Third-Order Nonlinear Optical Properties of Thiophene Oligomers and Derivatives

Abstract

A series of α, α'-thiophene oligomers and their α, α'-substituted derivatives such as formyl, bromine, and cyano have been prepared in order to discuss the effects of number of thiophene rings and introduction of functional groups on third-order nonlinear optical properties. Optical absorption spectra and optical third harmonic generation (THG) have been studied in vacuum-evaporated thin films or solid solution. The values of λmax, linear polarizabilities and χ⁽³⁾(-3ωω,ω,ω) obtained from THG measurement for thiophene oligomers increase with increasing number of thiophene rings. The introduction of electroactive groups and increasing the molecular planarity enhanced the linear polarizabilities and third-order nonlinear optical susceptibilities.