The paper reports the fabrication of fluorine-doped zinc oxide/p- silicon (ZnO/p-Si) heterojunction solar cells and the effects of fluorine content on efficiency of these solar cells. Fluorine-doped zinc oxide nanoparticles (FZO) were synthesized using sol-gel method and heterojunctions of n-FZO/p-Si solar cells were fabricated by the spray pyrolysis technique. FZO thin films were also deposited on the glass substrate under the same conditions for the investigation of their optical properties. The structural characterizations of FZO films were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optical characterization of these thin films was studied by UV-Vis spectroscopy and transmittance values of over 84% were obtained at the visible region. The current-voltage characteristic of the n-FZO/p-Si heterojunction solar cells was measured at room temperature in the dark and under illumination (90 mW/cm(2)). Series resistance (R-s) values obtained from solar cells were found between 5.52 and 10.12 ohm. The conversion efficiency of the fabricated solar cell of between 3.82 and 6.74% was obtained.