36 research outputs found
Thermolectric Materials Based on Intercalated Layered Metallic Systems
A novel thermoelectric material in the form of a unit cell including a first reagent intercalated as a semiconducting layer into a metallic layered host and a method for producing the thermoelectric material are disclosed. The unit cell is characterized by a Seebeck coefficient S of 80-140 μV/K° and an electrical conductivity σ of 103 -104 (Ωcm)-1, as well as a figure of merit Z of about 2×10-3 K-1 at 100° K
Metallic Nanoscale Fibers from Stable Iodine-Doped Carbon Nanotubes
A method of doping involves soaking single-walled carbon nanotubes in molten iodine. Excess physisorbed iodine may then be removed by annealing
Method for electrostatic deposition of graphene on a substrate
A method for electrostatic deposition of graphene on a substrate comprises the steps of securing a graphite sample to a first electrode; electrically connecting the first electrode to a positive terminal of a power source; electrically connecting a second electrode to a ground terminal of the power source; placing the substrate over the second electrode; and using the power source to apply a voltage, such that graphene is removed from the graphite sample and deposited on the substrate
Electroplating of CdTe thin films from cadmium sulphate precursor and comparison of layers grown by 3-electrode and 2-electrode systems
Electrodeposition of CdTe thin films was carried out from the late 1970s using the
cadmium sulphate precursor. The solar energy group at Sheffield Hallam University has carried out
a comprehensive study of CdTe thin films electroplated using cadmium sulfate, cadmium nitrate and
cadmium chloride precursors, in order to select the best electrolyte. Some of these results have been
published elsewhere, and this manuscript presents the summary of the results obtained on CdTe layers
grown from cadmium sulphate precursor. In addition, this research program has been exploring the
ways of eliminating the reference electrode, since this is a possible source of detrimental impurities,
such as K+ and Ag+ for CdS/CdTe solar cells. This paper compares the results obtained from CdTe
layers grown by three-electrode (3E) and two-electrode (2E) systems for their material properties and
performance in CdS/CdTe devices. Thin films were characterized using a wide range of analytical
techniques for their structural, morphological, optical and electrical properties. These layers have
also been used in device structures; glass/FTO/CdS/CdTe/Au and CdTe from both methods have
produced solar cells to date with efficiencies in the region of 5%–13%. Comprehensive work carried
out to date produced comparable and superior devices fabricated from materials grown using
2E system
Electrostatic deposition of graphene in a gaseous environment: A deterministic route to synthesize rolled graphenes?
The synthesis of single-wall carbon nanotubes (SWCNTs) of desired diameters
and chiralities is critical to the design of nanoscale electronic devices with
desired properties.1-6 The existing methods are based on self-assembly, 7-16
therefore lacking the control over their diameters and chiralities. The present
work reports a direct route to roll graphene. Specifically, we found that the
electrostatic deposition of graphene yielded: (i) flat graphene layers under
high vacuum (10-7 Torr), (ii) completely scrolled graphene under hydrogen
atmosphere, (iii) partially scrolled graphene under nitrogen atmosphere, and
(iv) no scrolling for helium atmospheres. Our study shows that the application
of the electrostatic field facilitates the rolling of graphene sheets exposed
to appropriate gases and allows the rolling of any size graphene. The technique
proposed here, in conjunction with a technique that produces graphene
nanoribbons (GNRs) of uniform widths, will have significant impact on the
development of carbon nanotube based devices. Furthermore, the present
technique may be applied to obtain tubes/scrolls of other layered materials
Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001¯) 6 H-SiC
Article discussing research on charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC
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Charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC
Article discussing research on charge transfer equilibria in ambient-exposed epitaxial graphene on (0001) 6 H-SiC