Organic photorefractive crystals

Photorefractivity in an organic material was first reported in 1990 [36] by the ETH Zurich group in an organic single crystal. The same year a group at Eastman Kodak developed a multifunctional polymer that showed photoconductivity and... 

The Photorefractive Effect in Crystals and Amorphous Organic Media... 

Since the discovery of the photorefractive effect in LiNbOj crystals, early investigations dealt exclusively with — incidentally, expensive — inorganic single crystals (e.g., LiNbOj, BaTiOj) and semiconductors (e.g., GaAs). Difficulties in the processing of these materials into the desired (thin film) forms have hampered practical applications. The first observation of photorefractivity in an organic material in 1990 caused attention to spread to photorefractive polymers because they can be easily modified and processed into a variety of thin film configurations as required by the application. ... 

Inorganic organic hybrid polymer dispersed liquid crystalline nanocomposites are reported as suitable candidate for fahricatirHi of photorefractive medium. Winiarz et al. reported one such photorefractive medium which consists of hole transporting polymer composite matrix, electro-opticaUy active nanodroplets of liquid crystal and Cadmium sulphide quantum dots as photosentizers (Winiarz and Prasad 2002). They employed poly(methylmethacrylate) (PMMA) as polymer matrix, N-ethylcarbazole (ECZ) as hole transporting medium and commercial nematic liquid crystal mixture TL 202 for fabrication of the photorefractive medium with Cadmium sulphide as photosentizer. The reported medium exhibits more than 90 % internal diffraction efficiency which is relatively high compared with other PDLC photorefractive medium. 

Winiarz JG, Prasad PN (2002) Photorefractive inorganic-organic polymer-dispersed liquid-crystal nanocomposites photosensitized with cadmium sulfide quantum dots. Opt Lett 27 1330-1332... 

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