Second-order polarizability of donor-acceptor substituted oligothiophenes : substituent variation and conjugation length dependence

Abstract

Second-order polarizabilities and excited state dipole moments of a number of donor-acceptor substituted α-oligothiophenes have been investigated by use of electric field induced second harmonic generation (EFISH), solvatochromism and electrooptical absorption measurements (EOAM). The experimental results reveal that oligothiophenes are very effective conjugation units offering substantial enhancement of the second-order polarizability with increasing chain length.