Charge carrier behavior in UV irradiated fullerene nano whiskers based on studies of electrical conduction and ESR

The UV light irradiation to C ₆₀ fullerene induces [2+2] cyclo-additional reaction, and creates inter-molecule bonds between C ₆₀ molecules. That reaction makes fullerene polymer from molecules. A fine crystalline wire structure consisting of C ₆₀ molecules is called a fullerene nano whisker (FNW), and also is used to fabricate n-type field effect transistors (FET) as the channel. The UV irradiation to the FNW-FET for polymerization must achieve the FET operation in ambient atmosphere. Here, a drastic changing of FET parameters has been observed. In the ESR measurement in ambient atmosphere, we have studied on temperature dependence of peak-to-peak width (ΔHPP) and ESR magnetic susceptibility ratio. The comparison, the temperature dependence of pristine FNW and UV irradiated FNW, clearly indicates that there exists a clearer difference in electronic state between pristine FNW and UV polymerized FNW.