Boosted electro-optic performance in second-order nonlinear optical chromophores featuring thiophen-2-amine-derived donor groups

Abstract

Two innovative second-order nonlinear optical chromophores, designated as B–C, have been synthesized, featuring thiophene-derived donors and a tricyanovinyldihydrofuran bridge as acceptors. These chromophores have undergone comprehensive characterization. Notably, the donor components of chromophores B–C were (methyl(phenyl)amino)thiophene and (4-methoxyphenylamino)thiophene, respectively, in contrast to the diethylamino phenyl unit present in chromophore A. Density functional theory calculations suggested that the first hyperpolarizability of chromophore C, with a (methoxyphenyl amino) thiophene donor, was approximately 60 % higher than that of chromophores A and B. This indicates that merely substituting the benzene ring with thiophene does not significantly enhance the electron-donating ability of the donor. Polymeric thin films doped with 25 wt% of chromophores A-C exhibited r33 values of 39 p.m./V, 46 p.m./V, and 76 p.m./V, respectively. The electro-optic coefficients of chromophores B and C were 18 % and 95 % higher than that of chromophore A, respectively. These findings confirm that thiophene-derived donors, particularly those with multiple heteroatoms, can effectively enhance the electro-optical coefficient of chromophores.