Observation of the photorefractive effect in a hybrid organic-inorganic nanocomposite

We report the observation of the photorefractive effect in an organic-inorg anic polymer composite photosensitized with nanosized cadmium sulfide parti cles, the surface of which is passivated utilizing p-thiocresol. The semico nductor nanoparticles are dispersed in a poly(M-vinylcarbazole) (PVK) polym er matrix that also acts as the charge-transport species. The ability of th ese particles to behave as the photosensitizer in a PVK matrix has been cha racterized through a de photoconductivity experiment. In addition, for the photorefractive experiments, the second-order optically nonlinear chromopho re 4-nitrophenyl-L-prolinol is also doped into the PVK matrix to elicit ele ctro-optic response. Tricresyl phosphate is used to lower the glass-transit ion temperature of the material, allowing for room temperature in situ poli ng of the sample. In addition to the electric field dependence of the degen erate four-wave mixing diffraction efficiency, the photorefractive nature o f the grating is confirmed via two-wave mixing asymmetric energy transfer. The paper also discusses briefly the methods employed in the syntheses of t he capped CdS nanoparticles used in this study, which include the reverse m icelle approach as well as competitive reaction chemistry. The resulting pa rticles have been characterized using UV-vis absorption and X-ray diffracti on.