Enhancement of the Photorefractive Response Time in a Polymeric Composite Photosensitized with CdTe Nanoparticles

Abstract

Because of their enhanced spectral response, photorefractive polymeric composites photosensitized with semiconductor nanocrystals are emerging as an important class of materials. Despite their promising characteristics, however, several deficiencies persist. Relatively low diffraction efficiencies and slow response times have prevented these materials from reaching their full potential. In this work we demonstrate the ability to enhance a composite's response time by nearly 1 order of magnitude without significantly ceding diffraction efficiency through judicious selection of semiconductor material. By replacing the commonly employed cadmium selenide nanocrystals with those of cadmium telluride, the response time was enhanced from 1.05 s to 171 ms. Moreover, through careful control of the photorefractive device's absorption characteristics, this augmentation in response time is accompanied by a relatively small decrease in internal diffraction efficiency from 24% to 20%.