The influence of ZnS quantum dots (QDs) on the photo-physical and electrical properties of poly(3-hexylthiophene) (P3HT) conjugated polymer, has been investigated. Composite material has been prepared by blending P3HT with low concentration of chemically synthesized ZnS nanocrystals. Absorption spectra of conjugated polymer exhibit a small blue shift of about 3 nm, with the incorporation of ZnS nanocrystals. We observed the charge transfer between conjugated polymer molecules and ZnS nanoparticles which is discussed with the energy levels of the materials. Current density-voltage measurement of the hybrid device showed a significant improvement in V-oc in comparison to P3HT only device. (C) 2010 Elsevier B.V. All rights reserved.