Study of optical anisotropy in thin films of polithiophene derivate

Abstract

Conducting polymers have interesting optical and electrical properties due to the alternating single and double bonds along the main linear chain. The conducting polymers are used for various applications since sensors to photovoltaic cells. For the fabrication of such devices, the polythiophene are a type of conductive polymer worked in the form of thin films and are transferred to various types of substrates. A highlight technique in the fabrication of polythiophene films is Langumuir-Blodgett technique, which allows the manufacture of organized films and the control of film thickness. An important optical characterization technique to study the molecular organization of thin films is the optical anisotropy, which shows that the increase in anisotropy is related to the increased packaging of polythiophene chains onto the substrate, where an increase in anisotropy can lead to greater absorption of light incident on the substrate and an improvement in the transport of charge carriers. Thus, the aim of this study corresponds to the study of the morphological properties of thin films fabricated from regioregular alkylated derivatives of polythiophene(P3AT) by Langmuir-Blodgett technique. The materials that will be used in this study are the regioregular alkylated derivatives of polythiophene such as poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-octylthiophene) and poly(3-decylthiophene), abbreviated by P3BT, P3HT, P3OT and P3DT, respectively. Furthermore, the materials will be added with stearic acid (amphiphilic molecules). The films will be fabricated in a KSV 5000 Langmuir trough. For the analysis of anisotropy, the polarization measurements will be carried out using a spectrophotometer Cary 100, in a range between 300 and 800 nm, with a polarizing type Glan Thompson Polarizer (SMP-model PTH). From these studies is expected to obtain information related to the structure of organic thin films through measures by UV-Visible absorption and optical anisotropy, to improve the understanding of the organization of layers by Langmuir-Blodgett technique. (AU)