U. M. Noor

Particles Size and Conductivity Study of P-Type Copper (I) Iodide (CuI) Thin Film for Solid State Dye-Sensitized Solar Cells

Copper Iodide based dye-sensitized solar cells (DSSC) has been reported either deliver small photocurrents or highly unstable. In this research, by added in a small amount of Tetra-methyl-ethylene-diamine (TMED) into CuI sol-gel (CuI in acetonitrile), performance of electrical properties and optical properties of CuI based DSSC have been studied. Particles size and conductivity of CuI solution were measured when addition of TMED to the sol at 0.05M concentrations. Spin-coating technique has been explored to prepare nano-crystalline CuI films at room temperature. The film was examined for their surface morphology, optical and electrical properties by field emission scanning electron microscope (FESEM), ultraviolet visible spectroscopy (UV-Vis), Photoluminescence (PL) and current-voltage (I-V) measurement respectively. The results were then compared with CuI sol-gel which prepared by dissolving CuI powder with acetonitrile only. It showed some improvement to the CuI-based DSSC by incorporation of a small quantity of TMED in the solution of precursor.

Optical Properties and Surface Morphology of PMMA: TiO2 Nanocomposite Thin Films

Sol-gel spin coated PMMA:TiO2 nanocomposite thin films on glass substrates were studied by comparing two types of the sol-gel solutions. Two types of PMMA:TiO2 nanocomposite sol-gel solutions were prepared; one using Degusa (P25), and the other one is using self-prepared TiO2 powder. The self-prepared nanosized TiO2 powder is obtained by drying the TiO2 sol-gel using solvothermal method followed by grinding the TiO2 crystal using ball miller. Triton-X was used as surfactant to stabilize the composite. Besides comparing the nanocomposite solution, we also studied the effect of the thin films thickness on the optical properties and their surface morphology. The optical properties and surface morphology were measured with UV-VIS spectrometer and atomic force microscopy (AFM). The result showed that nanocomposite PMMA with self-prepared TiO2 give high optical transparency than that of with Degusa (P25). The results also indicate that as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO2 particles occurred on top of the thin film and the surface roughness increased when the thickness is increased. AFM results show that nanocomposited PMMA with P25 has high agglomeration particles compared to the other one.

Characterization of Copper (I) Iodide (CuI) Thin Film using TMED for Dye-Sensitized Solar Cells

Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without employing p-type as hole conductor. The p-type as hole conductor was first introduced in 1995 and CuI is preferred among others p-type semiconductors. However, in 2003 utilizing of CuI based DSSC was found unstable by the excessive iodine strongly decreased the photocurrent of the cell. Later then, the stability of CuI based DSSCs was reported can be improved by added small amount of triethylamine hydrothiocyanate (THT) in the CuI coating solution. Following to that, in this work new chemical is introduce as an option to present situation which can give equally or better effective for fabrication of solid-state DSSCs. The chemical is called tetramethylethylenediamine (TMED), is employed to CuI in sol-gel process and their characterizations have been studied. The CuI coating solution was prepared by dissolved CuI powder with acetonitrile and added in 0.5mL TMED. Using spin coating technique the sol then deposited onto glass and silicon substrate at room temperature. The film were analyzed by their particles conductivity using pH meter, surface morphology using Field Emission Scanning Electron Microscope (FE-SEM) and optical properties using ultraviolet visible spectroscopy (UV-Vis) and photoluminescence (PL) measurement. The results of this sol-gel were compared with other CuI sol-gel which prepared by dissolved CuI powder with acetonitrile only. The optical transmittance within ultra-violet range exhibited that thin film is transparent and it optical band gap have been studied. Further clarification and measurements need to be done in order to prove that the proposed chemical can be used as an option.

Electrical Properties of Amorphous Carbon Thin Films Prepared from Natural Precursor of Camphor

Amorphous carbon thin films have been deposited on silicon substrates at different deposition temperatures ranging from 650–800° C. In this work, a natural product, camphor (C10H16O) is used as a carbon precursor. Use of camphor as a precursor for depositing carbon thin film could be more favorable than any other precursors because its single molecule contains both forms of carbon, one sp2 and 9 sp3 carbon atoms. In other words, camphor had both trihedral (sp2) and tetrahedral (sp3) hybridized bonds while diamond and graphite have completely 100% of sp3 and sp2 bonded in their lattice respectively. The electrical properties have been studied using IV measurement. These a‐C films are also characterized using UV‐Vis Spectrophotometer. It was found that increasing deposition temperature had the most influence on the a‐C thin films properties.

Performance evaluation of optical fiber sensor using different oxygen sensitive nano-materials

Three different oxygen sensitive nano-materials namely Pt (II) meso-tetra(pentafluorophenyl) porphine (PtTFPP), Tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) and Pd (II) meso-tetra (pentafluorophenyl) porphine (PdTFPP) has been coated on one end tip of an optical fiber to form optical fiber dissolved oxygen sensor. The performance in terms of fluorescence intensity when exposed to oxygen at various (gaseous) concentrations between the three optical fiber sensors has been performed. Optical fiber sensor probe coated with PdTFPP exhibits the highest sensitivity while Ru (II) complex coated optical fiber sensor demonstrates the highest linearity of all three nano-materials.

Electrical properties and Raman characterization of a-C thin films deposited by thermal CVD

Amorphous carbon (a-C) thin films deposited with thermal CVD, have been characterized by a standard two-probe method using Advantest R6243 DC Voltage Current Source/Monitor and SemiPro Curve Software and Raman scattering experiment at an excitation wavelength of 514.5 nm provided by HORIBA Jobin Yvon (HR800) Raman. The films were prepared at various deposition temperatures ranging from 650–900°C. The conductivity of a-C thin films increased proportionally with the deposition temperature and the film deposited at 750°C shows large photoconductivity. ID/IG ratio of Raman spectra increased relatively with the deposition temperature as an indication of the disorderliness of a-C thin films. This is supported by the optical properties measurement whereby the optical band gap decreased from 0.65 to ∼0.0eV due to the increase of sp2 bonded carbon configuration.

Effect of catalyst on the fluorescence quenching of [Tris (4, 7-diphenyl-1, 10-phenanthroline) ruthenium (II) dichloride] for dissolved oxygen detection

We present the effect of the catalyst for sol-solution preparation of tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride on the fluorescence quenching behavior. Two types of [Ru(dpp)3]2+ sol-solution were prepared with two types of catalyst namely acid hydrochloric (HCl) and ammonium hydroxide (NH4OH) and each of them was mixed with the dye-solution to form [Ru(dpp)3]2+ sol-gel solution. A polymer optical fiber tip was then coated by each of the solutions respectively by immersion method. A LED source at 460 nm was used as the excitation source and fluorescence emissions intensity was measured using a UV/VIS spectrometer. The results showed that the fiber optic coated with the solution using NH4OH gave higher fluorescence intensity.

Comparison on the Electrical, Structural and Optical Properties of CuI Thin Films Deposited by Spin Coating and by Atomization Method

In this study, a novel approach of using two different methods was investigated to prepare the CuI thin films. The CuI thin films in this research were prepared by spin coating method and by mister atomizer. Both methods used CuI powder as a precursor and acetonitrile as a solvent. The thickness of CuI films in this research range from nm – um thickness depending on the deposition technique. The 2 point probe I-V measurement was used to measure the electrical properties. The resistivity of about 106 Ω cm-101 Ω cm was observed with CuI thin films using spin coating technique. Then, the surface morphology shows all the films exhibit a microsturucture CuI particles in a case of mister atomizer method. For optical measurement, the ultraviolet-visible- near infrared (UV-VIS-NIR) measurement (Perkin Elmer Lambda 750) was used. The optical band gap of about ±3.1 eV and ±2.9 eV were observed in those CuI films. These properties of different technique are applicable for application in electronic devices such as in solar cells.

Photoconductivity of nanocomposited MEH-PPV: CNTs thin film for organic solar cells application

Our work focused on nanocomposite MEH-PPV: CNTs prepared by spin coating technique. The MEH-PPV which is in powder form (commercially available) was weighted and then dissolved in Toluene and stirred for 48 hours. Then, a small amount of CNTs were added to the MEH-PPV solution. It is sonicated for 1 hour to ensure that CNTs is well dispersed in the MEH-PPV solution. The addition of CNTs in the MEH-PPV solution yields a nanocomposite MEH-PPV:CNTs solution. The electrical properties of the thin films were studied to identify whether the nanocomposite thin films have ohmic capability or vice versa. Optical properties of the thin films were characterized using UV-VIS-NIR spectrophotometer. From the current-voltage characteristics it can be seen that there is no photo response when light is illuminated to the sample of MEH-PPV blend CNTs. The highest conductivity is at 2 wt% concentration of CNT with 100k Sm−1. It also gives the highest value of absorption spectra which is 0.25 for nanocomposite MEH-PPV: CNTs thin film.

Effects of cobalt doping concentration on the structural, electrical, and optical properties of titanium dioxide thin films

Cobalt-doped titanium dioxide thin films have been successfully deposited using sol-gel spin coating technique. The doping process has been done by mixing cobalt source into TiO2 sol-gel. The doping concentration has been varied and its effects to the structural, electrical, and optical properties of the thin films have been studied. Reduction in electrical resistivity is observed with the increase of cobalt doping concentration. Higher cobalt doping concentration sample also shows a shift of absorption edge to longer wavelength which is a desired characteristic for application in optoelectronic devices.