Estudo da luminescência e eficiência quântica de materiais híbridos de sílica/orgânico dopados com Rodamina 6G

• Autor(a) principal: Rodrigues, Lucas Moretto [UNESP]
• Data de Publicação: 2017
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/156967; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2018-08-30/000906245.pdf
• topic: Física aplicada; Processo sol-gel; Silica; Luminescencia; Absorção da luz; Polímeros; Alcóxidos; Silicio; Espectroscopia de fluorescencia; Etanol

The sol-gel process allows to produce organic-inorganic hybrid materials (OIHM), which can be obtained in various shapes such as particles, fibers, glass gels and thin films, with several applications. Among these materials, hybrid Silica/organic materials (ORMOSIL) are currently studied due to the combination of Silica and organic polymers properties. In addition, the hybrid matrix can be doped with organic molecules, allowing preparation of advanced photoactive materials. Among these molecules, stands out Rhodamine 6G (R6G), a laser dye with high fluorescence emission and high quantum efficiency. In this work, we prepared hybrid Silica/organic materials derived from Silicon alkoxides 3-glycidoxypropyltrimethoxysilane (GPTS) and tetraethylorthosilicate (TEOS) by sol-gel process. The liquid hybrid matrix was doped with R6G in concentrations between 0.001 mmol/L and 2.5 mmol/L. From the doped hybrid matrix, xerogels were prepared by oven drying. Absorbance, fluorescence and fluorescence quantum yield were studied for doped hybrid matrix in liquid (sol) and solid phases (xerogel), as well as doped ethanol. The maximum absorbance of samples occurs around 530 nm. Fluorescence spectra were also determined, revealing concentration and host medium dependence. The fluorescence spectra shift to lower energies as the dye concentration increases. Solutions with 0.05 mmol/L of R6G in ethanol and in liquid hybrid matrix showed the highest fluorescence for these host mediums. For the xerogels, the highest fluorescence occurred at 4.41 mmol/L of R6G. The quantum yield was maximized for the liquid hybrid matrix with 0.001 mmol/L, as well as in the ethanol solutions. The quantum yield decays as the dye concentration increases, occurring quenching and molecular aggregation