A perylene bisimide dye covalently bonded with a hydrogen-bond formation group of 1, 3, 5-triazine-2, 4-diamine has been synthesized. Its casting films show a charge carrier mobility over 10^-3 cm^2/Vs, which is in th...A perylene bisimide dye covalently bonded with a hydrogen-bond formation group of 1, 3, 5-triazine-2, 4-diamine has been synthesized. Its casting films show a charge carrier mobility over 10^-3 cm^2/Vs, which is in the range of the highest values found for other promising charge transport materials suitable for solution processable technique.展开更多
We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yi...We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yield, respectively.展开更多
Group-Ⅳ tellurides have exhibited exotic band structures.Specifically,despite the fact that Sn sits between Ge and Pb in the same column of the periodic table,cubic SnTe is a topological crystalline insulator with ba...Group-Ⅳ tellurides have exhibited exotic band structures.Specifically,despite the fact that Sn sits between Ge and Pb in the same column of the periodic table,cubic SnTe is a topological crystalline insulator with band inversion,but both isovalent GeTe and PbTe are trivial semiconductors with normal band order.By performing first-principles band structure calculations,we unravel the origin of this abnormal behaviour by using symmetry analysis and the atomic orbital energy levels and atomic sizes of these elements.In group-Ⅳ tellurides,the s lone pair band of the group-Ⅳ element is allowed by symmetry to couple with the anion valence p band at the L-point,and such s–p coupling leads to the occurrence of bandgap at the L-point.We find that such s–p coupling is so strong in SnTe that it inverts the band order near the bandgap;however,it is not strong enough in both GeTe and PbTe,so they remain normal semiconductors.The reason for this is the incomplete screening of the core of the relatively tight-binding Ge 4s orbital by its 3d orbitals and the large atomic size and strong relativistic effect in Pb,respectively.Interestingly,we also find that the rhombohedral distortion removes the inversion symmetry and the reduced s–p coupling transforms theα-SnTe back to a normal semiconductor.Our study demonstrates that,in addition to spin–orbital coupling,strain and interface dipole fields,inter-orbital coupling is another effective way to engineer the topological insulators.展开更多
基金This research was supported by the National Natural Scientific Foundation of China(No.90101008)973 project(No.2002CB613401)of the MST of P.R.China.
文摘A perylene bisimide dye covalently bonded with a hydrogen-bond formation group of 1, 3, 5-triazine-2, 4-diamine has been synthesized. Its casting films show a charge carrier mobility over 10^-3 cm^2/Vs, which is in the range of the highest values found for other promising charge transport materials suitable for solution processable technique.
基金supported by the National Natural Science Foundation of China(Grant No.50073018 and 90101008)
文摘We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yield, respectively.
基金supported by Natural Science Foundation of China(No.61290305,11374259,11374293 and 61474116)supported by the National Young 1000 Talents Planfunded by the US Department of Energy,under Contract No.DE-AC36-08GO28308.
文摘Group-Ⅳ tellurides have exhibited exotic band structures.Specifically,despite the fact that Sn sits between Ge and Pb in the same column of the periodic table,cubic SnTe is a topological crystalline insulator with band inversion,but both isovalent GeTe and PbTe are trivial semiconductors with normal band order.By performing first-principles band structure calculations,we unravel the origin of this abnormal behaviour by using symmetry analysis and the atomic orbital energy levels and atomic sizes of these elements.In group-Ⅳ tellurides,the s lone pair band of the group-Ⅳ element is allowed by symmetry to couple with the anion valence p band at the L-point,and such s–p coupling leads to the occurrence of bandgap at the L-point.We find that such s–p coupling is so strong in SnTe that it inverts the band order near the bandgap;however,it is not strong enough in both GeTe and PbTe,so they remain normal semiconductors.The reason for this is the incomplete screening of the core of the relatively tight-binding Ge 4s orbital by its 3d orbitals and the large atomic size and strong relativistic effect in Pb,respectively.Interestingly,we also find that the rhombohedral distortion removes the inversion symmetry and the reduced s–p coupling transforms theα-SnTe back to a normal semiconductor.Our study demonstrates that,in addition to spin–orbital coupling,strain and interface dipole fields,inter-orbital coupling is another effective way to engineer the topological insulators.
