Industry Academic Cooperation Foundation of Kyunghee University (Gyeonggi-do, KR) scientist Jeung Sun Ahn claims the first use of fullerenes in an organic electroluminescent (EL) display. Although research into fullerene applications has been underway for some time, coaxing a white light photoemission from a fullerene had not been achieved and fullerenes had previously never been used for a display device such as an organic electroluminescent (EL) display.
Ahn developed a fullerene manifold with a characteristic white photoemission in the whole range of visible rays. The fullerene manifold is formed by the covalent bonding between fullerene molecules in a fullerene assembly made by dissolving a substance of fullerene monomers in a single solvent to form a fullerene solution. Then, the fullerene assembly is formed through a solidifying process, followed by optically pumping the fullerene assembly, according to U.S. Patent Application 20100028244.
The optical pumping is accomplished with a YAG laser or Ar ion laser. The time in which the fullerene assembly changes to the fullerene manifold may rely on the strength (power density) of the irradiation of the laser beam and the wavelength of the laser. Five minutes is the time taken when the laser beam has a wavelength of 355 nm, three times the wavelength of a YAG laser, and the fullerene assembly is irradiated at a laser power density of 15.8 mW/mm2.
The fullerene manifold has a size of several or tens of nanometers and a closed shell structure.
The fullerene exists as a solution or a single crystal. Solvents dissolving the fullerene include benzene, toluene, CS2, acetone, tricrene, and chlorobenzene. The fullerene has a degree of freedom of rotation both as a solution and as a single crystal.
In a single crystal at room temperature, a fullerene molecule, i.e., a fullerene monomer, does not have only the freedom of translation, but rotates by a thermal motion. This relates to the fact that the fullerene has an isotropic ball state in which the bonding between fullerene molecules is weak and the anisotropy of the potential of the bonding is small. Accordingly, the bonding between fullerene molecules in a solid body is mainly van der Waals bonding caused by interaction of .pi. electrons.
Thin films of fullerenes, can be patterned by lithography. Since the fullerenes have a sublimation property and can form a thin film, if a latent image can be formed and developed on this thin film, the fullerene can patterned with photolithography to create an organic electroluminescent display.
In a single crystal at room temperature, a fullerene molecule, i.e., a fullerene monomer, does not have only the freedom of translation, but rotates by a thermal motion. This relates to the fact that the fullerene has an isotropic ball state in which the bonding between fullerene molecules is weak and the anisotropy of the potential of the bonding is small. Accordingly, the bonding between fullerene molecules in a solid body is mainly van der Waals bonding caused by interaction of .pi. electrons.
Thin films of fullerenes, can be patterned by lithography. Since the fullerenes have a sublimation property and can form a thin film, if a latent image can be formed and developed on this thin film, the fullerene can patterned with photolithography to create an organic electroluminescent display.
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