Temperature dependence of the conductivity and kinetics of oxygen intercalation ofC70films

Electrical conductivity values of $1.8\times {10}^{-9}$ to $1.8\times {10}^{-13}$ $(\Omega \mathrm{cm}{)}^{-1}$ at 30 °C were found in undoped ${\mathrm{C}}_{70}$ films, and the conductivity is thermally activated with an activation energy of 0.51–0.81 eV and a pre-exponential factor of $0.5(\Omega \mathrm{cm}{)}^{-1}.$ We demonstrated that the conductivity decay due to oxygen intercalation follows $\sigma \mathrm{}\left(t\right)=\sigma {\mathrm{}\left(0\right)t}^{-\alpha },$ where α≪1 when $0<t<t1,$ α⩾1 when $t1<t<t2,$ and 0.5⩽α<1.0 when $t>t2,$ corresponding to three processes of oxygen reaction with the film.