Non-classical donor–acceptor chromophores for second order nonlinear optics

Optoelectronic components require materials with large second-order nonlinearities. Recently, various types of non-classical chromophores have been developed, in the hope that they have improved physical properties for materials formation. The main research directions and latest developments reviewed here include multi-dipolar chromophoric assemblies, multiple donor and acceptor chromophores, non-rod-shaped dipolar chromophores, and non-conjugated donor-acceptor chromophores, in which the charge transfer process is through space instead of the π-conjugated bridge.