Preparation of Fullerene (C₆₀) Based SiO₂ Sonogel Hybrid Composites: UV Laser Induced Photo-Polymerization, Morphological, and Optical Properties

Abstract

Fullerene (C60) spheres were successfully embedded by diffusion into a catalyst-free SiO2 sonogel network. By this method, homogeneous and stable solid state hybrid samples suitable for optical characterization were produced. Due to the high porosity exhibited by the sonogel matrix on the nanometric length-scale, the preparation of several C60 doped composites with variable dopant concentrations was achieved. The obtained bulk hybrids were irradiated with a pulsed Kr-F laser system in order to induce photo-polymerization of the implanted C60 guest molecules at optimal experimental conditions established according to the pulsed laser photoacoustic technique (LPAT). The adequate purity level displayed by the sonogel route allowed us to perform optimal optical characterizations of these composites (reference hybrids and photo-polymerized samples) in order to evaluate their photo-physical properties for potential photonic applications. In this work the sonolysis process used to prepare amorphous catalyst-free SiO2:C60 sonogel hybrids and their linear and nonlinear optical (NLO) properties are extensively discussed. UV-VIS absorption-, Photo Luminescent (PL)-, and Raman-spectroscopies in conjunction with nonlinear optical limiting (OL) measurements, gave experimental evidence of the inclusion of C60 molecules within the sonogel environment, the laser induced photo-polymerization process and the induced changes of the optical and NLO-properties. Results are discussed in combination with atomic force microscopy (AFM) studies in order to explore the surface morphology of these samples.

Facile Fabrication of Efficient Organic CMOS Circuits

“…We have recently demonstrated a photoinduced and resist-free patterning technique, which exploits an attractive combination of properties of fullerene materials: (i) they can form oligomeric and polymeric structures during exposure to laser light, − (ii) the exposed and chemically modified material exhibits a distinctly lowered solubility in tuned developer solutions as compared to the pristine material, , and (iii) the laser-exposed (and subsequently solution-developed) material exhibits an essentially intact electron mobility. , Thus, by exposing selected regions of a fullerene film to laser light, and then developing the entire film in a developer solution, a pattern of electronically active fullerene material defined by the incident laser beam is created. The merit of the technique has been demonstrated by the facile patterning of single-component PCBM and C 60 films into well-defined arrays of fully functional n-type FETs. , …”