Muhamad Saipul Fakir

Modification of Optical Band Gap and Surface Morphology of NiTsPc Thin Films

We demonstrate the effects of solvent treatment on the optical band gap and surface morphology of nickel (ii) phthalocyanine tetrasulfonic acid tetrasodium salt (NiTsPc) thin films. The optical band gap and surface morphology modifications are carried out by immersing the films in chloroform for different immersion times until the optimized time (60 min) is found. A Tauc plot is used to calculate the optical energy gaps, which are found to be about 2.70–2.85 eV and 1.43–1.50 eV, in the B and Q bands respectively. AFM topography shows that more granular structures have been formed upon the optimized immersion time. Photoluminescence (PL) quenching occurs in the solvent-treated NiTsPc film incorporated with a tris(8-hydroxyquinolinato)aluminium (Alq3) layer. This PL quenching indicates that the charge carrier transport is more efficient at the interface between NiTsPc/Alq3 as a result of the solvent treatment.

Organic Semiconductors: Applications in Solar Photovoltaic and Sensor Devices

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.