Conducting films of C60 and C70 by alkali-metal doping
Abstract
The preparation is reported of alkali-metal-doped films of C60 and C70 which have electrical conductivities at room temperature comparable to those attained by n-type doped polyacetylene. The highest conductivities observed in the doped films are: 4 S/cm (Cs/C60), 100 (Rb/C60), 500 (K/C60), 20 (Na/C60), 10 (Li/C60), 2 (K/C70). The doping process is reversed on exposure of the films to the atmosphere. At high doping level, the films become more resistive. The conductivity induced in these films is attributed to the formation of energy bands from the pi orbitals of C60 or C70, which become partially filled with carriers on doping. The smaller alkali metal ions should be able to fit into the interstices in the lattice without disrupting the network of contacts between the carbon spheroids. In the case of C60, this would allow the development of an isotropic band structure, and it is proposed that these materials may constitute the first three-dimensional 'organic' conductors.
- Publication:
-
Nature
- Pub Date:
- March 1991
- DOI:
- 10.1038/350320a0
- Bibcode:
- 1991Natur.350..320H
- Keywords:
-
- Alkali Metals;
- Conducting Polymers;
- Conductivity;
- Polyacetylene;
- Thin Films;
- Doped Crystals;
- Energy Bands;
- Molecular Orbitals;
- Raman Spectra;
- Superconductors;
- Solid-State Physics