Abstract:The sulpbospinels reported in the title, with x ranging from 0 to 1.0, were characterized by bulk and surface techniqnes (XRD, magnetic susceptibility, reflectance spectroscopy and XPS, including x-ray induced Auger SPeetr~OPY).Homogeneous spinel solid solutions are formed up to x = 0.4, whereas for the other compositions the CuInS, Only monovalent copper was found in aU the samples, in the bulk as well as on the surface.The surface of the solphospinels is stable to air; on the contrary, the surface of CuS is … Show more
“…Only one sulfur species is observed. The binding energy of 161.8 eV ± 0.1 eV for the 2p 3/2 sublevel is in good agreement with the binding energy of the S 2p 3/2 level measured in bulk CdS. , Neither is it possible in our spectra to distinguish between S in CdS and in HgS nor can a distinct surface environment be seen. 5 High resolution spectrum of the S 2p core level of CdS/HgS/CdS nanocrystals at a surface sensitive energy.…”
Colloidally prepared CdS/HgS/CdS quantum dot quantum well nanocrystals and CdS/HgS/CdS/HgS/CdS double quantum well nanocrystals stabilized with polyphosphates have been investigated by photoelectron spectroscopy with tuneable synchrotron radiation. High-resolution spectra reveal in addition to a bulk species also a surface environment for Cd, whereas different S species could not be resolved. Although not expected for the ideal structure model, Hg occurs in two distinct environments. The total amount of Hg giving evidence for sample inhomogeneities is of the order of 10%. Furthermore, to some extent, the XPS experiments allowed characterization of the onion like structure of the quantum dot quantum well nanocrystals. A method for layer thickness determination previously developed for core shell nanocrystals is extended to the more complex case of quantum dot quantum well structures.
“…Only one sulfur species is observed. The binding energy of 161.8 eV ± 0.1 eV for the 2p 3/2 sublevel is in good agreement with the binding energy of the S 2p 3/2 level measured in bulk CdS. , Neither is it possible in our spectra to distinguish between S in CdS and in HgS nor can a distinct surface environment be seen. 5 High resolution spectrum of the S 2p core level of CdS/HgS/CdS nanocrystals at a surface sensitive energy.…”
Colloidally prepared CdS/HgS/CdS quantum dot quantum well nanocrystals and CdS/HgS/CdS/HgS/CdS double quantum well nanocrystals stabilized with polyphosphates have been investigated by photoelectron spectroscopy with tuneable synchrotron radiation. High-resolution spectra reveal in addition to a bulk species also a surface environment for Cd, whereas different S species could not be resolved. Although not expected for the ideal structure model, Hg occurs in two distinct environments. The total amount of Hg giving evidence for sample inhomogeneities is of the order of 10%. Furthermore, to some extent, the XPS experiments allowed characterization of the onion like structure of the quantum dot quantum well nanocrystals. A method for layer thickness determination previously developed for core shell nanocrystals is extended to the more complex case of quantum dot quantum well structures.
“…33,34 Similarly the sulphur present in the CIS is in agreement with the literature values for S 2À . 35 These oxidation states reflect a neutral stoichiometric CIS product.…”
Copper indium disulphide (CIS) nanocrystals (NCs) were prepared using a one-pot synthesis. The stoichiometry was optimized based on its current density as measured by photoelectrochemical (PEC) experiments at interfaces between NC films deposited on ITO and 0.1 M methyl viologen dichloride (MV(2+)) solution. This method also offers insight into the kinetics of the photoreaction. A copper poor sulphur rich starting ratio was found to produce a copper-rich, indium-poor and slightly sulphur rich material. Further NC characterization was performed with SEM and TEM to investigate the morphology and crystallinity of the 30-70 nm NCs. The oxidation states of the individual elements were determined to be I, III, and 2- for Cu, In and S, respectively. Characteristics of optimal as-prepared NCs were found to be compatible among high functioning absorbing layers.
“…The S 2p photoelectron peak lies at 162.4 eV, also in the vicinity of the BE values characteristic of CdS [15,16]. The sample composition indicates an enrichment of the film surface by sulphur (S:Cd = 1.24), with respect to the CdS stoichiometry.…”
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