High diffraction efficiency at low electric field in photorefractive polymers doped with arylimine chromophores

We report on the high photorefractive performance of organic polymers doped with arylimine chromophore (diethylaminosalicylaldiminato)nitrobenzene (H1) and its derivative (diethylaminophenylaldiminato)nitrophenol (H2). Polymer blends of H1 and H2 with PVK : ECZ : C60 at 25 : 49 : 25 : 1 wt% and H2 : PVK : ECZ : PC61BM at the same concentration were fabricated. The electric field (E) steady-state diffraction efficiency dependence and the optical gain were measured through holographic experiments at room temperature. For polymers based on chromophore H2, overmodulation of the diffraction efficiency was measured at just E = 32 V μm-1 obtaining 75%, and for polymers based on H1, diffraction of 87% (overmodulation) at E = 48 V μm-1 was observed. Holographic recording imaging was demonstrated at an electric field of just 10-14 V μm-1.