Effect of Donor−Acceptor Substitution on the Nonlinear Optical Properties of Oligo(1,4-phenyleneethynylene)s Studied by Third Harmonic Generation Spectroscopy

Abstract

Third-harmonic generation (THG) spectroscopy was performed for oligo(1,4-phenyleneethynylene)s (OPEs) with terminal donor−acceptor (DA) substitution and compared to the results of merely donor substituted OPEs and regular OPE chains with 2,5-dipropoxy benzene rings. Both, extension of the conjugation and push−pull effect enhance the molecular hyperpolarizability γ, even for the DAOPEs, which exhibit a hypsochromic shift of the long-wavelength absorption for increasing length L of the conjugated chain.