photorefractive (PR) application because of a fast hole mobility. In most of the previous studies, phenyl-C61-butyric acid methyl ester (PCBM) was used as a sensitizer. In this study, a high-performance charge generator perylene bisimide (PBI) is synthesized and added into the composite. PBI derivatives owning a large core of π-conjugated rings provide a high electron affinity and high charge carrier mobility. These features are promising to improve PR properties. To the best of our knowledge, it is the first time for using a combine of PCBM and PBI to improve the PR performance of PDAA-based composites. 2-(4-(azepan-1-yl)benzylidene)malononitrile (7-DCST) is used as a nonlinear optical chromophore. (4-diphenylamino)phenyl)methanol (TPAOH) is used as a plasticizer. Consequently, a diffraction efficiency of 76 % and a response time of 8 ms were obtained with 532 nm green laser under the electric field of 55 V μm-1. As a conclusion, the introduction of PBI is a promising approach for the photorefractive composite owning the video rate response.
Two kinds of triphenylamine (TPA)-based acrylate polymer are applied to photorefractive (PR) composite. Poly(4-
(diphenylamino)benzyl acrylate) (PDAA) have TPA moiety attached to acrylate main chain. Poly(4-((4-
methoxyphenyl)(phenyl)amino)benzyl acrylate) (PMPAA) has a similar structure with a side chain of TPA derivative
modified with a methoxy group at para position. PMPAA shows even more readily ionized than PDAA. TPA plasticizer
is used instead of the conventional N-ethylcarbazole plasticizer to improve the photoconductivity. A series of composite
based on two kinds of acrylate polymer have been prepared and investigated by degenerate four-wave mixing. With the
polymer concentration of 55 and 50 wt%, the composite using modified-TPA-polymer of PMPAA shows significant
improvement in diffraction efficiency and response time. When polymer concentration is reduced to 45 wt%, the PDAA
composite shows a large PR enhancement. With 532 nm laser, diffraction efficiency reaches 70% and 40% for PDAA
and PMPAA composites, respectively.
A new class of photorefractive (PR) composite based on a fully functionalized polymer with high phase-stability is
reported. The polymer containing nonlinear optical (NLO) chromophore and charge-transporting carbazole moieties is
synthesized by a polymer analogous reaction. The polymer is doped with plasticizer, NLO dye and sensitizer to fabricate the PR composite. The NLO dye is the same as the NLO chromophore moiety in the polymer side chain. PR
performance of the composite is evaluated by degenerated four wave mixing and two-beam coupling measurements.
Diffraction efficiency of 30% at relatively low applied electric field of 45 Vμm-1 is achieved. Despite a high
concentration of NLO dye, the composites show good stability for a long period without phase separation.