Abstract: Semiconductor and metal carbon nanotubes were studied by scanning tunneling microscopy (STM) and spectral ellipsometry. STM measurements with spatial resolution up to 0.15 nm reveal spatially complicated structure of semiconductor nanotube-substrate interface layer. The measurements also registered graphene nanoclusters with hexagonal rings structure on copper. Quantum mechanical numerical calculations of electron density were performed on a carbon nanotube containing 40 atoms.
Abstract: Recently, we considered the application of carbon nanotubes as the buffer layer between the CdS and Cu (In,Ga)Se2 thin film solar cells. In this work the structure of a p-n heterojunction solar cell is analyzed including the single walled carbon nanotubes as the absorber and CdS as n-type semiconductor window layer. The interface and current-voltage characteristics of this proposed structure are studied exerting the general formulation of the p-n heterojunction solar cells proposed by Fonash. We propose that SWCNTs/CdS heterojunction solar cell can overlap with a main part of the sunlight spectrum leading to improve efficiency and short circuit current. The interesting property of such devices is that the light can inter to the device from the absorber as carbon nanotubes are transparent semiconductor nanostructures. The results of this study can be extended to graphene nanolayers as it has been extensively studied by the PV community in recent years.
Abstract: A nanostructured solar cells consist of a nonporous n-type TiO2 nanoparticles and a p-type semiconductor Cu2ZnSnS4 (CZTS) thin film has been numerically simulated using SCAPS-1D tool. The performed theoretically analysis is compared with the experimental reported data. The band diagram, IV characteristics and quantum efficiency of this structure is considered. The benefit of both TiO2 and CZTS material leads to more than 10% conversion efficiency which is promising between the nanoparticle-based heterojunbctions proposed for PV applications.
Abstract: Zn/Al layered double hydroxide (LDH) intercalated by an anionic phenoxyherbicide guest, 3-(4-methoxypheny) propionate (MPP) were prepared by ion-exchange method. Power XRD and FTIR shows that the MPP phenoxyherbicide were successfully intercalated into the LDH interlayer. The basal spacing for Zn/Al layered double hydroxide-3-(4-methoxyphenyl) propionate nanocomposite (LDH-MPP) was 18.7 Å - 20.5 Å for 0.015 M, 0.025 M, and 0.050 M of MPP, respectively. Thermal analysis shows that the thermal stability of MPP was improved by the intercalation into the LDH interlayer. The results were also supported by elemental analysis and the surface morphology of this nanocomposite.
Abstract: This work reports the synthesis of ‘non-toxic’ polydisperse, low diameter silver nanoparticles (AgNPs). Rooibos extracts at temperatures 25 °C, 30 °C, 50 °C, 70 °C and 90 °C were used. The effect of different extraction temperature on the % yield and nature of the AgNPs were investigated. The characteristics of the ‘green synthesis’ processed AgNPs were evaluated through UV-Vis spectroscopy, high resolution tunnelling microscopy (HRTEM), X-ray diffraction (XRD) and EDX techniques. Results indicated an increase in extraction temperature leads to more polyphenol extraction, increase in the AgNP % yield and greater absorbance. A yellow to brown to dark brown colour change observed during the synthesis indicated AgNPs formation. UV-Vis results indicated the AgNPs surface plasmon peaks at 440, 447, 450, 460 and 489 nm for the 25 °C, 30 °C, 50 °C, 70 °C, 90 °C respectively. SEM results revealed spherical nanosized particles with dense cores and lighter outer region with mean diameters for AgNPs ranged between 4.4-5.8 nm. EDX results indicated prominent Ag peaks at 3.10 keV. XRD results showed vaguely defined amorphous polyol peaks at below 2θ = 27°. The sharp peaks at 2θ = 38°, 45°, 66° and 77° which were assigned as 111, 200, 220 and 321 corresponded to the face-centred cubic crystalline silver phase.