Photorefractive performance of a CdSe/ZnS core/shell nanoparticle-sensitized polymer

We report the photorefractive performance of a polymer composite sensitized by CdSe/ZnS core/shell nanoparticles, and also comprising poly(N-vinylcarbazole) and an electro-optic chromophore. The nanoparticles are characterized by absorption and photoluminescence spectroscopy, elemental analysis, transmission electron microscopy, and powder x-ray diffraction. The electro-optic response of the composite is measured independently of the photorefractive effect by transmission ellipsometry. An asymmetric two-beam coupling gain of 30.6 +/- 0.4 cm(-1) is obtained, confirming photorefractivity. Degenerate four-wave mixing is used to assess photorefractive performance and, at a poling field of 70 V mu m(-1), yields a diffraction efficiency of 4.21%+/- 0.03%, a holographic contrast of 3.05x10(-4)+/- 1x10(-6), a space-charge rise time of 25 +/- 2 s, and a sensitivity of 4.7x10(-5)+/- 4x10(-6) cm(3) J(-1). These results constitute a significant improvement on the performance of previous nanoparticle-sensitized photorefractive polymer composites. (c) 2005 American Institute of Physics.