Photogeneration, charge transport, and photoconductivity of a novel PVK/CdS-nanocrystal polymer composite

We report on the photoconductive characteristics of an inorganic:organic hy brid composite in which PVK serves as a polymeric charge-transporting matri x and quantum dots composed of surface passivated cadmium sulfide serve as a charge-generating sensitizer. The PVK:CdS nanocomposites prepared are dir ectly compared with a similar composite composed of PVK and C-60, an extens ively studied system due to its promising characteristics. We demonstrate t he possibility of tuning the band-gap of these sensitizing nanocrystals thr ough 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 characte ristics exceeding those observed in the PVK:C-60 system. In this paper resu lts concerning photosensitivity will be presented and the Onsager formalism developed for organic systems will be employed in order to extract the par ameters r(0) and Phi(u) from the photocharge generation efficiency data. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.