effects than slightly larger yellow CdSe/ZnS. There were no significant increases of ROSs under the treatment of Cd QDs, which is consistent with the notion that low concentration of Cd QDs does not cause significant production of ROSs. In addition, we found that Cd QDs induced late apoptosis. RNA-Seq-based transcriptome analysis revealed that the exposure to green Cd QDs significantly upregulated antiapoptotic, antiproliferative, and antitumorigenic functions. The transcriptome profile also noted the downregulation of pro-proliferation, mitochondrial respiratory chain, detoxification, and receptor-mediated endocytosis. Taken together, our findings provide evidence that green CdSe/ZnS can be an alternative anticancer drug. In addition, our transcriptome analysis provides new insights into alteration of physiological state induced by CdSe/ZnS QDs in HeLa cancer cells.

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Singh, Amandeep, and Manoj Sharma. "Optical and Morphological Studies of Doped Core Shell ZnS:Cu/ZnS Nanoparticles." Defect and Diffusion Forum 347 (December 2013): 247–54. http://dx.doi.org/10.4028/www.scientific.net/ddf.347.247.

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The paper presents some results of study based on applications of ZnS core shell quantum dots (QDs) doped with Cu. Keeping the luminous properties in focus we synthesized the core shell QDs by chemical precipitation route, resulting in formation of core@shell QDs with ZnS core doped with copper and ZnS shell on it, i.e. [ZnS:Cu@Zn. We focus the application of these particles in field of OLEDs (AMOLED) to address the performance deficiencies like varying brightness of the different wavelength emitting LEDs, called Green Window problem. Efforts have been done to address the problems by synthesizing highly luminescent green emitting copper doped ZnS, core@shell QDs. Further a monolayer of core shell quantum dots was deposited on ITO by spin coating for analyzing the photometric properties of the QDs.

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26

Amiri, Nasibeh Saeedzadeh, and Mohammad-Reza Milani-Hosseini. "Fabrication of an eco-friendly ratiometric fluorescence sensor-modified mesoporous-structured epitope-imprinted polymer for highly selective and sensitive determination of cytochrome c in biological samples." Analytical Methods 11, no. 46 (2019): 5919–28. http://dx.doi.org/10.1039/c8ay02773k.

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A ratiometric fluorescence sensor-modified mesoporous epitope-imprinted polymer was prepared for (QDs@SiO₂@EMSiO₂) for highly sensitive and selective determination of cytochrome c, using Cu-doped ZnS QDs and Mn-doped ZnS QDs as fluorescent dyes.

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Liu, Ying Fan, Wei Feng He, Guo Qing Wang, Shao Ming Fang, and Yu An Sun. "Synthesis of Highly Luminescent Glutathione-Capped CdTe-Mn/ZnS Quantum Dots." Advanced Materials Research 668 (March 2013): 691–95. http://dx.doi.org/10.4028/www.scientific.net/amr.668.691.

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A green synthetic route is reported for quickly synthesis of highly luminescent CdTe-Mn/ZnS quantum dots (QDs) in aqueous solution. Glutathione (GSH) was used as capping reagent and thioacetamide (TAA) as sulfur source for growth of ZnS shell on the CdTe-Mn QDs. At the optimum reaction conditions, the results indicate that the GSH-capped CdTe-Mn/ZnS QDs exhibit high fluorescence QYs and the best QY is 58%. These GSH-capped core-shell QDs exhibit excellent colloidal and photostability. This method is simple and environmentally friendly.

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Liu, Wei, Xian Lan Chen, La Shi Yang, Ju Cheng Zhang, Ping Yi, Ai Ping Fan, and He Ping Yan. "Photochemical Events during the Photosensitization of Hypocrellin A on ZnS Quantum Dots." Advanced Materials Research 581-582 (October 2012): 574–77. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.574.

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Hypocrellin A is organic dyes with more superior visible light performance, which has resistant tumor activity and becomes widely accepted. In this paper, acetone is used as solvent to extract, separate and purify the hypocrellin A. With ZnCl2 and Na2S as raw material, ZnS Quantum dots (QDs) were prepared by water-phase synthesis method under the role of the magnetic stirrer. Fluorescence detection results showed that the optimum pH of the ZnS QDs and HA solution close to neutral (6.86). The fluorescence quenching of hypocrellin A is most obvious as the ZnS QDs was added, because of the strong interaction was generated between HA and ZnS QDs, resulting in the fluorescence quenching.

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29

Cingarapu, Sreeram, Zhiqiang Yang, Christopher M. Sorensen, and Kenneth J. Klabunde. "Synthesis of CdSe/ZnS and CdTe/ZnS Quantum Dots: Refined Digestive Ripening." Journal of Nanomaterials 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/312087.

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We report synthesis of CdSe and CdTe quantum dots (QDs) from the bulk CdSe and CdTe material by evaporation/co-condensation using the solvated metal atom dispersion (SMAD) technique and refined digestive ripening. The outcomes of this new process are (1) the reduction of digestive ripening time by employing ligands (trioctylphosphine oxide (TOPO) and oleylamine (OA)) as capping agent as well as digestive ripening solvent, (2) ability to tune the photoluminescence (PL) from 410 nm to 670 nm, (3) demonstrate the ability of SMAD synthesis technique for other semiconductors (CdTe), (4) direct comparison of CdSe QDs growth with CdTe QDs growth based on digestive ripening times, and (5) enhanced PL quantum yield (QY) of CdSe QDs and CdTe QDs upon covering with a ZnS shell. Further, the merit of this synthesis is the use of bulk CdSe and CdTe as the starting materials, which avoids usage of toxic organometallic compounds, eliminates the hot injection procedure, and size selective precipitation processes. It also allows the possibility of scale up. These QDs were characterized by UV-vis, photoluminescence (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and powder XRD.

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Mao, Huibing, Ling Du, Ye Chen, Bo Li, Rong Huang, and Jiqing Wang. "Luminescence Emission Mediated by Surface Plasmon in the Semiconductor Quantum Dots." Nano 10, no. 01 (January 2015): 1550009. http://dx.doi.org/10.1142/s1793292015500095.

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The luminescence of the hybrid CdSe / ZnS QDs– Ag nanocrystals has a weak blue shift in comparison with the luminescence of the pure quantum dots (QDs). The luminescence of the CdSe / ZnS QDs only has a single exponential decay process, and the decay rates are almost same for different emission wavelengths. The luminescence of the hybrid CdSe / ZnS QDs– Ag nanocrystals structure has two decay processes: The first is a fast decay process, and then there is a slow decay process with nearly the same decay rate of the pure QDs. The fast decay process is due to the surface plasmon coupling and the coupling rate depends on the energy difference between the confined exciton in the QDs and the resonance energy of the Ag plasmon.

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Gromova, Yulia, Anastasiia Sokolova, Danil Kurshanov, Ivan Korsakov, Victoria Osipova, Sergei Cherevkov, Aliaksei Dubavik, et al. "Investigation of AgInS2/ZnS Quantum Dots by Magnetic Circular Dichroism Spectroscopy." Materials 12, no. 21 (November 4, 2019): 3616. http://dx.doi.org/10.3390/ma12213616.

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Over recent years, quantum dots (QDs) based on ternary metal dichalcogenides have attracted a lot of attention due to their unique properties and a range of potential applications. Here, we review the latest studies on the optical properties of AgInS2/ZnS QDs with emphasis on their theoretical modeling, and present our investigations of electronic transitions invisible in unstructured absorption spectra of AgInS2/ZnS QDs. The analysis of the absorption, photoluminescence excitation (PLE), and magnetic circular dichroism (MCD) spectra of hydrophobic and hydrophilic AgInS2/ZnS QDs of different sizes enables us to determine positions of electron transitions in these QDs. We demonstrate that the use of the second derivative of PLE spectra provides more unequivocal data on the position of the energy transitions compared with the second derivative of absorption spectra. Analysis of the MCD spectra reveals that the magnetic field induces energy level mixing in AgInS2/ZnS QDs in contrast to the traditional Cd-based QDs, where MCD is associated only with removing degeneracy of the excited energy level.

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32

Li, Gang, Li Hua Li, Liu Shuan Yang, and Jin Liang Huang. "Optical Properties of Water-Soluble Er-Doped ZnS Quantum Dots Synthesized by a Hydrothermal Process." Advanced Materials Research 800 (September 2013): 402–5. http://dx.doi.org/10.4028/www.scientific.net/amr.800.402.

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Er3+:ZnS quantum dots(QDs) were synthesized by hydrothermal process. The structure, morphology and luminescence properties were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. It was found that the Er3+:ZnS QDs are zinc blende structure with an average particle size of about 8 nm. In PL spectra, The broad peak of ZnS NCs located at 400nm was commonly assigned to sulfur vacancies. The intensity of exciting peak and emission peak at of Er3+:ZnS QDs decreased with doping concentration increasing.

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Irmania, Novi, Khalilalrahman Dehvari, and Jia-Yaw Chang. "Multifunctional MnCuInSe/ZnS quantum dots for bioimaging and photodynamic therapy." Journal of Biomaterials Applications 36, no. 9 (February 21, 2022): 1617–28. http://dx.doi.org/10.1177/08853282211068959.

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In this work, manganese (Mn)-doped CuInSe quantum dots (QDs) with a ZnS passivation layer (MnCuInSe/ZnS) have been synthesized via a one-pot microwave-assisted hydrothermal reaction using glutathione (GSH) as a stabilizer. The MnCuInSe/ZnS core-shell QDs combine magnetic resonance imaging (MRI), excitation-dependent red emission, and reactive oxygen radical generation functions, in which regulation of Mn2+ incorporation leads to synergistic imaging and therapeutic modalities. The MnCuInSe/ZnS QDs exhibit high colloidal and photochemical stability in simulated media and at different pH values. An r2/r1 ratio of 9.99 was calculated from MRI studies suggesting their potential application as dual-modal imaging agents. Based on in vitro tests on Hela, B16, and HepG2 cell lines, it is apparent that MnCuInSe/ZnS QDs impose no significant cytotoxicity in the dark, while they can efficiently generate singlet oxygen radicals for photodynamic therapy of cancers, killing more than 80% of B16 cells within 5 min of laser irradiation (671 nm, 1 W cm−2). Furthermore, in vitro fluorescence imaging and cellular internalization of QDs are examined to visualize cellular uptake and in situ ROS generation. Therefore, this research exemplifies a new set of multifunctional chalcogenide QDs for theranostic applications.

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Karim, Md Rezaul, Mesut Balaban, and Hilmi Ünlü. "Strain Effects on the Band Gap and Diameter of CdSe Core and CdSe/ZnS Core/Shell Quantum Dots at Any Temperature." Advances in Materials Science and Engineering 2019 (September 22, 2019): 1–10. http://dx.doi.org/10.1155/2019/3764395.

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We present the results of an experimental study about strain effects on the core band gap and diameter of spherical bare CdSe core and CdSe/ZnS core/shell quantum dots (QDs) synthesized by using a colloidal technique at varying temperatures. Structural characterizations were made by using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) techniques. Optical characterizations were made by using UV-Vis absorption and fluorescence emission spectroscopies. The XRD analysis suggests that the synthesized bare CdSe core and CdSe/ZnS core/shell QDs have zinc blende crystal structure. HRTEM results indicate that the CdSe core and CdSe/ZnS QDs have average particle sizes about 3.50 nm and 4.84 nm, respectively. Furthermore, compressive strain causes an increase (decrease) in the core band gap (diameter) of spherical CdSe/ZnS core/shell QDs at any temperature. An elastic strain-modified effective mass approximation (EMA) predicts that there is a parabolic decrease (increase) in the core band gap (diameter) of QDs with temperature. The diameter of spherical bare CdSe core and CdSe/ZnS core/shell QDs calculated by using the strain-modified EMA, with core band gap extracted from absorption spectra, are in excellent agreement with the HRTEM data.

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Xu, Shi Chao, Cui Cui Yao, Ji Mei Zhang, Zhao Dai, Guo Zheng, Bo Sun, Shu Qing Sun, Qing Han, Fei Hu, and Hong Ming Zhou. "Synthesis and Characterization of the Core-Shell CdTe/ZnS Quantum Dots." Advanced Materials Research 60-61 (January 2009): 165–69. http://dx.doi.org/10.4028/www.scientific.net/amr.60-61.165.

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Core-shell quantum dots are colloidal particles consisting of a semiconductor core and a shell material as an outer coating layer. It can be utilized to develop sensitive methods for the detection of specific biological entities, such as microbial species, their transcription products, and single genes etc. The goal of current research is to synthesize CdTe and core-shell CdTe/ZnS quantum dots (QDs) with an improved process, and to investigate their properties. Well-dispersed CdTe core was prepared in aqueous phase with using 3-mercaptopropionic acid (MPA) as stabilizer under conditions of pH 9.1, temperature of 100 °C, refluxing for 6h, and mol ratio of Cd2+/Te2-/MPA is 1:0.5:2.4. Average size of 8 nm CdTe core was conformed via transmission electron microscopy (TEM). Core-shell CdTe/ZnS QDs were then synthesized to improve the optical properties and biocompatibility of CdTe core. Various conditions were researched to obtain the core-shell QDs with the best optical properties, such as quantum yields, fluorescence intensity etc. The results indicated that the core-shell qualified CdTe/ZnS was prepared under conditions of pH 9.0, temperature of 45 °C, refluxing for 1h, and mol ratio of CdTe/S2-/Zn2+ is 4/1/1. CdTe/ZnS with average size of 10 nm were achieved and conformed via TEM. Moreover, red shift of a maximum emission wavelength from 547 nm of CdTe to 587 of CdTe/ZnS was observed via fluorescence spectrum (FS), which inferred the growth of QDs and formation of ZnS shells. The achieved ZnS shell make CdTe core less toxic and more biocompatible, it will be useful in biological labeling, diagnostic process and biosensing system based on fluorescence resonance energy transition (FRET).

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36

Cheng, Xunqiang, Mingming Liu, Qinggang Zhang, Mengda He, Xinrong Liao, Qun Wan, Wenji Zhan, Long Kong, and Liang Li. "A Novel Strategy to Enhance the Photostability of InP/ZnSe/ZnS Quantum Dots with Zr Doping." Nanomaterials 12, no. 22 (November 17, 2022): 4044. http://dx.doi.org/10.3390/nano12224044.

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Plentiful research of InP semiconductor quantum dots (QDs) has been launched over the past few decades for their excellent photoluminescence properties and environmentally friendly characteristics in various applications. However, InP QDs show inferior photostability because they are extremely sensitive to the ambient environment. In this study, we propose a novel method to enhance the photostability of InP/ZnSe/ZnS QDs by doping zirconium into the ZnS layer. We certify that Zr can be oxidized to Zr oxides, which can prevent the QDs from suffering oxidation during light irradiation. The InP/ZnSe/ZnS:Zr QDs maintained 78% of the original photoluminescence quantum yields without significant photodegradation under the irradiation of LED light (450 nm, 3.0 W power intensity) for 14 h, while conventional InP/ZnSe/ZnS QDs dramatically decreased to 29%.

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Torimoto, Tsukasa, Tatsuya Mori, Tatsuya Kameyama, Taro Uematsu, and Susumu Kuwabata. "(Invited, Digital Presentation) Controlling the Energy Structure of Ag(In,Ga)S Quantum Dots for Photocatalytic H₂ Evolution." ECS Meeting Abstracts MA2022-01, no. 36 (July 7, 2022): 1576. http://dx.doi.org/10.1149/ma2022-01361576mtgabs.

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Quantum dots (QDs) composed of group I-III-VI semiconductors, such as CuInS2 and AgInS2, exhibit unique size- and composition-dependent physicochemical properties different from bulk materials due to the quantum size effect. Furthermore, these QDs have attracted intense attention for developing highly efficient solar energy conversion systems, because of the less toxicity and the large absorption coefficients in visible and near-IR regions. Recently we have successfully prepared alloy QDs composed of ZnAgInS or ZnAgInSe semiconductors, the Eg of which was tunable in the visible or near-IR wavelength regions, respectively [1, 2]. Their photocatalytic H2 evolution activity was controlled by the chemical composition and size of QDs. On the other hand, the Eg of bulk I-III-VI semiconductors can be controlled by alloying different metal cations of group III elements. Thus, in this study, we prepare spherical QDs composed of less-toxic AgIn(1-x)GaxS2 (AIGS(x)) alloy semiconductor and report their composition-dependent photocatalytic activity for H2 evolution under visible light irradiation. AIGS(x) QDs with different x values were synthesized by thermal decomposition of Ag(OAc), In(acac)3, Ga(acac)3, and S powders in a mixture solution of oleylamine and dodecanethiol. The chemical composition of resulting QDs, that is, x value, could be controlled by varying the Ga/(In+Ga) ratio in preparation. Thus-obtained AIGS QDs were surface-coated with ZnS shell of various thickness, resulting in the formation of core-shell-structured QDs, AIGS(x)@ZnS. Finally, the ligands modified on the nanocrystal surface were changed from dodecanethiol to mercaptopropionic acid to improve the dispersibility of QDs in an aqueous solution. The obtained AIGS QDs had a spherical shape with size of ca. 4 nm. The ZnS thickness of AIGS(x)@ZnS was varied from 0 to ca. 2 nm. The photocatalytic activity of AIGS(x)@ZnS QDs was investigated for H2 evolution as a model reaction. The irradiation to AIGS(x)@ZnS QDs suspended in an aqueous solution containing Na2S as a hole scavenger was carried out using Xe lamp light (λ> 350 nm). With the elapse of light irradiation, the amount of H2 evolved linearly increased, regardless of the composition of AIGS core or the ZnS shell thickness. The H2 evolution rate was remarkably dependent on the composition of AIGS core: A volcano-type dependence was observed between the H2 evolution rate and the Ga fraction. The highest photocatalytic activity was obtained for AIGS(x)@ZnS QDs with x=0.6 and the ZnS shell thickness of ca. 2 nm. This behavior can be explained by the changes in the stability of AIGS core in aqueous solutions, the conduction band minimum level of QDs, and the amount of photon absorption. References Kameyama, T. Takahashi, T. Machida, Y. Kamiya, T. Yamamoto, S. Kuwabata, and T. Torimoto, J. Phys. Chem. C, 2015, 119, 24740-24749. P.-Y. Hsieh, T. Kameyama, T. Takiyama, T. Yamamoto, Y.-J. Hsu and T. Torimoto, J. Mater. Chem. A 2020 , 8, 13142-13149.

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Heyne, Benjamin, Kristin Arlt, André Geßner, Alexander F. Richter, Markus Döblinger, Jochen Feldmann, Andreas Taubert, and Armin Wedel. "Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media." Nanomaterials 10, no. 9 (September 17, 2020): 1858. http://dx.doi.org/10.3390/nano10091858.

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Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%.

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Zhang, Xiaosong, Lan Li, Ting Ji, RongWei Xuan, JianPing Xu, and Xiaojuan Liu. "Correlated Color Temperature Tunable White Electroluminescence from Cadmium-Free ZnS Quantum Dots." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3724–28. http://dx.doi.org/10.1166/jnn.2016.11891.

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We propose correlated color temperature tunable white light-emitting from different sizes cadmiumfree quantum dots (QDs) without organic ligand-modulation. A size series of free-standing ZnS QDs were prepared by coprecipitation method. Experimental results show that the broad electroluminescences (EL) spectra from all samples cover almost the entire visible region and the electroluminescence peak is significantly redshifted from 489 to 580 nm with ZnS QDs sizes increasing from 1.1 to 4 nm. Moreover, the chromaticity coordinates calculated from EL spectra are (0.27, 0.36), (0.36, 0.42) and (0.42, 0.46) for QDs with average sizes 1.1, 2 and 4 nm drived at 15 V respectively, correspondingly, white EL spectra with a continuously tunable color changes from bluish white (CCT 12400 K) to yellowish white (CCT 3700 K). The differences between the photoluminescence (PL) and EL spectra were observed. Furthermore, the comparison between EL and PL spectra and active defect-levels of ZnS QDs with various sizes are discussed to understand the mechanism of the tunable spectra. The results offer that a convenience method to obtain tunable EL spectra in white color from ZnS QDs defects by controlling the size of the QDs.

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Amani-Ghadim, Ali Reza, Fatemeh Khodam, and Mir Saeed Seyed Dorraji. "ZnS quantum dot intercalated layered double hydroxide semiconductors for solar water splitting and organic pollutant degradation." Journal of Materials Chemistry A 7, no. 18 (2019): 11408–22. http://dx.doi.org/10.1039/c9ta01412h.

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M^IIZnAl-LDH/ZnS QD (M^II = Co or Mn) nanocomposites were synthesized by assembling oppositely charged 2D LDH layers and ZnS QDs. The M^IIZnAl-LDH/ZnS QDs exhibited enhanced visible light harvesting ability, considerable visible light photocatalytic activity and photostability.

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Zhu, Huaping, Michael Z. Hu, Lei Shao, Kui Yu, Reza Dabestani, Md Badruz Zaman, and Shijun Liao. "Synthesis and Optical Properties of Thiol Functionalized CdSe/ZnS (Core/Shell) Quantum Dots by Ligand Exchange." Journal of Nanomaterials 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/324972.

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The colloidal photoluminescent quantum dots (QDs) of CdSe (core) and CdSe/ZnS (core/shell) were synthesized at different temperatures with different growth periods. Optical properties (i.e., UV/Vis spectra and photoluminescent emission spectra) of the resulting QDs were investigated. The shell-protected CdSe/ZnS QDs exhibited higher photoluminescent (PL) efficiency and stability than their corresponding CdSe core QDs. Ligand exchange with various thiol molecules was performed to replace the initial surface passivation ligands, that is, trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP), and the optical properties of the surface-modified QDs were studied. The thiol ligand molecules in this study included 1,4-benzenedimethanethiol, 1,16-hexadecanedithiol, 1,11-undecanedithiol, biphenyl-4,4′-dithiol, 11-mercapto-1-undecanol, and 1,8-octanedithiol. After the thiol functionalization, the CdSe/ZnS QDs exhibited significantly enhanced PL efficiency and storage stability. Besides surface passivation effect, such enhanced performance of thiol-functionalized QDs could be due to cross-linked assembly formation of dimer/trimer clusters, in which QDs are linked by dithiol molecules. Furthermore, effects of ligand concentration, type of ligand, and heating on the thiol stabilization of QDs were also discussed.

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Abd. Rahman, Samsulida, Nurhayati Ariffin, Nor Azah Yusof, Jaafar Abdullah, Zuhana Ahmad Zubir, Nik Mohd Azmi Nik Abdul Aziz, Nur Ellina Azmi, Hamidah Sidek, and Noor Izaanin Ramli. "Synthesis and Surface Modification of Biocompatible Water Soluble Core-Shell Quantum Dots." Advanced Materials Research 879 (January 2014): 184–90. http://dx.doi.org/10.4028/www.scientific.net/amr.879.184.

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In this study, the applications of CdSe/ZnS quantum dots (QDs) and its role in advanced sensings has been explored. The CdSe/ZnS was synthesized by using hot injection method with the shell ZnS layer was made using successive ionic layer adsorption and reaction (SILAR) method. The morphology of the CdSe/ZnS QDs was studied using Transmission Electron Microscope (TEM) and the average particle size was in 10-12 nm range. The prepared QDs were optically characterized using spectrofluorescence and strong emission was observed at 620 nm. Comparison of the fluorescence emissions of CdSe/ZnS capped with various capping ligands such as L-cysteine, thioglycolic acid (TGA), mercaptopropionic acid (MPA), mercaptosuccinic acid (MSA) and mercaptoundecanoic acid (MUA) were studied. The CdSe/ZnS capped with TGA gave the strongest fluorescence emission compared to others.

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Liu, Wenyan, Yu Zhang, Cheng Ruan, Dan Wang, Tieqiang Zhang, Yi Feng, Wenzhu Gao, et al. "ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect." Journal of Nanomaterials 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/298614.

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The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0 lm/W for red, 47.1 lm/W for yellow, and 62.4 lm/W for green LEDs at 2.6 V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to the low emission temperature coefficients of 0.022, 0.050, and 0.068 nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs.

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Abib, Mukerem Helil, Yajing Chang, Xudong Yao, Guopeng Li, Dabin Yu, and Yang Jiang. "Scale Synthesis of Environment Friendly CIZS/ZnS Core/Shell Quantum Dots for High Color Quality White LEDs." Nano 12, no. 02 (February 2017): 1750014. http://dx.doi.org/10.1142/s179329201750014x.

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Environment-friendly CuInZnS (CIZS) core and CuInZnS/ZnS (CIZS/ZnS) core/shell quantum dots (QDs) were synthesized via a facile solution-phase method. Different methods certified that the ZnS shell was successfully coated on CIZS core. The coating of ZnS shell would lead to the quantum yield increase and optical spectra blue shifted. Furthermore, the CIZS and CIZS/ZnS had a long PL lifetime of 257.3[Formula: see text]ns and 411.6[Formula: see text]ns, respectively. Finally, the CIZS/ZnS QDs powder with yellow emission was used to compose white light emitting diodes (WLED) on blue LED chip. The WLED had a [Formula: see text] of 80, [Formula: see text] of 4793[Formula: see text]K, and CIE coordinates of (0.346, 0.321) under 20[Formula: see text]mA current, and had a bright warm white emission, which indicated the promising potential of the CIZS/ZnS QDs in the optoelectronics.

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Skobeeva, V. M., V. A. Smyntyna, M. I. Kiose, and N. V. Malushin. "EVOLUTION OF LUMINESCENT PROPERTIES DURING STORAGE CdS QDs IN AIR." Photoelectronics, no. 30 (December 24, 2021): 21–26. http://dx.doi.org/10.18524/0235-2435.2021.30.262798.

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This paper presents the results of a study the CdS QDs and nanostructures of CdS / ZnS QDs obtained by the sol - gel technology in an aqueous solution of gelatin and the effect of storage on their luminescence. An increase in the luminescence intensity was found after storage the samples in air. It is revealed that the highest growth factor of the luminescence intensity is observed in CdS QDs without a shell. A mechanism has been formulated that affects the luminescent properties of CdS QDs and nanostructures of CdS / ZnS QDs during storage.

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Kim, Yi su, Yonghee Lee, Youngsun Kim, Donghyuk Kim, Hyung Seok Choi, Jae Chul Park, Yoon Sung Nam, and Duk Young Jeon. "Synthesis of efficient near-infrared-emitting CuInS2/ZnS quantum dots by inhibiting cation-exchange for bio application." RSC Advances 7, no. 18 (2017): 10675–82. http://dx.doi.org/10.1039/c6ra27045j.

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Near-infrared (NIR)-emitting CuInS₂(CIS)/ZnS quantum dots (QDs) were synthesized, and we investigated temperature-dependence of cationic exchange during ZnS shell growth. The obtained QDs were transformed to nanocapsules for bio-application.

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Zhao, Mengjie, Shuai Ye, Xiao Peng, Jun Song, and Junle Qu. "Green emitted CdSe@ZnS quantum dots for FLIM and STED imaging applications." Journal of Innovative Optical Health Sciences 12, no. 05 (September 2019): 1940003. http://dx.doi.org/10.1142/s1793545819400030.

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Inorganic quantum dots (QDs) have excellent optical properties, such as high fluorescence intensity, excellent photostability and tunable emission wavelength, etc., facilitating them to be used as labels and probes for bioimaging. In this study, CdSe@ZnS QDs are used as probes for Fluorescence lifetime imaging microscope (FLIM) and stimulated emission depletion (STED) nanoscopy imaging. The emission peak of CdSe@ZnS QDs centered at 526[Formula: see text]nm with a narrow width of 19[Formula: see text]nm and the photoluminescence quantum yield (PLQY) was 64%. The QDs presented excellent anti-photobleaching property which can be irradiated for 400[Formula: see text]min by STED laser with 39.8[Formula: see text]mW. The lateral resolution of 42.0[Formula: see text]nm is demonstrated for single QDs under STED laser (27.5[Formula: see text]mW) irradiation. Furthermore, the CdSe@ZnS QDs were for the first time used to successfully label the lysosomes of living HeLa cells and 81.5[Formula: see text]nm lateral resolution is obtained indicating the available super-resolution applications in living cells for inorganic QD probes. Meanwhile, Eca-109 cells labeled with the CdSe@ZnS QDs was observed with FLIM, and their fluorescence lifetime was around 3.1[Formula: see text]ns, consistent with the in vitro value, suggesting that the QDs could act as a satisfactory probe in further FLIM-STED experiments.

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Ünlü, Hilmi. "A thermoelastic model for strain effects on bandgaps and band offsets in heterostructure core/shell quantum dots." European Physical Journal Applied Physics 86, no. 3 (June 2019): 30401. http://dx.doi.org/10.1051/epjap/2019180350.

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A thermoelastic model is proposed to determine elastic strain effects on electronic properties of spherical Type I and Type II heterostructure core/shell quantum dots (QDs) as a function of dimensions of constituent semiconductors at any temperature. Proposed model takes into account the difference between lattice constants, linear expansion coefficients and anisotropy of elastic moduli (Young's modulus and Poisson's ratio) of constituent semiconductors, respectively. In analogous to lattice mismatch, we introduce so called the elastic anisotropy mismatch in heterostructures. Compressive strain acting on core (shell) side of heterointerfaces in CdSe/CdS, CdSe/ZnS, and ZnSe/ZnS QDs increases (decreases) as shell diameter is increased, which causes increase (decrease) in core bandgap as sell (core) diameter is increased in these nanostructures. Furthermore, there is a parabolic increase in conduction band offsets and core bandgaps in CdSe/CdS, CdSe/ZnS, and ZnSe/ZnS QDs and decrease in conduction band offset and core bandgap of ZnSe/CdS QD as core (shell) diameter increases for fixed shell (core) diameter. Comparison shows that using isotropic elastic moduli in determining band offsets and core band gaps gives better agreement with experiment than anisotropic elastic moduli for core bandgaps of CdSe/CdS, CdSe/ZnS, ZnSe/ZnS, and ZnSe/CdS core/shell QDs. Furthermore, we also show that the strain-modified two band effective mass approximation can be used to determine band offsets by using measured core band gaps in core/shell heterostructure QDs with Type II interface band alignment. Excellent agreement between predicted and measured core bandgaps in CdSe and ZnSe based core/shell QDs suggests that proposed model can be a good design tool for process simulation of core/shell heterostructure QDs.

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Tang, Luping, Chen Liao, Yingqing Guo, and Yangyang Zhang. "Controllable Preparation of Ag-SiO2 Composite Nanoparticles and Their Applications in Fluorescence Enhancement." Materials 16, no. 1 (December 26, 2022): 201. http://dx.doi.org/10.3390/ma16010201.

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Metal nanoparticles have attracted a great deal of interest due to their unique properties of surface plasmon resonance. Metal nanoparticles can enhance the fluorescence emission intensity of quantum dots (QDs) through the local surface plasmon resonance effect, which is mainly determined by the distance between them. Therefore, it is very important to achieve controllable distance between metal and QDs, and study fluorescence enhancement. In this work, the controllable adjustment of the distance between metal nanoparticles and QDs was successfully realized by controlling the thickness of the SiO2 shell of Ag@SiO2 nanoparticles. Firstly, Ag nanoparticles with uniform size distribution and relatively high concentration were prepared, and then the thickness of the SiO2 shell was controlled by controlling the amount of tetra-ethyl orthosilicate (TEOS) in the hydrolysis of TEOS reaction. (3-aminopropyl) triethoxysilane (APS) was used to connect CdS/ZnS QDs with Ag@SiO2 nanoparticles to form Ag@SiO2@CdS/ZnS QD composite nanoparticles. The fluorescence spectra shows that the fluorescence intensity of the Ag@SiO2@CdS/ZnS QD composite nanoparticles is significantly enhanced. Photoexcitation spectra and fluorescence spectra of CdS/ZnS QD and Ag@SiO2@CdS/ZnS QD composite nanoparticles, measured under different energy excitation conditions, indicate that the existence of Ag nanoparticles can enhance the fluorescence intensity of CdS/ZnS QDs. Finally, a further physical mechanism of fluorescence enhancement is revealed.

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Li, Li, Tingting Chen, Zhiwen Yang, Yajing Chen, Dongmeng Liu, Huiyu Xiao, Maixian Liu, et al. "Nephrotoxicity Evaluation of Indium Phosphide Quantum Dots with Different Surface Modifications in BALB/c Mice." International Journal of Molecular Sciences 21, no. 19 (September 27, 2020): 7137. http://dx.doi.org/10.3390/ijms21197137.

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InP QDs have shown a great potential as cadmium-free QDs alternatives in biomedical applications. It is essential to understand the biological fate and toxicity of InP QDs. In this study, we investigated the in vivo renal toxicity of InP/ZnS QDs terminated with different functional groups—hydroxyl (hQDs), amino (aQDs) and carboxyl (cQDs). After a single intravenous injection into BALB/c mice, blood biochemistry, QDs distribution, histopathology, inflammatory response, oxidative stress and apoptosis genes were evaluated at different predetermined times. The results showed fluorescent signals from QDs could be detected in kidneys during the observation period. No obvious changes were observed in histopathological detection or biochemistry parameters. Inflammatory response and oxidative stress were found in the renal tissues of mice exposed to the three kinds of QDs. A significant increase of KIM-1 expression was observed in hQDs and aQDs groups, suggesting hQDs and aQDs could cause renal involvement. Apoptosis-related genes (Bax, Caspase 3, 7 and 9) were up-regulated in hQDs and aQDs groups. The above results suggested InP/ZnS QDs with different surface chemical properties would cause different biological behaviors and molecular actions in vivo. The surface chemical properties of QDs should be fully considered in the design of InP/ZnS QDs for biomedical applications.

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Journal articles on the topic 'ZnS QDs'

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