Um estudo DFT dos efeitos dos substituintes nas propriedades óptica e eletrônicas do grafeno quantum dots

• Autor(a) principal: Santos, Diego Machado dos
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: http://ri.ufs.br/jspui/handle/riufs/11135
• topic: Ciência dos materiais; Densidade funcional; Mecânica quântica; Grafeno; Propriedades ópticas; Propriedades eletrônicas; Teoria do funcional da densidade (DFT); Pontos quânticos de grafeno (GQD); Density functional theory (DFT); Optical properties; Electronic properties; Graphene quantum dots (GQD); ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

Graphene quantum dots (GQD) has been strongly prominent, among the quantum dots. Because their extraordinary and tunable optical, electrical, chemical and structural properties. In opposite to other quantum dots the GQDs can be tuned by edge configuration, shaped and attached chemical functionality and doping with heteroatoms, being able to emit light in all colors of all visible spectrum. The work consists in investigating the optical and electronic properties of the GQDs starting with the simplest structure, the benzene, to larger hexagonal structures like C24H12, and C96H24. The groups R = –COO-, -NHCH3, -NH2, -OR, -OH, -CH3, -F, -CONH2, -COOCH3, -COOH, -CF3, -NO2 and -NH3+in the optical and electronic properties of molecular electronic systems. In the benzene study it was possible to obtain models based on the loads p and s to explain the degeneracy of the HOMO and LUMO orbital and the energy of the gap. With the other systems, it was possible to identify a series associated with the ability to decrease the bandgap of GQDs. This effect was explained by the unfolding of the doubly degenerate HOMO and LUMO orbitals in the substituted GQDs and by the increase and decrease of HOMO and LUMO in the hexassubstituted GQDs.