• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1015-1019
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• 1995

The electronic structures and properties of the neutral and multiply charged C60n ions (n=2+ to 6-) with spin states have been investigated by semi-empirical MNDO calculations. In the ground state, C601- has the lowest total energy and the highest binding energy. The neutral C60 ion is supposed to have a high ionization potential and a high electron affinity. The HOMO and LUMO positions are lower in the cationic C60 than in the anionic C60. The LUMO energy becomes increasingly positive from C601- to C606- and the HOMO energy becomes increasingly negative from C602+ to C60. The HOMO-LUMO gap of the neutral C60 ion is higher than that of the multiply charged C60 ions. From the HOMO-LUMO gap, it seems reasonable to expect that electrons of the multiply charged C60 ions will be more polarizable than those of the neutral C60 ion. The HOMO and LUMO energies increase as the negative charge increases.

• Composites Research
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• v.26 no.2
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• pp.111-115
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• 2013

Aluminum-based composites containing $C_{60}$-fullerenes are produced by hot rolling of ball-milled powder. The grain size of aluminum is effectively reduced to ~100 nm during ball-milling processes, leading to grain refinement strengthening of the composite. Furthermore, $C_{60}$-fullerenes are gradually dispersed during ball-milling processes and hence the strength of the composite increases with the volume of $C_{60}$-fullerenes. The composite containing 10 vol% $C_{60}$-fullerenes with a grain size of ~ 100 nm exhibits ~1 GPa of compressive strength.

• Polymer(Korea)
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• v.33 no.5
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• pp.407-412
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• 2009

Vacuum deposited N,N-di-1-naphthyl-N,N-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD) as a hole transporting (HTL) materials in OLEDs was placed on PEDOT-PSS, a hole injection layer (HIL). PEDOT-PSS was spin-coated on to the ITO glass. $C_{60}$-doped NPD-$C_{60}$(10 wt%) film was formed via co-evaporation process and the morphology of NPD-$C_{60}$ films was investigated using XRD and AFM. The J - V, L - V and current efficiency of multi -layered devices were characterized. According to XRD results, the deposited $C_{60}$ thin film was partially crystalline, but NPD-$C_{60}$ film was observed not to be crystalline, which indicates that $C_{60}$ molecules are uniformly dispersed in the NPD film. By using $C_{60}$-doped NPD-$C_{60}$ film as a HTL, the current density and luminance of multi-layered ITO/PEDOT-PSS/NPD-$C_{60}/Alq_3$/LiF/Al device were significantly increased by about 80% and its efficiency was improved by about 25% in this study.

• Carbon letters
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• v.11 no.1
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• pp.9-12
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• 2010

The synthesis of $C_{60}$@MWCNT was carried out at room temperature (${\sim}25^{\circ}C$) from arc-discharge prepared Multi-wall carbon nanotubes (MWCNTs). They were oxidized and acid treated for tube opening. Then $C_{60}$ molecules were encapsulated into MWCNTs by wetting them with $C_{60}$-toluene solution for several minutes followed by ultrasonification. $C_{60}$@MWCNT was cleaned by pure toluene to remove any excess $C_{60}$. $C_{60}$@MWCNT was characterized by electron microscopy, which showed large scale filling of $C_{60}$ into MWCNTs. It was observed that the mechanism of insertion of $C_{60}$ into MWCNTs may be due to the capillary suction at the opening ends of MWCNTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.571-571
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• 2012

We discovered the formation of C60 aggregates in solution by means of photoluminescence spectroscopic study on C60 in solutions. From the in-depth investigation of temperature dependence of the luminescence of C60 in toluene, benzene and CS2 solutions, we reported that the C60 aggregates are formed during cooling at the freezing temperature of these solvents. Furthermore, the C60 aggregates can be changed to stable structures by irradiating with UV pulse-laser (Nd:YAG laser, 355nm). As a consequence, we could obtain nano-scale photo-polymerized C60 clusters, which appear as round-shaped nano- scale particles in high resolution transmission electron-microscopy (HRTEM) images. However, the yield of the nano-scale C60 clusters obtained by this method is too small. So we designed and developed a system to obtain C60 cluster of macroscopic quantity by using ultrasonic nebulizer. In this system, C60 solution was vaporized to several micro-sized droplets in vacuum, resulting in the formation of C60 aggregates by evaporating solvent (toluene). The system was invented to produce nano-scale carbon clusters by the irradiation of UV light upon C60 aggregates in vacuum. We have characterized the products, C60 cluster, obtained from the system by using UV absorption spectra and HPLC spectra. Although the products have a possibility of inclusion various forms of C60 cluster, results support that the product formed from the system by using vaporizer method establishes a new method to obtain C60 cluster in macroscopic quantity. In the presentation, the details of the system and the results of characterization are reported.

• Polymer(Korea)
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• v.32 no.4
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• pp.372-376
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• 2008

Vacuum deposited 4,4',4"-tris(N-(2-naphthyl)-N-phenylamino)-triphenylamine (2-TNATA), used as a hole injection (HIL) material in OLEDs, is placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in the devices. C60-doped 2-TNATA:C60 (20 wt%) film was formed via co-evaporation process and molecular ordering and topology of 2-TNATA:C60 films were investigated using XRD and AFM. The J-V, L-V and current efficiency of multi-layered devices were characterized as well. Vacuum-deposited C60 film was molecularly oriented, but neither was 2-TNATA:C60 film due to the uniform dispersion of C60 molecules in the film. By using C60-doped 2-TNATA:C60 film as a HIL, the current density and luminance of a multi-layered ITO/2-TNATA:C60/NPD/$Alq_3$/LiF/Al device were significantly increased and the current efficiency of the device was increased from 4.7 to 6.7 cd/A in the present study.

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.452-457
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• 1996

The effects caused by the ionization on the electronic structure and geometry on C60 are studied by the modified Su-Schriffer-Heeger (SSH) model Hamiltonian. After the ionization of C60, the bond structure of the singly charged C60 cation is deformed from Ih symmetry of the neutral C60 to D5d, C1, and C2, which is dependent upon the change of the electron-phonon coupling strength. The electronic structure of the C60+ cation ground state undergoes Jahn-Teller distortion in the weak electron-phonon coupling region, while self-localized states occur in the intermediate electron-phonon region, but delocalized electronic states appear again in the strong electron-phonon region. In the realistic strength of the electron-phonon coupling in C60, the bond structure of C60+ shows the layer structure of the bond distortion and a polaron-like state is formed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.598-601
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• 2000

We investigated the fabrication of Si nanoparticle and $C_{60}$ thin films by pulsed laser ablation. As a result, we observed visible green photoluminescence spectra in the Si/C$_{60}$ multilayer films after laser annealing. It is considered that this green photoluminescence is occurred from SiC particles, which is produced reaction of Si nanoparticles with $C_{60}$ via laser annealing.ing.

• Elastomers and Composites
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• v.50 no.2
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• pp.126-131
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• 2015

$C_{60}$ nanowhiskers were synthesized from $C_{60}$ by liquid-liquid interfacial precipitation (LLIP) using $C_{60}$-saturated toluene and isopropyl alcohol. The $WO_3$ nanoparticles were synthesized by adding $3.8{\times}10^{-4}$ mole amount of ammonium metatungstate hydrate ($H_{26}N_6O_{40}W_{12}{\cdot}H_2O$) to 500 ml of distilled water, and the resulting solution was heated on a hot plate for 4 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were prepared with $C_{60}$ nanowhiskers and $WO_3$ nanoparticles in an electric furnace at $700^{\circ}C$ in an argon gas atmosphere for 2 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. UV-vis spectroscopy was used to evaluate the performance of the $C_{60}$ nanowhiskers/$WO_3$ nanocomposites as a photocatalyst in the degradation of organic dyes, such as methylene blue (MB) and brilliant green (BG) under ultraviolet light (254 nm).

• Elastomers and Composites
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• v.38 no.2
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• pp.147-156
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• 2003

Synthesis of fullerene oxides by fullerenes [$C_{60},\;C_{70}$] and several oxidants such as benzoylperoxide, trichloroisocyanuric acid, methyltrioxorhenium(VII), iodosobenzene, phosphorous pentoxide take place under ultrasonic condition at room temperature. The MALDI-TOF MS,UV-visible spectra and HPLC analysis confirmed that the products of fullerenes oxidation are [$C_{60}(O)_n$], ($n=1{\sim}3$ or n=1) and [$C_{70}(O)_n$], ($n=1{\sim}2$ or n=1). As compared with the reactivity of epoxidation of fullerenes [$C_{60},\;C_{70}$], the reaction rate of $C_{70}$ was lower than that of $C_{60}$ under same reaction condition.