The Electronic Properties of Superatom States of Hollow Molecules and Nanomaterials

【作者】 赵瑾； 丰敏； 黄甜； 胡双林； 郑奇靖； 杨金龙； Hrvoje Petek；

【Author】 Jin Zhao;Min Feng;Tian Huang;Shuanglin Hu;Qijing Zheng;Jinlong Yang;Hrvoje Petek;Hefei National Laboratory for Physical Sciences at Microscale & Department of Physics,University of Science and Technology of China (USTC);Department of Physics and Astronomy,University of Pittsburgh;

【机构】 Hefei National Laboratory for Physical Sciences at Microscale & Department of Physics,University of Science and Technology of China (USTC)； Department of Physics and Astronomy,University of Pittsburgh；

【摘要】 Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals.The strong correlation of electronic wavefunctions with the ionic cores couples the electron and lattice motions,leading to efficient interaction and scattering that degrades coherent charge transport.By contrast,electronic states at high-energy with diffuse molecular orbitals may form nearly free-electron(NFE)bands with density maxima in nonnuclear interstitial voids,which are subject to weaker electron-phonon interaction.The superatom molecule orbital(SAMO)of C60,which is bound to the hollow molecular core,behave as an elegant example.1 Further investigations show SAMOs of C60 are derived from the IP states of graphene,which float above and below the molecular plane and undergo free motion parallel to it.Rolling or wrapping graphene sheet into a nanotube or a fullerene transforms the IP states into diffuse atom-like orbitals that are bound primarily to hollow molecular cores,rather than component atoms.2-5 Later investigations found that flat aromatic molecules like C6F6 and C6H6 also have similar SAMOs.6 For large aggregates formed by fullerenes or carbon nanotubes(CNTs),SAMOs form NFE bands,which potentially have superior properties for electronics.One difficulty for the application of SAMOs is that they typically exist above the frontier orbitals and therefore do not contribute to transport.Different attempts have been tried to stabilize SAMOs to below the Fermi level(EF).Through first principles calculations,we found the NFE bands in bi-layer Janus graphane could be partially occupied as well as tuned by transverse electric field.Also,for CNTs arrays sandwiched between insulators like BN sheet,the intertube NFE states could be stabilized below EF if the CNTs is charged.7-8更多还原

【Abstract】 Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals.The strong correlation of electronic wavefunctions with the ionic cores couples the electron and lattice motions,leading to efficient interaction and scattering that degrades coherent charge transport.By contrast,electronic states at high-energy with diffuse molecular orbitals may form nearly free-electron(NFE)bands with density maxima in nonnuclear interstitial voids,which are subject to weaker electron-phonon interaction.The superatom molecule orbital(SAMO)of C60,which is bound to the hollow molecular core,behave as an elegant example.1 Further investigations show SAMOs of C60 are derived from the IP states of graphene,which float above and below the molecular plane and undergo free motion parallel to it.Rolling or wrapping graphene sheet into a nanotube or a fullerene transforms the IP states into diffuse atom-like orbitals that are bound primarily to hollow molecular cores,rather than component atoms.2-5 Later investigations found that flat aromatic molecules like C6F6 and C6H6 also have similar SAMOs.6 For large aggregates formed by fullerenes or carbon nanotubes(CNTs),SAMOs form NFE bands,which potentially have superior properties for electronics.One difficulty for the application of SAMOs is that they typically exist above the frontier orbitals and therefore do not contribute to transport.Different attempts have been tried to stabilize SAMOs to below the Fermi level(EF).Through first principles calculations,we found the NFE bands in bi-layer Janus graphane could be partially occupied as well as tuned by transverse electric field.Also,for CNTs arrays sandwiched between insulators like BN sheet,the intertube NFE states could be stabilized below EF if the CNTs is charged.7-8更多还原