Picene, which attracts the great interest of researchers, not only can be used to fabricate thin film transistors with high hole mobilities, but also is the parent material of a new type organic superconductor. Here, ...Picene, which attracts the great interest of researchers, not only can be used to fabricate thin film transistors with high hole mobilities, but also is the parent material of a new type organic superconductor. Here, we investigate the electronic properties of individual picene molecules directly adsorbed on Cu（111） surface by a combination of experimental scanning tunneling microscopy/spectroscopy measurements and theoretical calculations based on the density functional theory. At low coverage, the picene molecules exhibit mono-dispersed adsorption behavior with the benzene ring planes parallel to the surface. The highest occupied state around -1.2 V and the lowest unoccupied state around 1.6 V with an obvious energy gap of the singly adsorbed picene molecule are identified by the dI/dV spectra and maps. In addition, we observe the strong dependence of the dI/dV signal of the unoccupied states on the intramolecular positions. Our first-principles calculations reproduce the above experimental results and interpret them as a specific molecule-substrate interaction and energy/spatial distributions of hybrid states mainly derived from different molecular orbitals of picene with some intermixing between them. This work provides direct information on the local electronic structure of individual picene on a metallic substrate and will facilitate the understanding the dependence of electron transport properties on the coupling between molecules and metal electrodes in single-molecule devices.展开更多
In order to investigate the non-bonded interaction between picene and B12 N12 nano ring(BNNR) in different orientations and distances, we focused on a single-wall boronnitride B12 N12 nano-ring. The geometry of molecu...In order to investigate the non-bonded interaction between picene and B12 N12 nano ring(BNNR) in different orientations and distances, we focused on a single-wall boronnitride B12 N12 nano-ring. The geometry of molecules was optimized using the B3 LYP method with 6-31 g* basis set. The reactivity and stability of picene as an aromatic compound alone and upon exposure to BNNR were checked. Then NBO, FREQ, NICS and adsorption energy of picene alone and in the presence of BNNR Field were derived to estimate the picene structural stability.The results of any order were found to reduce the reactivity and increase the stability for picene in the presence BNNR field.展开更多
基金This work was supported by the National Basic Research Program of China （No.2011CB921400）, the Strategic Priority Research Program （B） of the Chinese Academy of Sciences （No.XDB01020100）, the Key Research Program of the Chinese Academy of Sciences （No.KJCX2-EWJ02）, the Youth Innovation Promotion Association of the Chinese Academy of Sciences （No.2011322）, and the National Natural Science Foundation of China （No.21473174, No.21273210, and No.51132007）.
文摘Picene, which attracts the great interest of researchers, not only can be used to fabricate thin film transistors with high hole mobilities, but also is the parent material of a new type organic superconductor. Here, we investigate the electronic properties of individual picene molecules directly adsorbed on Cu（111） surface by a combination of experimental scanning tunneling microscopy/spectroscopy measurements and theoretical calculations based on the density functional theory. At low coverage, the picene molecules exhibit mono-dispersed adsorption behavior with the benzene ring planes parallel to the surface. The highest occupied state around -1.2 V and the lowest unoccupied state around 1.6 V with an obvious energy gap of the singly adsorbed picene molecule are identified by the dI/dV spectra and maps. In addition, we observe the strong dependence of the dI/dV signal of the unoccupied states on the intramolecular positions. Our first-principles calculations reproduce the above experimental results and interpret them as a specific molecule-substrate interaction and energy/spatial distributions of hybrid states mainly derived from different molecular orbitals of picene with some intermixing between them. This work provides direct information on the local electronic structure of individual picene on a metallic substrate and will facilitate the understanding the dependence of electron transport properties on the coupling between molecules and metal electrodes in single-molecule devices.
基金supported by the Islamic Azad University of Islamshahr
文摘In order to investigate the non-bonded interaction between picene and B12 N12 nano ring(BNNR) in different orientations and distances, we focused on a single-wall boronnitride B12 N12 nano-ring. The geometry of molecules was optimized using the B3 LYP method with 6-31 g* basis set. The reactivity and stability of picene as an aromatic compound alone and upon exposure to BNNR were checked. Then NBO, FREQ, NICS and adsorption energy of picene alone and in the presence of BNNR Field were derived to estimate the picene structural stability.The results of any order were found to reduce the reactivity and increase the stability for picene in the presence BNNR field.
