Metal-semiconductor transition like behavior of naphthalene-doped single wall carbon nanotube bundles.

Naphthalene (N) or naphthalene-derivative (ND) adsorption-treatment evidently varies the electrical conductivity of single wall carbon nanotube (SWCNT) bundles over a wide temperature range due to a charge-transfer interaction. The adsorption treatment of SWCNTs with dinitronaphthalene molecules enhances the electrical conductivity of the SWCNT bundles by 50 times. The temperature dependence of the electrical conductivity of N- or ND-adsorbed SWCNT bundles having a superlattice structure suggests metal-semiconductor transition like behavior near 260 K. The ND-adsorbed SWCNT gives a maximum in the logarithm of electrical conductivity vs. T(-1) plot, which may occur after the change to a metallic state and be associated with a partial unravelling of the SWCNT bundle due to an evoked librational motion of the moieties of ND with elevation of the temperature.