Optical fullerene composites

Scharber M. C., Schultz N. A., Sariciftci N. S. and Brabec C. J. (2003), Optical- and photocurrent-detected magnetic resonance studies on conjugated polymer/ fullerene composites , Phys. Rev. B 67, 085202-1-085202-7. 

Montanari 1, Nogueira AF, Nelson J, Durrant JR, Winder C, Loi MA, Sariciftci NS, Brabec CJ (2001) Transient optical studies of charge recombination dynamics in a polymer/fullerene composite at room temperature. Appl Phys Lett 81 3001... 

Although there have been great advances in covalent functionalization of fullerenes to obtain surface-modified fullerene derivatives or fullerene polymers, the application of these compounds in composites still remains unexplored, basically because of the low availability of these compounds [132]. However, until now, modified fullerene derivatives have been used to prepare composites with different polymers, including acrylic [133,134] or vinyl polymers [135], polystyrene [136], polyethylene [137], and polyimide [138,139], amongst others. These composite materials have found applications especially in the field of optoelectronics [140] in which the most important applications of the fullerene-polymer composites have been in the field of photovoltaic and optical-limiting materials [141]. The methods to covalently functionalize fullerenes and their application for composites or hybrid materials are very well established and they have set the foundations that later were applied to the covalent functionalization of other carbon nanostructures including CNTs and graphene. 

Two different kinds of composite samples were examined. We call one of them polymeric because optical absorption spectra revealed considerable broadening and blue shift typical for polymerized C6o- Another sign of polymerization is a red shift of 8 cm 1 and broadening of C6o pentagonal pinch mode Ag(2) in Raman spectra. X-ray diffraction patterns of these samples did not show crystalline metal and revealed only some features of amorphous and crystalline C6o- Another kind was obtained for layer-by-layer deposition by alternate opening Sn and C6o shutters the fullerene deposition flux being 10 times less intense. Optical absorption spectra of these samples revealed absence of the main C6o bands. SEM... 

Fig. 1.18. Spectrally resolved pump-probe spectrum of pristine MDMO-PPV compared to highly fullerene-loaded MDMO-PPV/PCBM composites at various delay times, (a) Absorption spectrum of a pure MDMO-PPV film (solid line) and AT/T spectrum at 200 fs pump-probe delay (dashed line), (b) AT/T spectra of the MDMO-PPV/PCBM blend (1 3 wt. ratio) at various time delays following resonant photoexcitation by a sub-10-fs optical pulse. The CW PA of the blend ( ) was measured at 80 K and 10-5 mbar. Excitation was provided by the 488 nm line of an argon ion laser, chopped at 273 Hz...

The ability to synthesize carbon nanostmctures, such as fullerenes, carbon nanotubes, nanodiamond, and mesoporous carbon functionalize their surface or assemble them into three-dimensional networks has opened new avenues for material design. Carbon nanostructures possess tunable optical, electrical, or mechanical properties, making them ideal candidates for numerous applications ranging from composite structures and chemical sensors to electronic devices and medical implants. 

We have developed such a multiphase composite using sol-gel processing which produces large size bulks of excellent optical quality (d). In this approach, we prepare highly porous monolith gel (in the present case silica) and thermally process it. The pores in the silica monolith under our processing conditions are in the nanoscale region ( 5 nm). This allows various molecules (such as fullerene) to be adsorbed in the pores by diffusion of a solution followed by evaporation of the solvent. Then the pores are filled with a polymerizable liquid such as methyl methacrylate (MMA) which is then... 

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