Switchable semiconductive property of the polyhydroxylated metallofullerene.
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.
Tang
Jun
J
Lab for Bio-Environmental Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
Xing
Gengmei
G
Zhao
Yuliang
Y
Jing
Long
L
Yuan
Hui
H
Zhao
Feng
F
Gao
Xueyun
X
Qian
Haijie
H
Su
Run
R
Ibrahim
Kurash
K
Chu
Weiguo
W
Zhang
Lina
L
Tanigaki
Katsumi
K
D004553:Electric Conductivity; D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D010777:Photochemistry; D013696:Temperature; D014867:Water / Q000737:chemistry*
D037741:Fullerenes; D014867:Water; D006046:Gold