Role of Edge Geometry and Magnetic Interaction in Opening Bandgap of Low‐Dimensional Graphene

Zhu, Yong; Lian, Jianshe; Jiang, Q.

doi:10.1002/cphc.201301127

Cited by 6 publications

(1 citation statement)

References 75 publications

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“…However, that is different from a quantum dot, whose PL emission peak is independent of the excitation wavelength, but the intensity of the PL emission is dependent on the excitation wavelength, when its size, morphology, and surface functional groups are defined. Several mechanisms were proposed to illustrate the origin of the excitation wavelength dependence of the PL property of GQDs. − The generally accepted explanation is that quantum size, zigzag edge sites, recombination of localized electron–hole pairs, and defect effects were involved in the PL emission. ,,− The first three of them were regarded as intrinsic state emission and the last one defined as the defect state emission. However, the dominant factor remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Effect of Lateral Size of Graphene Quantum Dots on Their Properties and Application

Zhang

Liu

Wang

et al. 2016

ACS Appl. Mater. Interfaces

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Well-defined graphene quantum dots (GQDs) are crucial for their biological applications and the construction of nanoscaled optoelectronic and electronic devices. However, as-synthesized GQDs reported in many works assume a very wide lateral size distribution; thus, their apparent properties cannot truthfully reflect intrinsic properties of the well-defined GQDs, and more importantly, the applications of GQDs will be affected and limited as well. In this work, we demonstrated that different sized GQDs with a narrow size distribution could be obtained via gel electrophoresis of the crude GQDs prepared through a photo-Fenton reaction of graphene oxide (GO). It is illustrated that the photoluminesce (PL) emissions of the well-defined GQDs originated mainly from the peripheral carboxylic groups and conjugated carbon backbone planes through fluorescence and UV-vis spectroscopies. More importantly, our findings challenge the notion that the excitation wavelength dependent PL property of the as-synthesized GQDs is the intrinsic property of the size-defined GQDs. Preliminary data at the cellular level indicated that the small sized GQDs exhibit weaker quenching DNA dye ability but higher toxicity to the cells compared to that of the as-synthesized GQDs. This discovery is essential to explore applications of the GQDs in pharmaceutics and to understand the origin of the optoelectronic properties of GQDs.

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Section: Introductionmentioning

confidence: 99%

Effect of Lateral Size of Graphene Quantum Dots on Their Properties and Application

Zhang

Liu

Wang

et al. 2016

ACS Appl. Mater. Interfaces

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Recent Advances in Graphene Homogeneous p–n Junction for Optoelectronics

Tian

Tang

Teng

et al. 2019

Adv Materials Technologies

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Graphene has been widely used as electrodes and active layers in optoelectronics due to its diverse excellent performances, such as high mobility, large thermal conductivity and high specific surface area etc. Methodology for constructing p-n junction has becoming an important consideration in improving the performance of optoelectronic devices and broadening of its application in related fields. Currently, graphene based p-n junction has been explored and different structures have also been investigated. This review paper summaries the recent progress on graphene homogeneous p-n junction, ranging from preparation of front-end materials (e.g. p-and n-type graphene) to building of planar and vertical p-n junctions. Furthermore, p-n junction via electrical modulation is described. The requirements for building the graphene homogeneous p-n junction, and the advantages and drawbacks of the different structures of the p-n junction are also discussed. Finally, a preferential technique to fabricate high performance p-and n-type graphene and building of the p-n junction is evaluated. This paper therefore provides an important indication on the future direction on the application of graphene in optoelectronics. 2 ranging applications, such as logical rectifier circuit [10,11] , field-effect optoelectronic transistor [12-14] , multimode non-volatile memory [15] , rectifier memory [16,17] , optoelectronic storage [18,19] , photovoltaic device [20] , photodetector [21,22] and gas sensor [23,24] etc. Consequently, it is obvious to study new material system for the p-n junction that will enhance the performance of current devices and also lead to the development of new devices. In general, p-n junction can be categorized into heterojunction and homojunction. If same materials are used, the p-n junction is known as homogeneous junction or homojunction. There are many advantages of homogeneous p-n junction, for example, there is no issue on lattice mismatch, which will result in surface defects, since p and n layers are of the same materials. Moreover, the use of the same materials in homogeneous p-n junction leads to uniform energy band gap across the device structure, as shown in Figure 1a. Depletion region is formed at the junction between p and n regions, and the alignment of Fermi level (E f) promotes band bending at the depletion region when the same semiconducting materials are used to construct the p-n junction, as represented in Figure 1b. Such homogeneous p-n junction is of great significance in the field of optoelectronics. Figure 1c illustrates the charge transport mechanism under illumination. Upon radiation of light with certain wavelength (hυ ≧ Eg), electrons jump to conduction band in p, n and depletion regions. These electrons and holes arriving at the depletion region are subsequently swept into n-type and p-type regions respectively via the built-in field. As a result, current is generated and a certain voltage is produced due to the accumulation of charges under open circuit conditions. Furthermore, this lead...

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Cohesive‐Energy‐Resolved Bandgap of Nanoscale Graphene Derivatives

et al. 2014

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With a size-dependent cohesive energy formula for two-dimensional coordinated materials, the bandgap variation in quantum dots and nanoribbons of graphene derivatives, such as graphane, fluorographene and graphene oxides, is investigated. The bandgap is found to increase substantially as the diameter or width of the nano-sized material decreases. The bandgap variation is attributed to the change in cohesive energy of edge carbon atoms, and is associated with the physicochemical nature and degree of edge saturation. These predictions agree with previously reported computer simulation results, and have potential application in wide-band optics and optoelectronics.

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Role of Edge Geometry and Magnetic Interaction in Opening Bandgap of Low‐Dimensional Graphene

Cited by 6 publications

References 75 publications

Effect of Lateral Size of Graphene Quantum Dots on Their Properties and Application

Effect of Lateral Size of Graphene Quantum Dots on Their Properties and Application

Recent Advances in Graphene Homogeneous p–n Junction for Optoelectronics

Cohesive‐Energy‐Resolved Bandgap of Nanoscale Graphene Derivatives

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