Browsing by Author "Ramoroka, Morongwa Emmanuel"

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    Novel aromatic dendritic-co-poly(3-hexylthiophene) composites for photovoltaic cell application
    (University of Western Cape, 2021) Ramoroka, Morongwa Emmanuel; Iwuoha, Emmanuel I.
    Fossil fuels are part of fuels that are formed from natural processes and they are called non-renewable sources of energy. These include natural gas, coal and oil. They have been used for decades to produce energy globally. However, there are some factors that related with the use of fossil fuels which results in an increase in the requirement of large amounts of energy. In addition, the use of fossil fuels as energy source has a negative impact on the environment and they cannot be reused. It is expected that at some point they will run out. Thus, a need for a renewable, clean and plentiful source of energy is urgent. Solar energy is one of the energy sources that may overcome fossil fuel drawbacks.
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    Novel heterojunction superstrate Cu2ZnInS4−x (CZIS) thin film kesterite solar cell with vertical arrays of hexagonal ZnO nanorods window layer
    (Elsevier, 2022-11-24) Yussuf, Sodiq Tolulope; Ramoroka, Morongwa Emmanuel; Mdluli, Siyabonga Beizel; Nwambaekwe, Kelechi Chiemezie; Ekwere, Precious Idinma; Uhuo, Onyinyechi Vivian; Ikpo, Chinwe Oluchi; Iwuoha, Emmanuel Iheanyichukwu
    Quaternary Cu2ZnInS4−x (CZIS) thin films have been prepared by a facile and cheap sol-gel spin coating technique. Low-temperature solution-based methods were used to fabricate a heterojunction solar cell in the superstrate architecture with CZIS thin film as the absorber, vertically aligned ZnO nanorod arrays, and CdS as the window and buffer layers respectively. ZnO nanorod arrays were prepared by hydrothermal technique and nanocrystal layer deposition technique were employed for the deposition of CdS-coated ZnO nanorod arrays. CZIS absorber layer was spin coated on the CdS-coated ZnO nanorod arrays and annealed at different temperatures. The vertically aligned ZnO nanorod arrays, and uniformly distributed CdS shell layer were confirmed from morphological studies. The device had a final configuration of Glass/ITO/ZnO NRs/CdS/ CZIS/Ag. HRSEM revealed a nanoflake-like morphology and a band gap between 1.5 and 1.77 eV for the CZIS thin films. CZIS superstrate solar cell had a power conversion efficiency of ∼ 0.61%, an open circuit voltage of ∼ 0.8 V, a short circuit current of ∼ 0.95 mA cm−2 and a fill factor of ∼ 61.35%. This method demonstrates a novel, facile and eco-friendly technique for synthesizing nanocrystalline CZIS thin films with promising photo response from the fabricated device indicating a proof of principle that this material can find application in solar cells.
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    Photophysics of Thiophenosalicylaldimine-functionalized G1-Polyprolyleniminato-Copper Telluride/Antimonide core-shell Nanomaterials
    (University of the Western Cape, 2018) Ramoroka, Morongwa Emmanuel; Iwuoha, Emmanuel I
    This work involves the synthesis of copper telluride-polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (CuTe@PPI) and copper antimonide-polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (CuSb@PPI) core-shell nanoparticles (NPs), using two-pots and one-pot synthesis methods, respectively. Their morphology was studied by X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM) and high resolution scanning electron microscopy (HRSEM); while their structures were characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis. Photophysical properties of the core-shell NPs were determined from ultraviolet-visible absorption spectroscopy (UV-Vis) and photoluminescence spectroscopy (PL). For core-shell NPs produced via two-pots method only CuTe@PPI exhibited ? ? ?* and n ? ?* which indicate that CuSb@PPI produced via two-pots method was unsuccessfully synthesized. The ? ? ?* and n ? ?* transitions indicate the presence of polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (PPI) on the surface of CuTe NPs and CuSb NPs. FTIR confirmed coordination of PPI on the surface of CuTe NPs and CuSb NPs by showing a shift in wavenumber of C=N group bands from PPI. HR-TEM showed that the CuTe@PPI synthesized via one-pot method have a wide particles sizes distribution with an average particles size of 13.60 nm while for CuTe@PPI synthesized via two-pots it was impossible to determine the particles size due to aggregation. CuSb@PPI synthesized via twopots method and one-pot method has a wide particles sizes distribution with an average size of 7.98 nm and 11.61 nm respectively. The average particles sizes determined by HR-SEM were found to be 35.24 nm (CuTe@PPI two-pots method), 33.90 nm (CuTe@PPI one-pot method), 18.30 nm (CuSb@PPI two-pots method), and 16.18 nm (CuSb@PPI one pot method).