Photogeneration, Charge Transport, and Photoconductivity of a Novel PVK/CdS-nanocrystal Polymer Composite

We report on the photoconductive characteristics of an inorganic:organic hybrid composite in which PVK serves as a polymeric charge-transporting matrix and quantum dots composed of surface passivated cadmium sulfide serve as a charge-generating sensitizer. The PVK:CdS nanocomposites prepared are directly compared with a similar composite composed of PVK and C60, an extensively studied system due to its promising characteristics. We demonstrate the possibility of tuning the band-gap of these sensitizing nanocrystals through careful discretion in the method of synthesis such that their spectral response can be adjusted to suit a particular wave-length of operation. In this way materials can be fabricated which posses photoconductive characteristics exceeding those observed in the PVK:C60 system. In this paper results concerning photosensitivity will be presented and the Onsager formalism developed for organic systems will be employed in order to extract the parameters r0 and Φ0 from the photocharge generation efficiency data