Graphene Oxide Covalently Functionalized With Organic Molecules For Broadband Optical Limiting Performance

Optical limiting is a nonlinear optical (NLO) phenomenon that when a bunch of light passes through the optical limiting materials, the materials can reduce its intensity to the human eyes and sensor can be acceptable level. Graphene is a new two-dimensional material comprising layers of carbon atoms arranged in six-membered rings, which has been a subject of extensive academic and commercial interest for potential use as the active materials in the fields of optical limiting properties. However, because of its poor solubility in common solvents, there are only few materials chemically derived from graphene can be used for optical limiting. In this thesis, we designed and synthesized a series of new graphene derivates covalently functionalized with organic molecules, most of which possess outstanding optical limiting properties.In the first chapter, we highlight the important aspects of graphenes, including preparation methods, chemical modification and potential applications for optical limiting in detail.In the second chapter, a Graphene Oxide (GO) covalently functionalized with zinc phthalocyanine (PcZn), GO-PcZn, was synthesized by amidation reaction. The formation of the amido bond between PcZn and GO was confirmed by x-ray photoelectron and Fourier transform infrared spectroscopy. At the same level of linear extinction coefficient, GO-PcZn exhibited much larger nonlinear optical extinction coefficients and broadband optical limiting performance than GO at both 532 and 1064 nm.In the third chapter, A soluble GO axially substituted gallium phthalocyanine (PcGa) hybrid material (GO-PcGa) was for the first time synthesized by the reaction of tBu4PcGaCl with GO in anhydrous DMSO at 110℃in the presence of K2CO3. The formation of a Ga-O bond between PcGa and GO was confirmed by x-ray photoelectron spectroscopy. At the same level of concentration of 0.1 g/L, GO-PcGa exhibit much larger NLO extinction coefficients and strong OL performance than GO, tBu4PcGaCl and C6o at both 532 and 1064 nm.In the forth chapter, GO was modified covalently with N-(4-anilinobenzoyl) carbazole using acylamidation reaction. The hybrid material exhibited lager nonlinear extinction coefficient and much better optical limiting property in comparison with GO both at 532 nm and 1064 nm. This could be due to the donor-acceptor system and the extendedπ-πconjugate of GO attributed to the introduction of N-(4-anilinobenzoyl) carbazole. In order to study the mechanism of nonlinear optical, especially optical limiting in GO, GO-based hybrid material was synthesized by covalently bonding GO and polyhedral oligomeric silsesquioxane together. The amido bond was shown clearly in FTIR spectra of samples. The hybrid material exhibited improved solubility in CHCl3 and enhanced fluorescence intensity in comparison with GO.