Electronics and Optics of Graphene Nanoflakes: Edge Functionalization and Structural Distortions

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• 作者：Caterina Cocchi ; Deborah Prezzi ; Alice Ruini ; Marilia J. Caldas ; Elisa Molinari
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：August 23, 2012
• 年：2012
• 卷：116
• 期：33
• 页码：17328-17335
• 全文大小：508K
• 年卷期：v.116,no.33(August 23, 2012)
• ISSN：1932-7455

文摘

The effects of edge covalent functionalization on the structural, electronic, and optical properties of elongated armchair graphene nanoflakes (AGNFs) are analyzed in detail for a wide range of terminations, within the framework of Hartree鈥揊ock-based semiempirical methods. The chemical features of the functional groups, their distribution, and the resulting system symmetry are identified as the key factors that determine the modification of strutural and optoelectronic features. While the electronic gap is always reduced in the presence of substituents, functionalization-induced distortions contribute to the observed lowering by about 35鈥?5%. This effect is paired with a red shift of the first optical peak, corresponding to about 75% of the total optical gap reduction. Further, the functionalization pattern and the specific features of the edge鈥搒ubstituent bond are found to influence the strength and the character of the low-energy excitations. All of these effects are discussed for flakes of different widths, representing the three families of AGNFs.