Synthesis of CdTe-CdSe core-shell quantum dots with luminescence in the red

This paper reports on the synthesis and characterization of CdTe-CdSe core-shell quantum dots (QDs) with luminescent from 650 to 720 nm. The QDs were synthesized using a wet-chemical process at a moderate temperature (300 °C) following two-steps process of core and shell synthesis. The photoluminescence characterization on the QDs showed that the QDs emitted light in the range of red regime with quantum yield as high as 37%. Owing to their unique photoluminescence characteristics (high quantum yield and narrow spectrum), the QDs may find a potential application in a variety of applications such as LED, solar cell and bio-labeling

Gold nanoplates for a localized surface plasmon resonance-based boric acid sensor

Localized surface plasmon resonance (LSPR) properties of metallic nanostructures, such as gold, are very sensitive to the dielectric environment of the material, which can simply be adjusted by changing its shape and size through modification of the synthesizing process. Thus, these unique properties are very promising, particularly for the detection of various types of chemicals, for example boric acid which is a non-permitted preservative employed in food preparations. For the sensing material, gold (Au) nanoplates with a variety of shapes, i.e., triangular, hexagonal, truncated pentagon and flat rod, were prepared using a seed-mediated growth method. The yield of Au nanoplates was estimated to be ca. 63% over all areas of the sensing material. The nanoplates produced two absorption bands, i.e., the transverse surface plasmon resonance (t-SPR) and the longitudinal surface plasmon resonance (l-SPR) at 545 nm and 710 nm, respectively. In the sensing study, these two bands were used to examine the response of gold nanoplates to the presence of boric acid in an aqueous environment. In a typical process, when the sample is immersed into an aqueous solution containing boric acid, these two bands may change their intensity and peak centers as a result of the interaction between the boric acid and the gold nanoplates. The changes in the intensities and peak positions of t-SPR and l-SPR linearly correlated with the change in the boric acid concentration in the solution

FABRICATION OF ORGANIC LIGHT EMITTING DIODES (OLEDs) FOR FLAT PANEL DISPLAYS

Organic light emitting diodes (OLEDs) are thin film devices in which organic materials are sandwiched between two electrodes. These devices emit light when electricity is passed through them. OLEDs have gained much attention because their potential applications to full color flat panel displays. Generally, OLEDs are assembled using an heterojunction architecture between three or more organic molecular materials: an electron injection layer, the emitting one and finally the hole injection layer. There are two types of OLED devices, depend on the type of molecular materials used in the devices. The first type is Small Molecule OLED. The production of small-molecule OLEDs require vacuum deposition. The second type is Light-Emitting Polymer. In this technology, the organic thin films can be deposited by spin coating or by a technique derived from commercial inkjet printing. This paper discusses the fabrication of both types of OLEDs. A small molecule blue organic light emitting diode was fabricated using thermal evaporation system with ITO/2-TNATA/NPB/DPVBi:dopant/ Alq3/LiF/Al structure, where the emitting molecules is 4,4’-bis(2,2’-diphenylvinyl)-1,1’-biphenyl (DPVBi). The typical brightness, the power consumption and the turn-on voltage of the device were 30 cd/m2, less than 50 mW and 5.0 V respectively. For polymer light-emitting diode, device with structure of ITO/PHF/Al structure was fabricated, where PHF is poly (4, 4’-diphenylene diphenylvinylene). This device has turn-on voltage at 23.0 V. A reduction of turn-on voltage of this device is achieved by using a nanocomposite layer consisting of PHF and SiO2 nanoparticles as the emitting layer. A white OLED combines with colour filters is one of the approaches to obtained full colour flat screen display. White light emitting devices were fabricated with structure of ITO/PHF:rubrene/Al where the white light was optimized through variation of mixing concentrations of PHF and rubrene. The results show that the combination of 0.6 wt% PHF and 0.06 wt% rubrene produced the optimum white light at CIE coordinate of (0.31,0.31). The standard coordinate for white light is (0.33,0.33). The turn-on voltage of this device is 14.0 V and the brightness is 6541 cd/m2. The turn-on of this device was reduced to 8.0 V through an annealing process at 150°C. Keywords : Organic light emitting diodes (OLEDs), small molecule device, polymer light-emitting diode, display

Formation of Monolayer Polystyrene Array Template for Gold Nanomesh Structure

In this study, the preparation of monolayer array template was performed using 0.2 µm polystyrene (PS) nanospheres monodisperse micro particle deposited onto Indium Tin Oxide (ITO) coated glass substrate. The template was used to arrange the gold (Au) in nanomesh structure thus, enhance its homogeneity for having better sensitivity and repeatability in the plasmonic sensor application. PS nanosphere template was prepared by diluting 0.2 µm PS liquid with ethanol in the ratio of 1:3 and stirred with 400 rpm for 1 hours at 40 °C. Next, the PS solution was spin coated on ITO substrate at different speed variation starting from 200 rpm to 800 rpm in 3 minutes at room temperature. The template structure was then inspected with Field Emission-Scanning Electron Microscopy (FESEM). It was found that, the PS nanosphere template with 600 rpm speed shows the most orderly arrangement of PS array. Subsequently, the PS array template was used as a mask to deposit gold (Au) and performed via direct current (DC) sputtering method. Finally, the Au nanomesh structure was obtained using the lift ‒ off process of PS nanosphere template

Reka bentuk sensor pendar cahaya bintik kuantum ZnCdSe untuk mengesan racun perosak

Racun perosak digunakan secara meluas dalam sektor pertanian bagi meningkatkan hasil pengeluaran tanaman. Namun demikian, racun perosak boleh memudaratkan kesihatan manusia, haiwan, ikan dan menyebabkan pencemaran alam sekitar terutamanya pencemaran air. Kertas ini melaporkan kajian pembangunan sistem sensor pendar cahaya untuk mengesan kehadiran racun perosak di dalam air dengan menggunakan filem nipis bintik kuantum. Sistem sensor pendar cahaya mempunyai empat bahagian: sumber cahaya untuk menguja racun perosak, kebuk sensor yang mengandungi sampel racun perosak, serat optik yang memandu cahaya daripada sumber ke kebuk sensor dan sistem analisis. Penduga serat optik dupleks berfungsi menyalurkan sumber cahaya penguja dan pancaran. Pada bahagian hujung serat optik terdapat permukaan kaca pada penduga yang dimendapkan dengan filem nipis bintik kuantum ternari ZnCdSe yang disintesis menggunakan kaedah kimia basah pada suhu 350°C dan masa pertumbuhan hablur ZnCdSe adalah 5 min. Pengesanan racun perosak diukur dengan membandingkan spektrum pendar cahaya (PL) filem nipis ZnCdSe di dalam air dan di dalam larutan racun perosak dengan variasi kepekatan 2.5 hingga 2500 μg/L. Pengesanan dalam uji kaji ini menunjukkan spektrum PL filem nipis ZnCdSe menurun apabila dicelupkan ke dalam larutan racun perosak berbanding dengan puncak spektrum di dalam air. Peratus perbezaan penurunan PL meningkat dengan peningkatan kepekatan racun perosak dan bergantung secara linear kepada kepekatan racun perosak

Photosensitizing Effect of Porphyrin Films as Organic Photodetector

Key words: Organic photosensitizer, natural porphyrin, titanium dioxide anatase, phorocurrent Abstract: A set of organic photodetector devices arranged as indium doped tin oxide (TTO)/porphyrin/TiOialuminum has been fabricated and its performance has been tested in dark and under various illumination of visible light intensity from 20-100 mW/cm2. Four devices were prepared using natural porphyrin by I, 3, 5 and 7 times of spin coating. First, porphyrin film was deposited onto indium doped tin oxide (!TO)-covered glass substrate by spin coating technique. Second, titanium dioxide (Ti02) film was deposited on top of the porphyrin film using similar technique. Porphyrin was isolated from spirulina microalgae and Ti02 nanoparticle was prepared by controlled hydrolysis technique using titanium(IV) etoxide, Ti(OC2Hj)4, and potassium chloride. The films were characterized by UV-vis spectrophotometer to investigate their absorption spectra. The porphyrin film has maximum absorbance at 660 nm, which is in the red region. Then, an aluminum electrode was prepared on top of TjO, film by electron beam evaporation technique. The resulting device shows rectification property in dark and shows photosensitizing effect under illumination. The device prepared by 3 times of spin coating of porphyrin films shows the highest current density, J,c, of 5. 76 rlA/clll2 and open circuit potential, V"c, of 648 mV, respectively

A simple route to vertical array of quasi-1D ZnO nanofilms on FTO surfaces: 1D-crystal growth of nanoseeds under ammonia-assisted hydrolysis process

A simple method for the synthesis of ZnO nanofilms composed of vertical array of quasi-1D ZnO nanostructures (quasi-NRs) on the surface was demonstrated via a 1D crystal growth of the attached nanoseeds under a rapid hydrolysis process of zinc salts in the presence of ammonia at room temperature. In a typical procedure, by simply controlling the concentration of zinc acetate and ammonia in the reaction, a high density of vertically oriented nanorod-like morphology could be successfully obtained in a relatively short growth period (approximately 4 to 5 min) and at a room-temperature process. The average diameter and the length of the nanostructures are approximately 30 and 110 nm, respectively. The as-prepared quasi-NRs products were pure ZnO phase in nature without the presence of any zinc complexes as confirmed by the XRD characterisation. Room-temperature optical absorption spectroscopy exhibits the presence of two separate excitonic characters inferring that the as-prepared ZnO quasi-NRs are high-crystallinity properties in nature. The mechanism of growth for the ZnO quasi-NRs will be proposed. Due to their simplicity, the method should become a potential alternative for a rapid and cost-effective preparation of high-quality ZnO quasi-NRs nanofilms for use in photovoltaic or photocatalytics applications

Customer satisfaction on e-SERVQUAL in Islamic online banking services / Nurhazirah Hashim …[et al.]

The recent development in the ecommerce services has shown a variety of established companies participating in the web business environment including Islamic banks. Business with the most experience and success in using ecommerce are beginning to realize that the indicator of success or failure of the ecommerce environment was included in the online services. Nowadays, the trend of a business is to serve the customer with best quality of services to enhance the consumer satisfaction and compete with the global competitors as online services enabled registered user to make products purchase transaction only through website such as check and manage financial standing, transfer funds, bill payment, prepaid reload and so forth. However, in recent times, Islamic banking users faced problems with the online system such as cannot log in to the system, payment failure and mostly security and privacy hindrance. Therefore, this study aimed to investigate the relationship between electronic service quality (e-SERVQUAL) and customer satisfaction towards Islamic Online Banking Services users. Based on the sample size, only 76 respondents were selected to participate in this study by using a convenience sampling. Further, Pearson correlation and multiple regression were reported to analyze the mentioned relationship. The findings have shown that there is a positive relationship between e-SERVQUAL and customer satisfaction in using Islamic online banking services. Based on the findings, Islamic online banking developer is recommended to improve more on their responsiveness in order to provide quick response to their customer’s requirements. Moreover, they also should be more reliable in providing accurate information in performing the promised services. They must assure that all of their customers can quickly get responds and true feedback regarding their problems to ensure customer satisfy with service provided. Besides, the safety of the website and the protection of customer information also considered a vital action that should be concerned in order to increase the customers’ satisfaction

A study of abortion in Malaysia from the perspective of pebal code / Farah Yasmin Salleh ... [et al.]

This research primary purpose is to examine the current law of abortion in Malaysia from the Penal Code perspective. This research will emphasize on the current position of section 312 of the Penal Code, mostly on how the law operates in regulating the matters in Malaysia and taking into consideration of an exception that gives abortion their legal status. This research will take into account the opinion and insight of people who are professional and directly dedicated to area of study. These people are knowledgeable and fully aware of the laws and the issue of abortion. The findings of this research would principally to propose and recommend to the current law to fill any ambiguity in law of abortion. This research is fully conducted through library research and interviews. From this research the significant result would lead to make available to recommendation and constructive data of abortion mainly from legal perspective. This would give valuable foundation and groundwork for further research on abortion