Second‐order nonlinear polarizability of “Push‐Pull” chromophores. A decade of progress in donor‐π‐acceptor materials

Abstract

Fine tuning and switching of nonlinear optical response of ferrocene chromophores has been an area of considerable significance as evidenced by a large number of reports in the current literature. In this personal account, we present linear/nonlinear behavior and structure‐activity relationships of several classes of donor‐π‐acceptor designs using organometallic and organic materials, developed by our research group during the last decade. The results especially the electronic absorption spectral and the hyper‐Rayleigh scattering have been supported by theoretical calculations. Exploiting the redox behavior of ferrocene donor, we have demonstrated switching of quadratic nonlinear optical responses with reversible redox chemistry, which is a useful attribute of nonlinear optical materials. Based on the ease in synthesis, structure diversification and structure‐based large and switchable second‐order optical nonlinearity, these materials are potential candidates for electro‐optic applications.