Effect of nanoparticle composition on the performance of photorefractive polymers

A photorefractive polymer composite has been sensitized by three different types of CdSe/ZnS core/shell nanoparticles, which are of similar sizes and nominally of the same composition but different in detail. The composites comprise the nanoparticles, poly(N-vinylcarbazole) and the electro-optic chromophore 1-(2-ethylhexyloxy)-2,5-dimethyl-4-(4nitrophenylazo) benzene. The nanoparticles are characterized by elemental analysis, absorption and photoluminescence spectroscopy, transmission electron microscopy and powder X-ray diffraction. The electro-optic response of the composites is measured by transmission ellipsometry, photorefractivity is confirmed by two-beam coupling, and photorefractive performance is determined by degenerate four wave mixing. The results indicate that, even for ostensibly similar nanoparticles, small differences in composition have a significant effect on the photorefractive performance.