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221.
P.G. Hugger J.D. Cohen Baojie Yan Jeffrey Yang Subhendu Guha 《Journal of Non》2008,354(19-25):2460-2463
The electronic properties of hydrogenated nanocrystalline silicon (nc-Si:H) were studied using drive-level capacitance profiling (DLCP) to obtain defect density profiles as well as transient photocapacitance (TPC) and transient photocurrent (TPI) spectroscopies to study the spectra of defect related optical transitions. These measurements were performed on a series of n–i–p solar cell devices with intrinsic layer thickness of roughly 1 μm. The nc-Si:H intrinsic layers were deposited using RF or MVHF glow discharge with various hydrogen dilution profiles predominantly on specular stainless steel substrates (SS/n+/i nc-Si:H/p+/ITO), but also on textured back reflectors (SS/Ag/ZnO/n+/i nc-Si:H/p+/ITO) in some cases. Crystallite fractions were estimated using Raman spectroscopy. The electronic properties determined by our measurements could be correlated with variations in structural device parameters and with the degree of hydrogen dilution profiling during growth. We also found, depending on the growth conditions, that the devices exhibited markedly different behaviors after prolonged light exposure (100 h using light at 610 nm and 500 mW/cm2 intensity). We discuss one specific microscopic mechanism that may be responsible for the light-induced changes that we have observed. 相似文献
222.
Michael G. B. Drew Debashree Das Senjuti De Jnan Prakash Naskar Dipankar Datta 《Journal of chemical crystallography》2008,38(7):507-512
Abstract The X-ray crystal structure of the 1:2 condensate (1) of hydrazine hydrate and 4-methyl-imidazole-5-carboxaldehyde has been
determined. The molecule is centrosymmetric crystallising in the space group Fddd with cell dimensions: a = 10.557(14), b = 17.062(22), c = 24.759(27) ?. Fourier map shows that the NH hydrogen atom of each imidazole moiety has equal possibility of occupying any
of its two ring N atoms. This poses the possibility of finding three tautomers in 1 in the solid state. Consideration of the H-bonding pattern observed in 1 and related B3LYP/6-311+G(2d,p) calculations show that only two tautomers are present in the solid state. The situation is
compared with that in the structure of 4(5)-nitro-5(4)-methoxy-imidazole reported previously by Kubicki.
Graphical Abstract
The inherent disorder of the ring N–H hydrogen atoms in the shown centrosymmetric molecule (blue, C; deep blue, N; grey, H)
which contains two imidazole moieties, poses the possibility of the coexistence of three tautomers in the solid state. The
observed and theoretical [from B3LYP/6-311+G(2d,p) calculations] H-bonding pattern indicate that only two tautomers are present
in the solid state.
相似文献
223.
Amit Basak Subhendu Sekhar Bag Kakali Rani Rudra Jharna Barman Sumana Dutta 《ChemInform》2002,33(48):115-115
224.
Bimetallic palladium(II) complexes containing classical NHC donor ligands are becoming increasingly popular owing to their various catalytic applications. However, examples of the aforementioned complexes with mixed NHC/PPh3 ligands are still rare. Bimetallic palladium(II) complexes possessing these mixed ligands are described starting from a C2-symmetric bis-imidazolium salt containing 4,4′-substituted central biphenyl ring. All the palladium(II) complexes have been tested as precatalysts in α-arylation of oxindole and Suzuki–Miyaura coupling reactions. The complex composed of mixed NHC/PPh3 donor ligands shows superior catalytic activity compared with the corresponding PEPPSI type complexes when applied in α-arylation of oxindole. The dinuclear complexes display better activity compared with the mononuclear complexes. The preliminary electrochemical measurements show the facile oxidation of PdII in the presence of combined NHC/PPh3 ligands compared with a combination of NHC/Py ligands. 相似文献