Search query: blue luminescent graphene semiconductor

Related papers:

abstract: Abstract A facile chemical oxidation and exfoliation method has been developed to prepare luminescent graphene quantum dots (GQDs) using commercial carbon fibers as the raw material, which were synthesized from pitch through an annealing process at 1500 degC. The as prepared GQDs, in the thickness range of 1 2 graphene layers, exhibit an excitation independent photoluminescence (PL) behavior similar to that of semiconductor quantum dots, and can be dissolved in water and common polar solvents. This approach has enabled a simple and effective way for production of the GQDs solution, which could be separated into blue and green photoluminescence (PL) GQDs with different dialysis bags.
author_names: Minmin Xie

Yanjie Su

Xiaonan Lu

Yaozhong Zhang

Zhi Yang

Yafei Zhang
title: Blue and green photoluminescence graphene quantum dots synthesized from carbon fibers
year: 2013

abstract: The need for highly efficient devices with longer operating lives in the blue wavelength region is increasing. Herein, we showed that hexagonal boron nitride, as a blue luminescent material, is promising because it is a wide bandgap semiconductor with very high thermal and chemical stabilities and can be used in devices operating under extreme conditions. Specifically, through the highly luminous properties of exfoliated hexagonal boron nitride (Exf hBN) a blue emission device equipped with a field emission array using carbon nanotube as an excitation source was fabricated and its stable operation has been demonstrated. Furthermore, the cathodoluminescent device is thinner than conventional lamps when using the ultra thin Exf hBN film and graphene as an electrode. The blue fluorescence of Exf hBN may allow new devices to be developed with extraordinary properties for applications from optoelectronics to biotechnological devices.
author_names: Dongju Lee

Sung Ho Song
title: Ultra thin ultraviolet cathodoluminescent device based on exfoliated hexagonal boron nitride
year: 2017

abstract: Graphene Quantum Dots (GQDs) are considered to be a new class of materials with distinctive photoluminescence and low toxic level properties. Herein, we have reported the preparation of GQDs at different pH (pH 5, 8, 10, and 14) from pyrocatechol. UV Visible absorption and normalized fluorescence spectra were applied to analyze the optical properties of GQDs at different pH. DLS and AFM had been performed to study the mean particle size and the morphology of the GQDs. Further, the photocatalytic behavior of the synthesized GQDs obtained at pH 10 was used in the degradation of dyes viz. Methylene Blue and Methyl Orange under visible light irradiation. The influence of certain parameters such as pH of the GQD, contact time, a dosage of GQDs, and the kinetic model was demonstrated. The plausible mechanism of degradation of the toxic dyes based on GQDs under visible light illumination was discussed, too.
author_names: Peetam Mandal

Kandarpa Kumar Nath

Mitali Saha
title: Efficient Blue Luminescent Graphene Quantum Dots and their Photocatalytic Ability Under Visible Light
year: 2020

abstract: Graphene quantum dots (GQDs) which are elongated strips of few layer of graphene with straight edges attract a lot of attention for their wide potential applications, mainly because of their photoluminescence properties [1] In addition, GQDs could inherit from both the rich nonlinear (NL) optical properties of graphene as well as the control and the versatility offered by the quantum dots. However, NL characterizations of such structures remain scarce. Here we characterize experimentally in the picosecond regime the NL refractive index and the NL absorption of blue luminescent GQDs in solution, in the ultraviolet, visible and infrared domains [2]
author_names: Charles Ciret

Hongzhen Wang

Christophe Cassagne

Georges Boudebs
title: Nonlinear Characterization of Blue Luminescent Graphene Quantum Dots in Water in Ultraviolet, Visible and Infrared Domains
venue: 2019 Conference on Lasers and Electro Optics Europe European Quantum Electronics Conference (CLEO/Europe EQEC)
year: 2019

abstract: Erythrosine B (ErB) is a xanthenes approved dye that widely used in various fields such as foods, drugs and cosmetics. This work intended to analyze the interaction of this dye on synthesized graphene quantum dot conjugated cysteamine functionalized gold nanoparticles. Pyrolysis of citric acid was applied to graphene quantum dots (GQDs) synthesis. These are zero dimensional materials promising considerable applications because of their extraordinary physicochemical properties. In this work, to improve its applications conjugates of GQDs and gold nanoparticles (GQD AuNPs) are synthesized and characterized with FESEM, TEM, EDX and FTIR techniques. Interaction of ErB with synthesized conjugates was investigated using fluorescence technique and the results demonstrate that ErB can quench fluorescence of GQD AuNPs conjugates, considerably. At last, we used of this good interaction for construction sensor for detection of ErB in the concentration range of 1.2 nM to 50 nM and the obtained LOD was 0.03 nM (S/N 3) with correlation coefficient of (99%
author_names: Maryam Farmani

Hossein Peyman

Hamideh Roshanfekr
title: Blue luminescent graphene quantum dot conjugated cysteamine functionalized gold nanoparticles (GQD AuNPs) for sensing hazardous dye Erythrosine B.
venue: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
year: 2019

abstract: Abstract L cysteine, a natural amino acid, was used to prepare Graphene quantum dots (GQDs) by the bottom up approach in a one step direct carbonization. The morphology and the fluorescent behaviour of the prepared GQDs were analyzed. Selective fluorescence based sensing of curcumin was demonstrated using the prepared GQDs. The sensing was found to be independent of the pH of GQDs and the curcumin was detected even in its degraded form in the alkaline media. Secondary inner filter effects explicate the sensing of curcumin by the GQDs. A static cum dynamic quenching in the fluorescent intensity of GQDs was observed upon addition of curcumin. Curcumin sensing was found to be selective among a number of biomolecules and metal ions.
author_names: C Sudarsanakumar

Subin Thomas

Smitha C Mathew

S Arundhathi

D Rithesh Raj

S Prasanth

Riju K Thomas
title: Selective sensing of curcumin using L cysteine derived blue luminescent graphene quantum dots
venue: Materials Research Bulletin
year: 2019

abstract: Abstract The present investigation deals with a comparative assessment of various techniques for the synthesis of blue luminescence Graphene Quantum Dots (GQDs) using various equipments like furnace, domestic microwave synthesiser and scientific microwave synthesiser using citric acid as a precursor. A bottom up method was adapted to develop photoluminescent (PL) GQDs and assessed for luminescence intensity of GQDs at different environmental conditions. The methodology requires very less concentration of NaOH to disperse GQDs. The present approach is advantageous over other conventional organic solvent mediated synthesis, as it requires less time, easy to reproduce and disperse in water, furthermore it produces stable fluorescence for a longer period of time at ambient temperature conditions. The synthesized GQDs are primarily characterized by UV for detection of the fluorescence intensity and simultaneously Ultraviolet Visible (UV Vis) spectroscopy and Fourier Transform Infra Red (FTIR) Spectroscopy to assess the up conversion from the precursor molecule. Apart from these techniques, Particle Size and Zeta Potential, Scanning Electron Microscopy (SEM) Elemental Analysis (EDX) Raman Spectroscopy and Fluorescence spectrophotometry were used to characterise synthesized GQDs.
author_names: Mahesh P More

Pravinkumar H Lohar

Ashwini G Patil

Pravin Onkar Patil

Prashant K Deshmukh
title: Controlled Synthesis of Blue Luminescent Graphene Quantum Dots From Carbonized Citric Acid: Assessment of Methodology, Stability, and Fluorescence in an Aqueous Environment
year: 2018

abstract: Graphene oxide quantum dots (GOQDs) with different oxygenation levels were successfully prepared using a facile, rapid, and cost effective microwave assisted hydrothermal method under neutral conditions using hydrogen peroxide (MGOH) or potassium permanganate (MGOK) as an oxidizing agent. GOQDs with an average diameter of 7 12 nm for both MGOH and MGOK samples were observed using transmission electron microscopy (TEM) X ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that MGOH exhibited a high quantity of C O and CO groups in its structure, whereas MGOK consisted of highly ordered sp2/sp3 bonds in its aromatic unit and had less oxygenated functional groups. The photoluminescence measurements showed that MGOH and MGOK QDs emitted yellowish green and blue light with quantum yields of 15.1% and 8.4% respectively. The luminescence mechanisms of MOGK and MGOH were attributed to p p* and n p* electron transitions in C C/CC bonds and in p* states to non bonding oxygen states, respectively. Density functional theory calculations were employed to determine the optical absorption of GOQDs in terms of surface functional groups and oxygenation degrees. Theoretical calculations demonstrate that the high oxygenation degree of GOQDs resulted in band gap reduction and light absorption due to electron transitions. Our theoretical and experimental results suggested that GOQDs with high quantum yields can serve as promising materials in applications including biosensing, imaging, and labeling.
author_names: Chechia Hu

Tzer-Rurng Su

Tzu-Jen Lin

Chien-wei Chang

Kuo-Lun Tung
title: Yellowish and blue luminescent graphene oxide quantum dots prepared via a microwave assisted hydrothermal route using H2O2 and KMnO4 as oxidizing agents
year: 2018

abstract: Abstract Traditionally, graphene quantum dots are prepared by fragmentation of graphene sheets into the nanoscale particles of controlled sizes followed by band gap adjustment by doping with electron donating elements. Our novel synthetic aqueous arc discharge process has been developed to produce the blue luminescent graphene quantum dots (bGQDs) The resulting bGQDs are ~15 nm in diameter and the amount of oxygen including functional groups can be controlled to 27.4% and 30.8% at 1 and 4 A of a current level, respectively. The presence of a band gap is confirmed by using scanning tunneling microscopy/spectroscopy (STM/STS) Additionally, we investigated the effect of oxygen doping levels on the band gap by photoluminescence (PL) behaviors and a density functional theory (DFT) The PL emission is red shifted from 397 to 425 nm corresponding to the amount of oxygen including functional groups in bGQDs and the DFT calculation confirms the decrease in a band gap from ~2.0 to ~1.7 eV due to electron donation from oxygen. In addition, our quantum dots have promising applications for practical use in optoelectronics devices. For example, tris dibenzoylmethane mono 1,10 phenanthroline europium (III) (Eu III DP) is incorporated with bGQDs for white light emission and is shown to be successfully fabricated into light emitting polymer films.
author_names: Sejung Kim

Joon Kyo Seo

Jun Hong Park

Youngjun Song

Ying Shirley Meng

Michael J Heller
title: White light emission of blue luminescent graphene quantum dots by europium (III) complex incorporation
year: 2017

abstract: Determination of regular features of mechanisms underlying interactions of nanostructured materials is one of the most important problems on the way to create the new generation of efficient photovoltaic devices. In this paper, we study the luminescent and photoelectric properties of hybrid structures that are formed on the basis of multilayer graphene nanoribbons and semiconductor quantum nanocrystals of the 0D dimension, CdSe/ZnS core/shell quantum dots, and 2D dimension CdSe nanoplates. It is shown that the multiexponential decay of the exciton luminescence of CdSe nanoplates at room temperature is determined by the occurrence of delayed luminescence, which is caused by the presence of trap states on the surface of nanoplates. It is found that, in dry layers of nanoplates on a dielectric substrate and in the composition of hybrid structures with graphene nanoribbons, the efficiency of delayed exciton luminescence of nanoplates increases. It is shown that the rate of increase in the photoconductivity in hybrid structures based on CdSe nanoplates is an order of magnitude higher than the rate of this process in similar structures based on CdSe/ZnS quantum dots, which indicates the formation of an effective energy/charge transfer channel from nanoplates to graphene nanoribbons.
author_names: Ivan A Reznik

Andrey Zlatov

Pavel O Ilin

Roman A Zakoldaev

S A Moshkalev

Anna Orlova
title: Luminescent and Photoelectric Properties of Hybrid Structures Based on Multilayer Graphene and 0D and 2D Semiconductor Quantum Nanocrystals
year: 2020