scholarly journals Graphene Quantum Dots Open Up New Prospects for Interfacial Modifying in Graphene/Silicon Schottky Barrier Solar Cell

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chao Geng ◽  
Xiuhua Chen ◽  
Shaoyuan Li ◽  
Zhao Ding ◽  
Wenhui Ma ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Schottky Barrier ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
Separation Processes ◽  
Band Bending ◽  
Carrier Recombination ◽  
Photovoltaic Applications ◽  
Graphene Oxide Quantum Dots

Graphene/silicon (Gr/Si) Schottky barrier solar cells (SBSCs) are attractive for harvesting solar energy and have been gaining grounds for its low-cost solution-processing. The interfacial barrier between graphene and silicon facilitates the reducing excessive carrier recombination while accelerating the separation processes of photo-generated carriers at the interface, which empowers the performance of Gr/Si SBSCs. However, the difficulty to control the interface thickness prevents its application. Here, we introduce the graphene oxide quantum dots (GOQDs) as a unique interfacial modulation species with tunable thickness by controlling the GOQDs particle size. The power conversion efficiency (PCE) of 13.67% for Gr/Si-based SBSC with outstanding stability in the air is obtained with the optimal barrier thickness (26 nm) and particle size (4.15 nm) of GOQDs. The GOQDs in Gr/Si-based SBSCs provide the extra band bending which further enhances the PCE for its photovoltaic applications.

scholarly journals Graphene Quantum Dots with High Yield and High Quality Synthesized from Low Cost Precursor of Aphanitic Graphite

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 375 ◽  
Author(s):  
Shuling Shen ◽  
Junjie Wang ◽  
Zhujun Wu ◽  
Zheng Du ◽  
Zhihong Tang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
High Strength ◽  
High Yield ◽  
Average Thickness ◽  
High Quality ◽  
Graphene Oxide Quantum Dots ◽  
2D Nanosheets ◽  
First Time

It is difficult to keep the balance of high quality and high yield for graphene quantum dots (GQDs). Because the quality is uncontrollable during cutting large 2D nanosheets to small 0D nanodots by top-down methods and the yield is low for GQDs with high quality obtained from bottom-up strategy. Here, aphanitic graphite (AG), a low-cost graphite contains a large amount of small graphite nanocrystals with size of about 10 nm is used as the precursor of graphene oxide quantum dots (GO-QDs) for the first time. GO-QDs with high yield and high quality were successfully obtained directly by liquid phase exfoliating AG without high strength cutting. The yield of these GO-QDs can reach up to 40 wt. %, much higher than that obtained from flake graphite (FG) precursor (less than 10 wt. %). The size of GO-QDs can be controlled in 2–10 nm. The average thickness of GO-QDs is about 3 nm, less than 3 layer of graphene sheet. Graphene quantum dots (GQDs) with different surface properties can be easily obtained by simple hydrothermal treatment of GO-QDs, which can be used as highly efficient fluorescent probe. Developing AG as precursor for GQDs offers a way to produce GQDs in a low-cost, highly effective and scalable manner.

scholarly journals High yield synthesis of graphene quantum dots from biomass waste as a highly selective probe for Fe3+ sensing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aumber Abbas ◽  
Tanveer A. Tabish ◽  
Steve J. Bull ◽  
Tuti Mariana Lim ◽  
Anh N. Phan
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
Cost Effective ◽  
Renewable Resource ◽  
Microwave Treatment ◽  
High Yield ◽  
Biomass Waste ◽  
Practical Applications

AbstractGraphene quantum dots (GQDs), a novel type of zero-dimensional fluorescent materials, have gained considerable attention owing to their unique optical properties, size and quantum confinement. However, their high cost and low yield remain open challenges for practical applications. In this work, a low cost, green and renewable biomass resource is utilised for the high yield synthesis of GQDs via microwave treatment. The synthesis approach involves oxidative cutting of short range ordered carbon derived from pyrolysis of biomass waste. The GQDs are successfully synthesised with a high yield of over 84%, the highest value reported to date for biomass derived GQDs. As prepared GQDs are highly hydrophilic and exhibit unique excitation independent photoluminescence emission, attributed to their single-emission fluorescence centre. As prepared GQDs are further modified by simple hydrothermal treatment and exhibit pronounced optical properties with a high quantum yield of 0.23. These modified GQDs are used for the highly selective and sensitive sensing of ferric ions (Fe3+). A sensitive sensor is prepared for the selective detection of Fe3+ ions with a detection limit of as low as 2.5 × 10–6 M. The utilisation of renewable resource along with facile microwave treatment paves the way to sustainable, high yield and cost-effective synthesis of GQDs for practical applications.

scholarly journals Transforming Carbon Black into Graphene Oxide Quantum Dots by Pulsed Laser Ablation in Ethanol

2020 ◽  
Vol 58 (11) ◽  
pp. 808-814
Author(s):  
Jung-Il Lee ◽  
Jeong Ho Ryu
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Laser Ablation ◽  
Carbon Black ◽  
Graphene Quantum Dots ◽  
Pulsed Laser ◽  
Blue Emission ◽  
Pulsed Laser Ablation ◽  
Absorption Bands ◽  
Graphene Oxide Quantum Dots

Graphene oxide quantum dots (GOQDs) are nanometer-sized graphene oxide fragments that exhibit unique properties, making them interesting candidates for a range of new applications. Carbon black, one of the commercially available carbon precursors, is produced by the thermal decomposition or incomplete combustion of organic compounds. It is commonly used as a supporting material for catalysts because of its excellent electrical conductivity, high surface area, and stability. In this paper, we report the transformation of carbon black into GOQDs in 10 min using a one-step facile approach. This transformation was achieved by pulsed laser ablation (PLA) in ethanol using the earth-abundant and low-cost carbon black as precursor. Only ethanol and carbon black were used for the transformation. The carbon clusters ablated from the carbon black were completely transformed into GOQDs with a homogeneous size distribution and heights in the range of 0.3-1.7 nm. This confirmed that the transformed GOQDs consisted of only single- or few-layered graphene quantum dots. The UV-vis spectra showed absorption bands at 215, 260, and 320 nm, which were attributed to the π→π* transition of the C=C of the sp<sup>2</sup> C bond in the sp<sup>3</sup> C matrix. A distinct blue emission peak at 450 nm was evident at an excitation wavelength of 360 nm. The broader PL emission spectra are due to the oxygen-related functional groups emitting PL between 300 and 440 nm.

Graphene quantum dots as a novel sensing material for low-cost resistive and fast-response humidity sensors

2015 ◽  
Vol 218 ◽  
pp. 73-77 ◽  
Author(s):  
Virginia Ruiz ◽  
Iván Fernández ◽  
Pedro Carrasco ◽  
Germán Cabañero ◽  
Hans J. Grande ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
Fast Response ◽  
Humidity Sensors ◽  
Sensing Material

scholarly journals Laser wavelength modulated pulsed laser ablation for selective and efficient production of graphene quantum dots

RSC Advances ◽  
2019 ◽  
Vol 9 (24) ◽  
pp. 13658-13663 ◽  
Author(s):  
Sukhyun Kang ◽  
Jeong Ho Ryu ◽  
Byoungsoo Lee ◽  
Kyung Hwan Jung ◽  
Kwang Bo Shim ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Laser Ablation ◽  
Biomedical Applications ◽  
Graphene Quantum Dots ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Laser Wavelength ◽  
Efficient Production ◽  
Laser Ablation In Liquid ◽  
Graphene Oxide Quantum Dots

Graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs) can be selectively produced by wavelength-modulated pulsed laser ablation in liquid (PLAL) method, which can used in different applications such as optoelectronic and biomedical applications, respectively.

Graphene quantum dots from fishbone carbon nanofibers

RSC Advances ◽  
2016 ◽  
Vol 6 (54) ◽  
pp. 48504-48514 ◽  
Author(s):  
D. Torres ◽  
J. L. Pinilla ◽  
E. M. Gálvez ◽  
I. Suelves
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Carbon Nanofibers ◽  
Graphene Quantum Dots ◽  
Differential Centrifugation ◽  
Graphene Oxide Quantum Dots

Photoluminescent graphene oxide quantum dots (GOQD) obtained from chemically oxidized fishbone carbon nanofibers (CNF) and separated by degressive differential centrifugation.

Facile Synthetic Method for Pristine Graphene Quantum Dots and Graphene Oxide Quantum Dots: Origin of Blue and Green Luminescence

2013 ◽  
Vol 25 (27) ◽  
pp. 3657-3662 ◽  
Author(s):  
Fei Liu ◽  
Min-Ho Jang ◽  
Hyun Dong Ha ◽  
Je-Hyung Kim ◽  
Yong-Hoon Cho ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Graphene Quantum Dots ◽  
Pristine Graphene ◽  
Synthetic Method ◽  
Green Luminescence ◽  
Graphene Oxide Quantum Dots

N-Doped Graphene Quantum Dots Using Different Bases

2019 ◽  
Vol 18 (01) ◽  
pp. 1850017
Author(s):  
M. Jaya Prakash Naik ◽  
Sourajit Mohanta ◽  
Peetam Mandal ◽  
Mitali Saha
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Optical Properties ◽  
Graphene Quantum Dots ◽  
Ammonium Hydroxide ◽  
Particle Size Analyzer ◽  
Vis Spectroscopy ◽  
Doped Graphene ◽  
Formation Conditions

Photoluminescent graphene quantum dots (GQDs) have received tremendous attention due to their sui generis chemical, electronic and optical properties but fabricating the pristine quality of GQD is extremely challenging. Herein, we have reported the pyrolysis of citric acid which in the presence of different bases viz. triethylamine, ammonium hydroxide and urea, produced N-doped GQDs at different pH. The effect of different pH has been studied in detail to optimize the formation conditions of the GQD. Ultraviolet–visible (UV–Vis) spectroscopy and normalized fluorescence spectra were applied to analyze the optical properties of the GQD. The mean particle size was analyzed by a particle size analyzer (dynamic light dispersion).

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