Monolithic Photorefractive Molecular Glass with Electron-Transporting Fluorene Unit

Abstract

Multifunctional succinates have been prepared as monolithic molecular photorefractive materials which contain an electron-transporting fluorene moiety and an electrooptically active (EO) chromophore. The synthesized succinates form amorphous glass at room temperature with the aid of a flexible diester spacer and butoxycarbonyl group attached to the fluorene unit. Long-wavelength absorption bands were observed in addition to the peaks from fluorene and the EO chromophore, which are due to the charge transfer interaction between electron-accepting fluorene and electron-donating aniline units. Compounds showed photorefractivity without the addition of a photosensitizer, a polymeric binder or a plasticizer, indicating that they are completely monolithic photorefractive materials. Succinate with a 4-dicyanovinylaniline chromophore showed excellent properties, i.e., 32% diffraction efficiency at 55 V/µm and 125 cm-1 coupling gain at 65 V/µm. The electron-transporting nature of space-charge field buildup was confirmed from the coupling direction.