Quadratic nonlinear optical response of composite polymer materials based on push–pull quinoxaline chromophores with various groups in the aniline donor moiety

Abstract

Composite polymer materials doped with original push–pull chromophores with the quinoxaline core in the conjugated bridge have been developed. Chromophores with various substituents in the aniline donor moiety and tricyanofuran acceptor are characterized by high thermal stability and predicted values of first hyperpolarizability (up to 1000 × 10⁻³⁰ esu). Nonlinear optical (NLO) coefficient d₃₃ of corona-poled polymer films achieved 75 pm V⁻¹ for materials doped with chromophore with N,N-dibutylamino-3-ethylbenzene donor at 25 wt% content, while doping with a similar chromophore with an additional bulky cyclohexylphenyl group in the acceptor leads to maximum d₃₃ value 97 pm V⁻¹ for 40 wt% chromophore content and 65 pm V⁻¹ for neat chromophore material. The temporal and thermal stabilities of the NLO response at room temperature and heating to 50 °C during 100 hours is shown to be high: for some polymer materials the value of d₃₃ remained almost constant for 24 months at room temperature and at least 94% of the response preserved after heating.