Tang J, Xing G, Zhao Y, Jing L, Yuan H, Zhao F, Gao X, Qian H, Su R, Ibrahim K, Chu W, Zhang L, Tanigaki K. Switchable Semiconductive Property of the Polyhydroxylated Metallofullerene.
J Phys Chem B 2007;
111:11929-34. [PMID:
17892281 DOI:
10.1021/jp074863r]
[Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The temperature-sensitive property of polyhydroxylated metallofullerene film of Gd@C82(OH)x with special hydroxyl number was studied using synchrotron radiation ultraviolet photoelectron spectroscopy (UPS) and TEM techniques. From room temperature (RT) to 4 degrees C the photoelectron onset energy of the spectra of Gd@C82(OH)12 shifted from 1.9 to 0.2 eV, indicating that Gd@C82(OH)12 automatically shifted from insulator at RT to semiconductor at 4 degrees C. However, this could not be observed for Gd@C82(OH)20. TEM experiments show that the variation of conductivity can be ascribed to formation of a microcrystal under low temperature. The dipole moment induced unique intermolecular interactions and self-assembled microcrystalline structures for Gd@C82(OH)12. This may cause reconstruction of the upper valence band formed by pi-like electrons as well as the density of states (DOS) around the Fermi level (EF) and reconstruct the deeper valence band formed by sigma-like electrons, eventually resulting in a shift to a semiconducting nature. These findings revealed a novel nature for polyhydroxylated Gd@C82(OH)x materials: Their insulating properties can be controllably tuned into semiconducting ones as a function of temperature.
Collapse