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.