■ 외부초청 세미나
일시: 07.7.18(수) 11:00
연사: 차승일 박사 (NIMS)
제목: Rapid & Controlled Fabrication Process for Fullerene 1-D Crystals
Considering the current application of fullerenes in the field of organic semiconductor devices, the highly crystalline or single crystal fullerene nanostructures with controlled shape and size contains some breakthrough forimproved efficiency.Recently, fullerene 1-D nanostructures, including nanowhiskers and nanotubes, become attractive kind of materials since the development of liquid-liquid interface precipitation (LLIP) process and several published results reports the modification of LLIP process in order to obtain fullerene 1-D nanostructures more rapidly. The LLIP process has critical advantage; the fabrication of highly crystalline, even single crystal, fullerene 1-D nanostructures with simple apparatus. However, thefabrication fullerene 1-D structures by LLIP process requires long process time from one day to several days. In order to overcome this drawback, a modified process from conventional LLIP process is suggested. In the modified LLIP process, the nucleation step and growth step were divided. For the nucleation step, saturated fullerene solution is mixed with small amount of alcohols such as 2-propanol or ethanol. For the controlled growth step, the fullerenes in the nucleated solution are precipitated by addition of alcohol, which is injected to the bottom of the solution with controlled flow rate. In this modified process, the shape of the precipitated fullerene crystals is critically dependent on the nucleation steps and the size is dependent on the precipitation rate. By combination of proper nucleation step and growth rate, a well defined fullerene 1-D structures, of 200~500nm width and of hundreds m length can be fabricated within two hours. In addition, the fabricated fullerene 1-D structures can be formed into the free-standing felt which is remarkably mechanical stable, flexible and even foldable.