Structure and transport properties of isomer-separatedC82

Abstract

Structure of isomer-separated crystalline ${\mathrm{C}}_{82}$ has been studied by powder x-ray diffraction with synchrotron radiation. The Rietveld refinement was achieved by assuming a simple cubic lattice (space group $\mathrm{Pa}3\ifmmode\bar\else\textasciimacron\fi{}).$ The ${C}_{2}(a)$ symmetry for the ${\mathrm{C}}_{82}$ molecule was supported in this analysis. Transport properties of thin film of ${\mathrm{C}}_{82}$ have been studied by resistivity measurement. The thin film showed a narrow-gap semiconductorlike behavior with gap energy of 0.43 eV. The field effect transistor (FET) of a ${\mathrm{C}}_{82}$ thin film showed an $n\ensuremath{-}\mathrm{c}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{n}\mathrm{e}\mathrm{l}$ normally-on depletion-type behavior, and the mobility was $1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}{\mathrm{cm}}^{2}{\mathrm{V}}^{\ensuremath{-}1}{\mathrm{s}}^{\ensuremath{-}1}$ whose value was one of the largest \ensuremath{\mu} among normally-on FETs with fullerenes. A hopping transport was found as channel conduction for the ${\mathrm{C}}_{82}$ FET above 150 K.