Advanced Materials Research Vol. 667

Abstract: The development of reliable and eco-friendly metallic nanoparticles needs some consideration on the chemical procedures involved in the synthesis of nanomaterials. The conventional methods in the production of metallic nanoparticles generate a large amount of hazardous byproducts. Thus, there is a need for ‘green chemistry’ that includes a clean, nontoxic and environment-friendly method of nanoparticle synthesis [1]. As an alternative, biological methods are considered safe and ecologically sound for the nanomaterial fabrication [2]. Therefore, in this review special attention is focused on the biosynthesis of nanoparticles from natural resources as compared as ordinary chemical method. Biosynthesis of nanoparticles using plant is a new development of green nanotechnology beneficial to environmental and to the plant itself. It also plays a significant role in the field of biology and medicine.

Abstract: This paper reported the effect of silane on the electrical properties of the nanocomposite poly(methyl methacrylate): titanium dioxide (PMMA:TiO2) films. Different types of silane were added directly into the nanocomposite PMMA:TiO2 solution. Electrical properties result shows that when different silane were use in the nanocomposite solution give different electrical properties. Sample 1 (without silane) and 4 (trimethoxymethylsilane) shows the highest resistivity and lowest leakage current density. Meanwhile sample 3 (triethoxyvinylsilane) indicate that are not a suitable silane to be added into the nanocomposite PMMA:TiO2 solution because it produce poor insulator behavior.

Abstract: This work focus on optical band gap of nanocomposited MEH-PPV:CNTs thin film. In this research we investigate the behavior of optical band gap when the composition of CNTs powder is increased which directly influence the thickness of the thin film. The experimental process entailed for the black powder of CNTs to be first annealed at 450 °C before mixing it with the polymer solution to ensure that the impurities in the CNTs are all removed. The 20 mg MEH-PPV polymer was dissolved in an aromatic solvent which is toluene with a concentration of 1:1. The composite materials were prepared by adding appropriate amounts of CNTs powder (1, 2, 3 and 4 wt%) into the polymer solution to make various ratios of CNTs powder/polymer composites. The optical properties of the thin film were analyzed by using Perkin Elmer Lambda 750 UV/Vis Spectrometer. Thickness of the thin film is measured using Surface profiler Veeco Dektak 150. In this paper, the optical band gap energy is derived by assuming a direct transition of electron between the edge of the valence band and the conduction band. Our results demonstrates that as the thickness decrease from 62, 60, 59, 58 and 57 nm, the optical band gap showed slight decrement from 2.07, 2.07, 2.05, 2.01 and 2.00 eV for respectively.

Abstract: Nanostructured ZnO as a seeded was prepared by sol-gel technique on p-type silicon in various low molarities. Zinc acetate, Diethanolamine (DEA), and isopropyl were use as starting material, stabilizer, and solvent respectively. Atomic Force Microscopy (AFM) analysis shows smooth surface and uniform layer were produced in low molarities of precursor. The surface morphology of nanostructured ZnO was analyzed by Field Emission Scanning Electron Microscopic (FESEM). It is found that the nanostructured ZnO were successfully deposited on the silicon substrate with size ~10 nm to ~35 nm. Photoluminescence spectroscopy was employed to study the band gap in room temperature. It shows that very low intensity of PL in 0.05m and 0.1 m. PL intensity become more obvious starting from 0.15 m of precursor concentration.

Abstract: The optical properties and morphology of Aluminum (Al) doped Zinc Oxide (ZnO) thin films prepared by sol-gel method have been investigated. The thin films were prepared at annealing temperature of 550 OC and have been exposed under wet and dry conditions. UV-Vissmeasurements have been carried out to investigate the optical properties while Scanning Electron Microscope (SEM) to investigate morphology. The grain size of films was increased with increased annealing temperature. The average optical transmittance became about 80% in the visible and had sharp ultraviolet absorption edges at 380 nm. The absorption edge analysis revealed that the optical band gap energy for the films was ~ 3.26 eV. The surface morphology in increasing annealing temperature has a big size and less porosity between particles.

Abstract: Carbon nanotubes (CNTs) were unique nanostructured materials composed of single or multiple rolled graphene sheet which usually need expensive sources as a starting material in its preparation. In this paper, new approach of starting material was expected to be commercialized due to its cheaper and renewable properties. Fermented glutinous rice would be optimized before it can be used as starting material in the CNTs preparation. In optimizing the process, a few parameters were considered. One of the important parameters was the amount of inoculums; known as ‘ragi’. This paper showed the effect of inoculums using Fourier Transmission Infrared Spectroscopy (FTIR). The amount was varies depending on percentage of glutinous rice used in the process. The optimum amount of inoculums for nanotechnology application was 3.0% (w/w) of glutinous rice due to the most favorable level of glucose and alcohol after 3 days fermentation. The glucose level decreased whereas alcohol yield was raised when higher inoculums amount were used. The result suggested that sample with inoculums amount of 3.0% (w/w) glutinous rice was the best starting material for nanotechnology application.

Abstract: Iodine doped amorphous carbon (a-C: I) thin films were prepared by using Thermal Chemical Vapor Deposition (CVD) with deposition temperature ranging from 5000C to 7000C. The physical and electrical properties of deposited a-C:I thin films were characterized by Raman spectroscope and Solar Simulator system. The presence of 2 peaks known as Raman D peaks and Raman G peaks ensure the amorphous structure of carbon (C). As deposition temperature increase, the ID/IG ratio shows difference value, which indicates the effects of the temperature towards the a-C: I structures. An ohmic graph was obtained for the IV measurement, and the conductivity varies from 10-4 to 101 Scm-1. The photoresponse was also determined for all samples. As a reference, an undoped a-C thin film was prepared to differentiate the characteristic between a-C and a-C: I.

Abstract: The improvement of sensitivity toward humidity by insertion of buffer layer has been investigated. The insertion of hetero- or homo-buffer layer of zinc oxide (ZnO) thin film before deposition of high quality ZnO had been reported for the growth on highly mismatched substrate. Three samples are characterized with different properties which are as deposited ZnO thin film without buffer layer (as deposited ZnO thin film) , anneal ZnO thin film without buffer layer (ZnO thin film) and anneal ZnO thin film with buffer layer (ZnO/ AZO thin film). The structural properties of ZnO thin film has been characterized field emission scanning electron microscopy (FESEM) JEOL JSM 6701F, atomic force microscope AFM (Park System XE-100) and XRD (Rigaku Ultima IV). The electrical and optical properties has been characterized using 2 point probe I-V measurement (Keithley 2400) and UV-Vis spectrophotometer (JASCO 670) respectively. In this work, we have focused on investigating the humidity sensitivity of ZnO thin film deposited using RF magnetron sputtering (SNTEK RSP 5004-PVD) with and without the buffer layer (Aluminum-doped ZnO (AZO)) for humidity sensor application.

Abstract: Thin film of undoped and doped amorphous carbon has been achieved using the simple thermal CVD system in an ambient gas of Ar and Ar with I2, respectively. The electrical and optical properties of the iodine doped amorphous carbon (a-C:I) thin films were studied. The incorporation of iodine into the amorphous carbon thin film results in increase of electrical conductivity as doping temperature increase up to 400°C, which indicates that doping effect of iodine. Heterojuction is confirmed by rectifying current-voltage characteristics of a-C:I/n-Si junction. The decreasing of optical band gap from 0.54 to 0.25 eV after iodine doping was determined which contribute to induce graphitization in the films. Raman result indicates that sp2 and sp3 bonded carbon atoms were dominated in the both with and without iodine doped thin films.

Abstract: The photovoltaic properties of organic solar cells based on hybrid poly [2-methoxy-5-(2-ethylhexyloxy-p-phenylenevinylen) (MEH-PPV) and anatase titanium dioxide (TiO2) nanoparticles as a function of TiO2 concentration were investigated. Synthesis of TiO2 nanoparticles was performed by sol-gel immerses heated method and been used as a filler in MEH-PPV polymer matrix. The hybrid MEH-PPV: TiO2 solar cells exhibited increased in light absorption and power conversion efficiency than the pristine organic solar cell. By further optimizing the concentration of TiO2 nanoparticles, the short-circuit current of the hybrid MEH-PPV: TiO2 was reached up to 0.004823 (mA/cm2) and the corresponding power conversion efficiency was 0.000378% was obtained under Air Mass 1.5 illumination which was more than 80% higher compared to the device without TiO2 nanoparticles. This indicates by embedded TiO2 nanoparticles in MEH-PPV matrix encouraging the charge transportation in the active layer of organic solar cells device.