Synthesis and characterization of novel organic photorefractive materials

Nonlinear optical (NLO) chromophores are essential components in photorefractive materials. Several stilbene derivatives, functionalized with an electron-donating substituent in the 4-position and electron-withdrawing substitutent in the 4′-position, are known to display second-order NLO properties. Commonly used electron-donating groups include ether and amino, while electron-withdrawing groups include nitrile, nitro, and sulfone. Many of the NLO chomophores have absorptions that extend well into the visible wavelength range, potentially interfering with charge generation or sensitization. Additionally, crystallization of NLO chromophores in doped polymer systems often occurs and is undesirable. We wish to report the synthesis and characterization of a new class of electron donor-acceptor substituted low molar mass and polymeric stilbenes. The phosphonate ester functionality is employed as the electron-withdrawing moiety, affording excellent solubility. These materials are single component, i.e., the charge transport functionality is covalently incorporated into the NLO chromophore.