Mohd Nizam Yusli

This research work investigates the influence of the solvent used upon the formation of polymeric photoactive layer. This photoactive layer consists of a blend of poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to produce P3HT:PCBM (at 1:1 ratio) blend thin films, in which the material solutions are deposited onto clean substrates via spin-coating technique. Three types of solvents were used namely: 100% dichlorobenzene (DCB), 100% chloroform (CH) and 50%:50% mixture of DCB and chloroform. The results reveal that the mixture of solvent produces a better solubility of the polymeric materials compared to that of the pure single solvent.

In this article we report the nanostructures formation in the thin films of several organic semiconductors. The thin films have been deposited onto glass substrates by a solution processable of spin-coating technique. The nanostructures are obtained by applying a simple surface solvent treatment process either by soaking or solvent vapor treatment. The influence of solvent treatment on the surface morphological properties has been investigated via a surface profilometer, absorption spectroscopy, Xray Diffraction Spectroscopy and Atomic Force Microscopy (AFM). It reveals that the spin-coated TsCuPc thin films have nanostructures as evident from the surface profile image, which then confirmed by AFM image. Besides, the polymer chains have been re-organized after solvent treatment and the crystallinity is increased. Such crystalline increment provides a better pathway for charge carrier transport. The photovoltaic performance has improved to some extent for the device containing nano-structured film. We infer this enhancement is due to a larger interface area for exciton dissociation to generate free charge carriers of electrons and holes within the nanostructured film.

Bulk heterojunction polymer solar cell is widely investigated throughout the decade. This is due to its potential as an alternative to inorganic solar cell such as silicon-base solar cell. Compared to inorganic solar cell, polymer solar cell is low in cost, much easier to fabricate and shows higher mechanical flexibility. Two types of conjugated polymers has been used in this study; [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly(3-hexylthiophene) (P3HT). Many methods have been used to improve the efficiency of the solar cell. Thermal treatment on the organic layers has been utilized to increase the solar cell efficiency by improving the morphology and structure of the sample. It has been reported that by using different preparation methods, such as „slow grown‟ and „fast grown‟, the efficiency is enhanced. The morphology of the sample also varies when different solvent are used. In this study, we report the effect of thermal treatment on the optical, structural and morphological properties of the P3HT:PCBM blend thin films. The absorption, Raman, photoluminescence as well as x-ray diffraction spectra of the films will be discussed. The influence of thermal treatment on the performance of the P3HT:PCBM-based solar cells also investigated. The effect of solvent used also been discuss in this study. The polymer materials solutions were prepared using two types of solvents; 100% dichlorobenzene (DCB), 100% chloroform and 50%:50% mixture of DCB and chloroform. Then, the morphological characterizations of P3HT:PCBM bulk thin films were carried out by UV-Visible absorption spectroscopy, X-ray diffraction (XRD) spectroscopy, Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM). Furthermore, the P3HT:PCBM photoactive layer was sandwiched between two different electrodes of iv aluminum (Al) and indium tin oxide (ITO) to form the polymeric-based solar cells, namely ITO/P3HT:PCBM/Al devices. In this study it has been found that the thermal treatment process has a significant effect on the sample. Using different fabrication process also play a major role in improving the structure of the sample. Other than that, results of this study also indicate that solar cells employing the P3HT:PCBM bulk thin films prepared from the solvent mixture exhibit the enhanced fill factor and short-circuit current than that of other cells.

This work investigates the influence of the solvent used on the morphology of polymer photoactive layer for solar cells. The photoactive layer consists a mixture of poly(3‐hexylthiophene) (P3HT) and [6, 6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), to produce P3HT:PCBM (1:1 ratio) blend thin films, deposited by spin‐coating technique of the materials solution. Two types of the solvents used namely; 100% dichlorobenzene (DCB) and 50%:50% cosolvent of DCB and chloroform. The morphological characterizations of P3HT:PCBM blend thin films have been carried out by UV‐Visible absorption spectroscopy, X‐ray diffraction (XRD) spectroscopy, and Atomic Force Microscopy (AFM). The results reveal that the mixtures of solvent give a better solubility than the pure single solvent. And thus, the choice of solvent used during the fabrication process can significantly affect the optical and morphological properties of the films.