Nonlinear Optical Property and Morphology of Poly (3-hexylthiophene) Thin Film Fabricated on the Quartz Glass Substrate Treated with Octadecyltrichlorosilane

Abstract

  Polythiophene derivatives in π-conjugated polymers have been attracting the attention of researchers as derivatives retaining extensively potential applications in optoelectronics such as optical switches, optical logic circuits, optical integrated circuit (IC) and so forth. As π-conjugated polymers have high non-localized π electron density, the thin film prepared by π-conjugated polymers has the possibility of a large third order nonlinear optical susceptibility occurring from the thin film. In this study, the π-conjugated polymer used is regioregular poly (3-hexylthiophene-2, 5-diyl) {P3HT}. The substrate preparing P3HT thin film is quartz glass treated by octadecyltrichlorosilane (ODTS) or hexamethyldisilazane (HMDS). P3HT thin films are prepared by a drop-casting on it formed on the surface of quartz glass with self-assembling monolayer (SAM) [ODTS or HMDS]. The molecular orientation or alignment of P3HT thin films with and without SAM is performed using an X-ray Diffraction (XRD) spectrometer and UV/Vis spectrophotometer. Based on these results, the nonlinear optical characteristics of P3HT thin films with and without SAM are performed and investigated with the third harmonic intensity measured by the Maker fringe method.