Muhammad Mat Salleh

Solution-Processed Ga-Doped ZnO Nanorod Arrays as Electron Acceptors in Organic Solar Cells

This paper reports the utilization of ZnO nanorod arrays (NRAs) doped with various concentrations of Ga (0, 0.5, 1, 2, and 3 at %) as electron acceptors in organic solar cells. The donor, poly(3-hexylthiophene) (P3HT), was spin coated onto Ga-doped ZnO NRAs that were grown on fluorine-doped tin oxide (FTO) substrates, followed by the deposition of a Ag electrode by a magnetron sputtering method. Adjusting the Ga precursor concentration allowed for the control of the structural and optical properties of ZnO NRAs. The short circuit current density increased with increasing Ga concentration from 0 to 1 at %, mainly because of improved exciton dissociation and increased charge extraction. Meanwhile, the reduced charge recombination and lower hole leakage current led to an increase in the open circuit voltage with Ga concentrations up to 1 at %. The device with the optimum Ga concentration of 1 at % exhibited power conversion efficiency nearly three times higher compared to the device without Ga doping. This finding suggests that the incorporation of Ga can be a simple and effective approach to improve the photovoltaic performance of organic solar cells.

Chicken dung biogas power generating system in Malaysia

A study on the possibility of developing biogas power generating system from layers farming is presented. The farm consists of 300,000 heads of layer producing 9000 kg/day dry weight of the chicken dung. The gas will be used in a combined heat and power system to meet the energy requirements of the farm. The solid residue from the biogas digestor will be sold as fertiliser. It is envisaged that this study will promote wider application of the system in Malaysia.

Electrical characterization of reduced graphene oxide deposited on interdigitated electrodes

Nowadays, reduced graphene oxide (rGO) has been used in many applications because the surface defect density can be controlled compared to pristine graphene. It has a band gap which make it easier to integrate with existing technologies. Though, a simple process and large scale device fabrication is needed to align the rGO during fabrication of device. In this work, dielectrophoresis (DEP) technique has been used to align the rGO on a substrate with interdigitated electrodes. First, the rGO was drop-casted on sample with interdigitated electrodes. Followed by DEP process to align the deposited rGO. Electrical measurement has been done. It shows that the conductivity and current increases with the increased number of drops for rGO solution. SEM image shows a distribution pattern which forms percolation network pathway of rGO. Raman spectroscopy confirmed the presence of rGO in between the channel of electrodes. This simple technique has the potential to be used for future large scale device fabrication.

Deposition of Au/TiO2 nanocomposite on ITO surface by seed-mediated liquid phase deposition method

An efficient, simple and new procedure has been performed to synthesis Au/TiO2 nanocomposite thin film on solid surface of ITO by seed-mediated of liquid phase deposition (LPD) method. The deposition of Au seed was applied by our previously reported seed-mediated growth procedure. The solution was prepared by mixing HAuCl4 and (NH4)2TiF6 successfully deposited on to ITO substrate containing Au seed. After one hour well adhered film was obtained by mentioned approach of synthesis and nonocomposite with spherical rod like networks has been successfully grown. The resulting nanocomposites were confirmed by ultraviolet-visible (Uv-Vis) absorption spectroscopy. Further characterization and morphology was checked by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD).

2,2′-[2,5-Bis(hex­yloxy)-1,4-phenyl­ene]dithio­phene

The asymmetric unit of the title compound, C26H34O2S2, comprises one half-molecule located on an inversion centre. The thiophene groups are twisted relative to the benzene ring, making a dihedral angle of 5.30 (7)°, and the n-hexyl groups are in a fully extended conformation. In the crystal, there are short C—H⋯π contacts involving the thiophene groups.

Effect of Annealing Temperatures on Formation of Na0.5Bi0.5TiO3 and (Na0.5Bi0.5)0.96Ba0.04TiO3 Ceramics Prepared via Sol Gel Method

The effect of annealing temperatures on the formation of pure perovskite Na0.5Bi0.5TiO3 (NBT) based ceramics prepared by sol gel method has been investigated. The NBT sol was prepared using NaCH3COO, C6H9BiO6 and Ti(C4H9)4 with 2-methoxyethanol and glacial acetic acid were used as solvents. The BaTiO3 sol was synthesized using C4H6BaO4 and Ti(C4H9)4 with acetic acid and ethanolamine were used as solvents. The (Na0.5Bi0.5)0.96Ba0.04TiO3 (NBBT) sol was prepared by mixing appropriate amount of NBT and BaTiO3 sols. Then NBT and NBBT sols were dried at 200oC for 24 h, ground and subsequently annealed at temperatures ranging from 440oC – 640oC for 5 min. Formation of NBT and NBBT ceramics was examined using XRD technique. X-ray diffractograms reveal that the NBT ceramic with rhombohedral structure starts to form at 540oC and complete crystallization is achieved at 620oC. Addition of 4vol% of BaTiO3 sols drastically reduces the crystallization temperature of NBBT ceramic to 460oC and a pure single phase ceramic is achieved at 520oC. Despite retaining the same rhombohedral structure, the NBBT exhibits lattice parameters expansion indicating a successful Ba substitution which is also confirms by the absence of BaTiO3 peaks in the diffractograms. Both ceramics exhibit great thermal stability with additional increment in annealing temperatures.

Characterization of SnO2 Nanoparticles Prepared by Two Different Wet Chemistry Methods

Effects of synthesis techniques, namely sol gel method and direct growth method on the nanostructural and optical properties of SnO2 have been investigated. The XRD results confirmed that both samples are single phase SnO2. The crystallite size of SnO2 prepared by sol-gel and direct growth method were approximately 10 nm and 15 nm respectively. The FE-SEM micrographs displayed that SnO2 nanoparticles prepared by sol gel method exhibited a round shape with approximate particle size of 10 nm while the direct growth method produced SnO2 nanorod with length and width of 570 nm and 55 nm respectively. The direct Eg for both SnO2 nanospheres and nanorods are 3.98 eV and 3.94 eV respectively, Due to quantum confinement effect, both nanomaterials exhibited strong blue shift compared to bulk material with Eg of 3.6 eV.

3,5-Dibromo-2-[2,5-dibut-oxy-4-(3,5-dibromo-thio-phen-2-yl)phen-yl]thio-phene.

The title molecule, C22H22Br4O2S2, is centrosymmetric with an inversion centre located at the centre of the benzene ring. The 3,5-dibromothiophene groups are twisted relative to the benzene ring, making a dihedral angle of 41.43 (9)°.

Enhanced-photoluminescence properties of CdTe quantum dots prepared from the ternary surfactant mixture system

This paper reports the synthesis and characterization of CdTe system in the ternary surfactant mixture. The quantum dots was prepared by quick injection of tri-n-octylphosphine telluride (TOPTe) into reactor that contains a hot mixed cadmium acetate hydrate, 1-octadecene, n-octadecyl phosphoric acid (ODPA), octadecylamine (ODA) and oleic acid (OA). We found that the surfactant of ODPA, OA and ODA were very important for the enhancement at the Photoluminescence (PL) properties CdTe quantum dots.

Facile Approach for Preparing CdSe/CdTe Heterostucture Quantum Dots

This paper reports a simple strategy to synthesize CdSe/CdTe heterostucture Quantum Dots (QDs) via successive injection of selenium and tellurium precursors into cadmium precursor at 350° C. In typical process, it was found that the heterostucture QDs exhibited a totally new absorption and photoluminescence (PL) properties that are different from individual CdSe and CdTe properties. For example, its PL emissions Quantum Yield (QY) were triple of CdSe and five times of CdTe high quantum QY, the heterostucture QDs should be potential used in LED and solar cell applications.