Pekik Nurwantoro

Velocity Measurement of EHD Flow Produced by Pin-Multi Concentric Ring Electrodes Generator

Study of EHD flow by using generator corona discharge with electrodes configuration of pin to multi concentric rings (MCR) and pin to single ring (SR) have been curried out. We measured the velocity of EHD flow and determined the comparison of velocity of EHD flow produced by pin to single ring electrodes. The pin needle was made by stainless steel with a length of 50 mm and a tip diameter of 0.14 mm. The multi-ring electrodes constracted by three concentric rings with a metal material connected to each other and each ring has a diameter of 24 mm, 16 mm and 8 mm in width and the same ring thickness is 2 mm and 3 mm. Single ring electrode has a diameter, width and thickness respectively 24 mm , 3 mm and 2 mm. EHD was generated by using a DC high voltage of 10 kV. Pin as an active electrode of corona discharge and concentric rings multi/single ring electrodes as ions collector and passive electrodes. The velocity of EHD flow was measured by a hot-wire anemometer. We found that the velocity of EHD flow with multi-ring concentric electrodes larger than a single ring electrode. The measurement of velocity for two cases of electrodes configuration were limited at the certain voltage due to breackdown and arc phenomena. The maximum velocity of the of EHD flow using a pin-multi rings concentric was 0.7 m/s at a voltage of 6 kV.

Structural Evolution and Optical Properties of TiO2 Thin Films Prepared by DC-Reactive Sputtering Technique

Titanium dioxide (TiO2 ) thin films have been deposited on glass substrates under various conditions by using a homemade reactive DC sputtering technique. The TiO2 has unique characteristics and economical alternative material for transparent conductivity oxide thin films compared with other materials. In this study, titanium (Ti) has been used as a target while argon (Ar) and oxygen (O22</subthin films has been measured by using a calibrated I-V meter. On the other hand, the transparency, microstructure and component of TiO2 thin films have been investigated respectively by using UV-VIS spectrophotometer, XRD and SEM (EDX). The thickness of TiO2 films, the grain size and the band gap have been also successfully estimated. As a result, the conductivity of films increased for Dt at 1 hour to 3.5 hours and decreased for Dt at 4 hours. It means that the optimum Dt was at about 3.5 hours. It may be related to the thickness (structures) of the films. In addition, the thickness and grain size increased by increasing Dt, while the band gap decreased when the film structure changed from non-crystalline structure to crystalizing structure.

Commensurate effects in the square superconductor with a regular holes array

Time dependent Ginzburg‐Landau equation was used to investigate the commensurate effect in superconductor having lattice holes arrays. Study was focused on the visualization of the commensurate effects on the superconductor having holes arrays and on the critical cunent density enhancement. It was found that when the superconductor having electric current density exposed on perpendicular magnetic field, the critical current density was enhanced through commensurate effect. The enhancement factors on critical current were influenced by the holes size, number of holes, and lattice holes geometry.

Spreading Dynamics of Corrosion on Material Surface Using Site Percolation Model

Spreading phenomenon is usually characterized by existence of two competing processes. On the spreading of corrosion, competition occurs between the power of solution to corrode with the resistance level of a metal surface against corrosion. In the present study, we simulate a corrosion process using site percolation model to determine the spreading pattern of corrosion. The simulation results showed different spreading patterns and dynamics of corrosion when the value of corrode molecules were varied. The simulation results also indicate the emergence of two regimes that happens, smooth regime and random regime. Smooth regime characterized by the shape of its corrosion face is almost the same as before. While random regime characterized by the appearance of random spreading pattern on the shape of corrosion face.

Dielectric constant extraction of graphene nanostructured on SiC substrates from spectroscopy ellipsometry measurement using Gauss–Newton inversion method

The extraction of the dielectric constant of nanostructured graphene on SiC substrates from spectroscopy ellipsometry measurement using the Gauss-Newton inversion (GNI) method has been done. This study aims to calculate the dielectric constant and refractive index of graphene by extracting the value of ψ and Δ from the spectroscopy ellipsometry measurement using GNI method and comparing them with previous result which was extracted using Drude-Lorentz (DL) model. The results show that GNI method can be used to calculate the dielectric constant and refractive index of nanostructured graphene on SiC substratesmore faster as compared to DL model. Moreover, the imaginary part of the dielectric constant values and coefficient of extinction drastically increases at 4.5 eV similar to that of extracted using known DL fitting. The increase is known due to the process of interband transition and the interaction between the electrons and electron-hole at M-points in the Brillouin zone of graphene.

Theoretical Determination of The Optimum Thickness of Perylene Layer in Bilayer Phthalocyanine/Perylene Photovoltaic Device

We do theoretical study on thickness of the active layers in a heterojunction bilayer thin film photovoltaic device based on copper phthalocyanine (CuPc)/perylene that gives the highest Incident Photon to Current Efficiency (IPCE). The device we study consists Glass (1 mm)/ITO (Indium Tin Oxide, 120 nm)/CuPc (50 nm)/PTCDA (3, 4, 9, 10‐perylenetetracarboxylic dianhydride, x nm)/Ag (40 nm), where x is the thickness of the PTCDA layer that we calculate here. The calculation is based on assumption that the photocurrent generation process is the result of the creation of photogenerated excitons, which difuse before dissociated at the CuPc/PTCDA interface following the diffusion equation, by internal optical electric field that comes from light exposure. We also assume that almost all photocurrent is created in the CuPc/PTCDA interface. Because the order of the thickness of the active layers is the same or smaller than of the wavelength of visible light, we take into account the effect of reflection and interfe...

INFLUENCE OF OPTICAL FILTER EFFECT ON THE INCIDENT PHOTON TO CURRENT EFFICIENCY OF HETEROJUNCTION ORGANIC PHOTOVOLTAIC DEVICES

The origin of incident photon to current efficiency (IPCE) of single heterojunction organic photovoltaic devices consisting of copper phthalocyanine (p‐type) and perylene (n‐type) layers has been investigated by means of optical filter effect phenomenon. The p/n type and n/p structure devices were fabricated by sandwiching p/n and n/p layers between two metal ohmic contacts, respectively. Under illumination of white light, the optical filter effect phenomenon was clearly observed, i.e. the contribution of n layer to the exciton generation was observed at 535 nm for the p/n devices, while for the n/p devices the contribution of p layer was stronger, at 635 nm and 700 nm, than that of the n layer. The symbatic like of IPCE action spectra indicate that the exciton dissociation effectively takes place at the p/n interface.