Browsing by Author "Motaung, David"

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    Annealing effect of hybrid solar cells based on poly (3-hexylthiophene) and zinc-oxide nanostructures
    (Elsevier, 2013) Motaung, David; Malgas, Gerald; Ray, Suprakas S.; Arendse, Christopher
    The structural growth and optical and photovoltaic properties of the organic–inorganic hybrid structures of zinc oxide (ZnO)-nanorods/poly-3-hexylthiophene (P3HT) and two variations of organic polymer blends of ZnO/ P3HT:C60 fullerene and ZnO/P3HT:6,6]-phenyl C61 butyric acid methyl ester were studied in detail during thermal annealing. The ordering of the P3HT nanocrystals increased during annealing, which also improved hole transport in the hybrid structures. The optical constants of the ZnO/P3HT:[6,6]-phenyl C61 butyric acid methyl ester (PCBM) films elevated with annealing temperature due to the improved crystallisation induced by the formation of P3HT crystalline domains. As a result, a maximum power conversion efficiency of approximately 1.03% was achieved for the annealed ZnO/P3HT:PCBM device at 140 °C. These findings indicate that ZnO-nanorods/P3HT:PCBM films are stable at temperatures up to 160 °C.
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    Self-catalytic growth of tin oxide nanowires by chemical vapor deposition process
    (Hindawi, 2013) Thabethe, Bongani; Malgas, Gerald; Motaung, David; Malwela, Thomas; Arendse, Christopher
    We report on the synthesis of tin oxide (SnO2) nanowires by a chemical vapor deposition (CVD) process. Commercially bought SnO nanopowders were vaporized at 1050∘C for 30 minutes with argon gas continuously passing through the system. The assynthesized products were characterized using UV-visible absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The band gap of the nanowires determined from UV-visible absorption was around 3.7 eV.The SEM micrographs revealed “wool-like” structure which contains nanoribbons and nanowires with liquid droplets at the tips. Nanowires typically have diameter in the range of 50–200nm and length 10–100 𝜇m. These nanowires followed the vapor-liquid-solid (VLS) growth mechanism.
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    Visible and IR photoluminescence of c-FeSi@a–Si core–shell nano-fibres produced by vapour transport
    (Elsevier, 2013) Thabethe, Sibongiseni; Linganiso, Ella; Motaung, David; Mashapa, Matete G.; Nkosi, Steven; Arendse, Christopher; Mwakikung, Bonex W.
    The procedures for the synthesis of amorphous ε-FeSi/Sicore–shell nanofibres by vapour transport in a CVD configuration are reported. Crystallite studies by the Williamson-Hall method show the sizes to be typically about 8.0nm which agrees with TEM value of 7.9nm fibre diameter with a compressive strain of about 0.04. Features in the photoluminescence of these FeSi core–shells in both visible and IR are at 410nm,1062nm,1414nm and 1772nm and absorption feature at 1000cm−1 from FTIR are explained from density functional theory(DFT) abinitio calculations. PL confirms the intra-band transition whereas FTIR agrees perfectly with the band-to-band transition whose band gap energy is 0.13eV for FeSi. FTIR also unveils inter-bandtransition which DFT calculation could not predict. Raman spectroscopy data confirm FeSi and nano-Sipresence.