Papers by Author: Khaulah Sulaiman

Abstract: The studies on the thermoelectric (TE) properties of 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) and a conducting polymer Poly(ethylenedioxythiopene): poly(styrenesulfonate) (PEDOT:PSS)–PH1000 are presented. PTCDA and PEDOT:PSS have been used as a potential n-type material and a p-type material for the TE device, respectively. The Seebeck coefficients, open circuit voltage and the output power have been obtained for the fabricated TE device. The Seebeck effect was observed on this TE device where the output power in the range of 1 nW/cm2 to 5 nW/cm2,was successfully deduced from this TE device. It was found that the association of PEDOT:PSS and PTCDA have been acting well in this TE device. However, a higher TE performance, in the future could be developed, by applying a thermal treatment and introducing a suitable dopant to this n-type material which may increase the mobility of the electrons and the Seebeck coefficient.

Abstract: Organic semiconductor-based solar photovoltaic cells and sensors are scalable, printable, solution processable, bendable and light-weight. Furthermore, organic semiconductors require low energy fabrication process, hence can be fabricated at low cost as light-weight solar cells and sensors, coupled with the ease of processing, as well as compatibility, with flexible substrates. Organic semiconductors have been identified as a fascinating class of novel semiconductors that have the electrical and optical properties of metals and semiconductors. The continuous demand to improve the properties of organic semiconductors raises the quest for a deep understanding of fundamental issues and relevant electronic processes. Organic semiconductor thin film is sandwiched between two metal electrodes of indium tin oxide (ITO) and aluminum to form organic photovoltaic solar cell. Several types of organic semiconductors have been utilized as the photoactive layer in the solution processable organic solar cells. The performance of the fabricated solar cells can be improved by dissolving the material in the right choice of solvent, annealing of organic thin film, slowly forming the thin film and introducing an infra-red absorbance layer. Besides, organic semiconductor-based sensors can be fabricated utilizing either in a sandwidch type or planar type device. Some of these techniques and the experimental results are presented.

Abstract: Two types of polar solvent materials; namely glycerol and ethylene glycol (EG) were used in this study as dopants for PEDOT:PSS. The 2 to 10% of doped PEDOT:PSS were synthesized using sol-gel technique and were spin-coated onto glass substrate. The optical, conductivity and morphological characteristics of the doped PEDOT:PSS thin films were measured via UV-VIS spectrometer, two-point probes technique and AFM measurement, respectively. All films show direct band gap behavior and compared to the pristine thin film, the doped PEDOT:PSS show higher transparency in visible range. Furthermore, the conductivity of glycerol and EG doped PEDOT:PSS thin films were also improved due to the changes in molecule alignment and interchain interaction in the thin films.

Abstract: The molecular organization of the phospholipids Langmuir-Blodgett (LB) films on solid substrates has been studied via Fourier Transform Infra Red (FTIR) spectroscopy. In this study, the formation of well organized ultra thin LB films of phospholipid molecules has been performed by depositing the monolayer onto the solid substrates of silicon wafer. The space filling molecular models of two types of phospholipids have been proposed on the basis of the FTIR spectra.