Field-independent grating formation rate in a photorefractive polymer composite sensitized by CdSe quantum dots

The rate of grating formation in a photorefractive polymer composite sensitized by CdSe quantum dots is found to be independent of applied field, in contrast to similar composites sensitized by other types of nanoparticles. The photorefractive polymer composite under study consists of poly(N-vinylcarbazole) as the nominal charge transporting matrix, an electro-optic dye, and CdSe quantum dots passivated by tri-n-octylphosphine oxide. Both the field-independent grating formation rate and the lower diffraction efficiency compared to other nanoparticle-sensitized composites are attributed to low initial trap density, i.e., a reduced stability of ionized quantum dots within the composite in the dark. (C) 2002 American Institute of Physics.