Effects of substituents on the third-order nonlinear optical properties of poly(3-alkoxythiophene) derivatives

Poly(3-alkoxythiophenes) (P3AOTs) have been synthesized with octoxyl, dodecaoxyl and 4-nitro-benzyloxyl as sidechains, respectively. The novel poly(3-octoxycthiophen)-co-poly(3-(4-nitro-benzyloxy)-thiophene) (P3OOT-co-P3NBOT) has also been prepared. The absorption spectra of samples indicate that the side groups affect the bandgap of P3AOTs. The nonlinear optical (NLO) properties of P3AOTs were investigated using Z-scan method. The third-order NLO susceptibility (χ(3)) of the polymers shows a strong dependence on the length of the alkoxyl sidechains and polarity of polymers, which affect the intra- and intermolecular charge transfer. These polymers have potential application in optical limiting device.