Enhanced optical nonlinearity and improved transparency of inorganic-organic hybrid materials containing benzimidazole chromophores.

A series of novel inorganic-organic hybrid materials with benzimidazole chromophores covalently bonded into the inorganic silica network as pendants has been designed and synthesized via the wet chemistry routes. The measurement results of solvatochromic method and UV-vis spectra indicate that these benzimidazole chromophores exhibit higher microscopic optical nonlinearity compared with their analogues with benzene ring and without undesirable red-shift of the absorption band. After corona poling, the macroscopic nonlinear optical activity and poling alignment stability of the hybrid films were investigated by in situ second harmonic generation measurement. These hybrid films exhibit enhanced nonlinear optical coefficient from 25 to 54 pm/V with chromophore concentration varied, improved optical transparency (lambda(max) < 470 nm), as well as excellent polar orientation stability at 160 degrees C.