Darinee Phromyothin

Efficeincy Improvement of Triphenylamine-Based Organic Dyes in DSSCs, An Effects of Linker Moiety

Triphenylamine-base organic dyes were designed and investigated for dye-sensitized solar cells (DSSCs). The dye molecules consist of three parts, an electron-donor connected by the π-conjugated linker (benzene and thiophene) as an electron spacer and an acceptor/anchoring (cyanoacrylic acid). In this study, quantum chemical calculations were used to study the electronic properties, optical properties and density of electron in the linker of dye molecule by using the density functional theory. The results present that thiophene is the most appropriate to use as electron linker between triphenylamine donor and acrylic acceptor due to the wide of absorption band and π-conjugate bond effect on exhibiting red-shifted absorption spectra.

A Study of Fluorescent Chemosensor for Fe(II) Based On Cyanoacrylic Derivatives

A chemosensor based on a cyanoacrylic (DTP-C) consists of dithieno[3,2-b;2’,3’-d]pyrrole(DTP) as a chromophore and a cyanoacrylic moiety as an ionophore which linked by aromatic system. DTP-C demonstrates the response of complex with Fe(II) in dimethylformamide (DMF) solution. The binding mode of Fe(II)/DTP-C complex was characterized using UV-Visible and fluorescence spectroscopy. In addition, the effect of various MES buffer was then studied at 5%, 10%, 15% and 20% v/v in Fe(II)/DTP-C complex which the appropriate ratiomatric of MES buffer is 10%. The enhancement of Fe(II) concentration indicate a decrease emission intensity while the addition of buffer concentrations found to increase in the intensity. Moreover, quantum chemical calculations were used to study the electronic and optical properties of the molecular structure of DTP-C under the density functional theory.

Investigation of Functional Graphene/Cypermethrin Pesticide Molecules by Using Density Functional Theory Calculation

Graphene has received tremendous interest owing to its excellence excellent in electrical conductivity and very high specific surface area. In this work, density functional theory (DFT) is used in order to investigate optical and electrical properties of functionalized graphene which interacted with cypermethrin pesticide molecules. The structures of graphene and pesticide were designed and optimized with M06-2x/6-31G(d,p) method of calculation. Graphene was functionalized by carboxyl, amine and hydroxyl groups to investigate the cypermethrin molecules. The binding energy, band spectra, optical properties and electron distribution of complexes were analyzed. The results reveal that the functionalized graphene with hydroxyl group can highly improve the interaction between graphene and cypermethrin with the lowest binding energy.

Schiff Base modified on CPE electrode and PCB gold electrode for selective determination of silver ion

The schiff base was synthesized by 2,5-thiophenedicarboxaldehyde and 1,2,4-thiadiazole-3,5-diamine with condensation method. There was modified on carbon paste electrode (CPE) and Printed circuit board (PCB) gold electrode for determination silver ion. The schiff base modified electrodes was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The electrochemical study was reported by cyclic voltammetry method and impedance spectroscopy using modified electrode as working electrode, platinum wire and Ag/AgCl as counter electrode and reference electrode, respectively. The modified electrodes have suitable detection for Ag+. The determination of silver ions using the modified electrodes depended linearly on Ag+ concentration in the range 1×10-10 M to 1×10-7 M, with cyclic voltammetry sensitivity were 2.51×108 μAM-1 and 1.88×108 μAM-1 for PCB gold electrode and CPE electrode, respectively, limits of detection were 5.33×10-9 M and 1.99×10-8 M for PCB gold electrode and CPE electrode, respectively. The modified electrodes have high accuracy, inexpensive and can applied to detection Ag+ in real samples.

A Study and Characterization of Photophysical Properties of Fluorene Derivative Thin Film

An emissive layer, fluorene derivative, was performed for organic light-emitting device properties. The preparation of fluorene derivative thin film by spin coating and convective technique was studied the band diagram of thin films which its properties out as the energy gap (Eg). UV-Visible spectrophotometer has been used to investigate the thin film properties. The results indicates spectacular property which occurs the optical properties, fluorescence in thin film and luminescence as a green light in device that it could be applied as emissive layer for organic light-emitting diodes (OLEDs) since the appropriate work function with cathode and anode, aluminum metal and indium tin oxide layer (ITO), respectively.

Fabrication of Zinc Oxide Nanorods for Photoelectrochemical Water Splitting Application

Abstract. Zinc oxide nanorods (ZnO-NRs) as a photoelectrochemical water splitting electrode have been fabricated by the seed-assisted hydrothermal process. Initially, ZnO-seed thin film was deposited on indium doped tin oxide (ITO) via DC magnetron sputtering system. Period to fabricate ZnO-NRs, the precursor concentration of zinc nitrate (Zn(NO3)2) and hexamethylenetetramine (HMTA) were precisely controlled during 10 – 50 mM, meanwhile the ratio was constantly kept at 1:1. The crystallography and surface morphology of the fabricated ZnO-NRs were investigated by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The XRD patterns perform wurtzite ZnO crystal structure of with the prefered orientation in (002) and (101) plane. According to FE-SEM photograph, growth rate, density and diameter of the fabricated ZnO-NRs electrode significantly increase, with the increasing of the precursor concentration. This precursor concentration provides a crucial role on the feature of ZnO-NRs for photoelectrochemical water splitting electrode. Finally, the photoelectrochemical water splitting performance was examined and provided that the precursor concentration became close to 30 mM in 1 M Na2SO4 exhibited the highest photocurrent.

Tantalum oxide bio-photonics thin film grown by Gas-timing innovation technique

Tantalum oxide (TaxOy) as high refractive index material has been grown on p-type silicon and quartz substrates by R.F. magnetron sputtering with our innovative technique called “reactive-gas timing”. The reactive gas timing technique is an on-off time period sequence between argon (Ar) and oxygen (O2) plasma during sputtering process. The technique of gas-timing plays the effect on the properties of TaxOy thin film. The bombarded Ar-plasma was varied at 2, 5 and 8 sec, while the period of reactive O2-plasma was kept at 5 sec in this experiment. The physical and optical properties were investigated by using X-ray diffraction (XRD), Atomic Force Microscope (AMF), UV-Visible spectrometer and Spectroscopic Ellipsometer, respectively. The XRD spectra and AFM photographs show all films are amorphous phase with smooth feature. Meanwhile the transmittance of sputtered thin film decreases with 10% and the absorption edge shifts to lower energy with the increasing of the argon period from 2 sec to 8 sec. The refractive index as showed by ellipsometry slightly increases from 2.08 to 2.17 at wavelength 550 nm with the increasing of argon period from 2 sec to 8 sec. The increasing of the refractive index might dues to tantalum (Ta) rich which consists in thin films. The Ar-plasma period in the deposited film plays an important role on the properties of the TaxOy thin films especially as optical refractive index material.

Effect of Operated Pressure on Anticorrosive Behavior of Ta2O5 Thin Film Grown by D.C. Reactive Magnetron Sputtering System

Tantalum oxide (Ta2O5) thin films, 100 nm thick were deposited by D.C. reactive magnetron sputtering system at different operated pressure on unheated p-type silicon (100) wafer and 304 stainless substrates. Their crystalline structure, film surface morphology and optical properties, as well as anticorrosive behavior, were investigated. The structure and morphology of films were characterized by grazing-incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The optical properties were determined by spectroscopic ellipsometry (SE). The corrosion performances of the films were investigated through potentiostat and immersion tests in 1 M NaCl solutions. The results showed that as-deposited Ta2O5 thin films were amorphous. The refractive index varied from 2.06 to 2.17 (at 550 nm) with increasing operated pressure. The corrosion rate of Ta2O5 thin film improves as the operated pressure decreases. The Ta2O5 thin films deposited at 3 mTorr operated pressure could be exhibited high performance anticorrosive behavior.