Valence electronic structure of cross-linkedC60polymers:In situhigh-resolution photoelectron spectroscopic and density-functional studies
Valence electronic structure of cross-linkedC60polymers:In situhigh-resolution photoelectron spectroscopic and density-functional studies
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DOI：
10.1103/physrevb.75.233410
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发表时间：
2007-06
影响因子：
3.7
通讯作者：
J. Onoe;T. Ito;S. Kimura;K. Ohno;Y. Noguchi;S. Ueda
中科院分区：
文献类型：
--
作者：
J. Onoe;T. Ito;S. Kimura;K. Ohno;Y. Noguchi;S. Ueda
When a ${\mathrm{C}}_{60}$ film is irradiated with a $3\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ electron beam, a cross-linked ${\mathrm{C}}_{60}$ polymer is formed and exhibits metallic electron-transport $(I\text{\ensuremath{-}}V)$ properties in air at room temperature [J. Onoe et al., Appl. Phys. Lett. 82, 595 (2003)]. To elucidate the origin of the metallic $I\text{\ensuremath{-}}V$ characteristics of the cross-linked polymer, we examined the valence photoelectron spectra of the polymer using in situ high-resolution ultraviolet photoelectron spectroscopy (UPS) and found that the spectrum for the cross-linked ${\mathrm{C}}_{60}$ polymer came across the Fermi level $({E}_{F})$. To understand the UPS results for the ${\mathrm{C}}_{60}$ polymer, we performed first-principles calculations of the band structure for three kinds of optimized three-dimensional unit cells of one-dimensional (1D) cross-linked ${\mathrm{C}}_{60}$ polymers with a cross-linkage consisting of both six- and seven-membered rings and of five- and eight-membered rings (P58). It was found that one quasi-1D P58 cross-linked ${\mathrm{C}}_{60}$ polymer shows semimetallic properties, which provides one possible explanation of both previous (metallic $I\text{\ensuremath{-}}V$ characteristics) and present (valence photoelectron spectra) experimental results.
When a ${\mathrm{C}}_{60}$ film is irradiated with a $3\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ electron beam, a cross-linked ${\mathrm{C}}_{60}$ polymer is formed and exhibits metallic electron-transport $(I\text{\ensuremath{-}}V)$ properties in air at room temperature [J. Onoe et al., Appl. Phys. Lett. 82, 595 (2003)]. To elucidate the origin of the metallic $I\text{\ensuremath{-}}V$ characteristics of the cross-linked polymer, we examined the valence photoelectron spectra of the polymer using in situ high-resolution ultraviolet photoelectron spectroscopy (UPS) and found that the spectrum for the cross-linked ${\mathrm{C}}_{60}$ polymer came across the Fermi level $({E}_{F})$. To understand the UPS results for the ${\mathrm{C}}_{60}$ polymer, we performed first-principles calculations of the band structure for three kinds of optimized three-dimensional unit cells of one-dimensional (1D) cross-linked ${\mathrm{C}}_{60}$ polymers with a cross-linkage consisting of both six- and seven-membered rings and of five- and eight-membered rings (P58). It was found that one quasi-1D P58 cross-linked ${\mathrm{C}}_{60}$ polymer shows semimetallic properties, which provides one possible explanation of both previous (metallic $I\text{\ensuremath{-}}V$ characteristics) and present (valence photoelectron spectra) experimental results.