scholarly journals Graphene Quantum Dots-Modified Ternary ZnCdS Semiconductor for Enhancing Photoelectric Properties

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Zicong Jiang ◽  
Yun Lei ◽  
Mingzhen Zhang ◽  
Zheng Zhang ◽  
Zhong Ouyang
Keyword(s):  
Quantum Dots ◽  
Photoelectric Property ◽  
Graphene Quantum Dots ◽  
Photocurrent Density ◽  
Solvothermal Route ◽  
Photoelectric Properties ◽  
Good Lattice

A series of graphene quantum dots-modified ZnCdS (ZnCdS/G) composites with different contents of graphene quantum dots (GQDs) were prepared by a solvothermal route and characterized via various measurements. GQDs have a type graphene height of 2 nm and exhibit an excitation-dependent PL behavior. GQDs-modified ZnCdS composites present good lattice fingers that can be assigned to the (110) plane of GQDs and (112) plane of ZnCdS. The effect of different GQDs contents on the photoelectric property of ZnCdS was investigated. The results show that the photocurrent density of ZnCdS/G first increases and achieves a maximum of 11.4 μA/cm2 with the addition of 0.06 wt% and then decreases as the GQDs content changes from 0.06 wt% to 0.12 wt%. Photocurrent counts as a function of time present a decrease of 10% and remains stable after 1600 s.

scholarly journals Graphene Quantum Dots Decorated Al-doped ZnS for Improved Photoelectric Performance

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1452 ◽  
Author(s):  
Zheng Zhang ◽  
Yun Lei ◽  
Liyang Zhao ◽  
Zicong Jiang ◽  
Zhong Ouyang
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Photogenerated Electron ◽  
Photocurrent Density ◽  
Spectroscopic Techniques ◽  
Solvothermal Process ◽  
Al Doping ◽  
Photogenerated Electrons ◽  
Photoelectric Performance ◽  
Conducting Materials

Graphene quantum dots (GQDs) decorated Al-doped ZnS composites were prepared using the solvothermal process, and the hydrothermal method was used to prepare GQDs. Various spectroscopic techniques were used to characterize the products, and the results show that Al-ZnS attached GQD composites present lattice fringes that can be assigned to ZnS and GQDs, respectively. The absorption peaks of Al-ZnS/GQDs are red-shifted because of the doping of aluminum and the incorporation of GQDs. The luminescence intensity of Al-ZnS/GQDs shows a downward trend with the addition of GQDs. As the GQD content changes from 0.6 wt % to 1.8 wt %, the photocurrent density achieves a maximum at the addition of 1.2 wt %. The photocurrent of Al-ZnS/GQDs composites are about 700% and 200% of pure ZnS and Al-ZnS, respectively. The results indicate that Al doping can reduce the energy bandgap of ZnS and produce more photogenerated electrons. The photogenerated electrons from Al-ZnS can be extracted and transferred to GQDs, which act as conducting materials to decrease the recombination rate and improve the photogenerated electron-transfer.

scholarly journals Inhibition of Photoconversion Activity in Self-Assembled ZnO-Graphene Quantum Dots Aggregated by 4-Aminophenol Used as a Linker

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2802 ◽  
Author(s):  
Kyu Seung Lee ◽  
Young Jae Park ◽  
Jaeho Shim ◽  
Guh-Hwan Lim ◽  
Sang-Youp Yim ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Visible Region ◽  
Photocurrent Density ◽  
Solvothermal Process ◽  
High Contribution ◽  
Photoluminescence Lifetime ◽  
Pec Cells ◽  
Calculated Average ◽  
Light Scattering Effect

The aggregation of zinc oxide nanoparticles leads to an increased absorbance in the ultraviolet-visible region by an induced light scattering effect. Herein, we demonstrate the inhibition of photoconversion activity in ZnO-graphene core-shell quantum dots (QD) (ZGQDs) agglomerated by 4-aminophenol (4-AP) used as a linker. The ZnO-graphene quantum dots (QD) aggregates (ZGAs) were synthesized using a facile solvothermal process. The ZGAs revealed an increased absorbance in the wavelengths between 350 and 750 nm as compared with the ZGQDs. Against expectation, the calculated average photoluminescence lifetime of ZGAs was 7.37 ns, which was 4.65 ns longer than that of ZGQDs and was mainly due to the high contribution of a slow (τ2, τ3) component by trapped carriers in the functional groups of graphene shells and 4-AP. The photoelectrochemical (PEC) cells and photodetectors (PDs) were fabricated to investigate the influence of ZGAs on the photoconversion activity. The photocurrent density of PEC cells with ZGAs was obtained as 0.04 mA/cm2 at 0.6 V, which was approximately 3.25 times lower than that of the ZGQDs. The rate constant value of the photodegradation value of rhodamine B was also decreased by around 1.4 times. Furthermore, the photoresponsivity of the PDs with ZGAs (1.54 μA·mW−1) was about 2.5 times as low as that of the PDs with ZGQDs (3.85 μA·mW−1). Consequently, it suggests that the device performances could be degraded by the inhibition phenomenon of the photoconversion activity in the ZGAs due to an increase of trap sites.

Synthesis of graphene quantum dots doped CdS composites for photoelectric properties

2019 ◽  
Vol 6 (12) ◽  
pp. 125608 ◽  
Author(s):  
Yun Lei ◽  
Yuanyuan Lin ◽  
Jinyang Wang ◽  
Zheng Zhang ◽  
Zicong Jiang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Photoelectric Properties

Photoelectric properties of SnO2 decorated by graphene quantum dots

2019 ◽  
Vol 102 ◽  
pp. 104582 ◽  
Author(s):  
Yun Lei ◽  
Jiaxin Hu ◽  
Zheng Zhang ◽  
Zhong Ouyang ◽  
Zicong Jiang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Photoelectric Properties

Graphene Quantum Dots Incorporated SnO2 Composites with Improved Photoelectric Properties

2019 ◽  
Vol 11 (2) ◽  
pp. 175-181
Author(s):  
Xin Bing ◽  
Chaopeng Kong ◽  
Zheng Zhang ◽  
Yun Lei
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Photoelectric Properties

S, N co-doped graphene quantum dots decorated CdSe for enhanced photoelectric properties

2019 ◽  
Vol 31 (9) ◽  
pp. 095710 ◽  
Author(s):  
Zhong Ouyang ◽  
Yun Lei ◽  
Liqun Luo ◽  
Zicong Jiang ◽  
Jiaxin Hu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Photoelectric Properties ◽  
Doped Graphene ◽  
Co Doped

scholarly journals Preparation of Graphene Quantum Dots and Their Application in Cell Imaging

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Jie Zhang ◽  
Yong-qiang Ma ◽  
Na Li ◽  
Jing-li Zhu ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Reaction Time ◽  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Laser Scanning ◽  
Cell Imaging ◽  
Graphene Quantum Dots ◽  
Dimethyl Formamide ◽  
Experimental Conditions ◽  
Solvothermal Route

Objective. This study aims to increase the fluorescence quantum yield by improving the conditions of preparing graphene quantum dots (GQDs) through the solvothermal route and observe the GQDs performance in imaging oral squamous cells.Methodology. The following experimental conditions of GQDs preparation through the solvothermal route were improved: graphene oxide (GO)/N-N dimethyl formamide (DMF) ratio, filling percentage, and reaction time. A fluorescence spectrophotometer was used to measure photoluminescence, and the peak values were compared. Methylthiazolyldiphenyl-tetrazolium (MTT) bromide was used to detect the cytotoxicity of GQDs, which was compared with that of cadmium telluride quantum dots (CdTe QDs). GQDs were cultured with tongue cancer cells. After the coculture, a laser scanning confocal microscope (LSCM) was used to observe cell imaging.Results. The optimal conditions of GQD preparation through the solvothermal route included the following: 10 mg/mL GO/DMF ratio, 80% filling percentage, 12 h reaction time, and 17.4% fluorescence quantum yield. As the cell concentration increased, the GQD and CdTe QD groups exhibited a decreasing cell survival rate, with the decrease in the CdTe QD group being more significant. The LSCM observations showed bright green fluorescence images.Conclusion. The improved experimental conditions increased the fluorescence quantum yield of GQDs. In this study, the prepared GQDs exhibited low cytotoxicity level and satisfactory cell imaging performance.

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