Gold nanoparticles (AuNPs) of various sizes were formed by different chemical methods. The particle sizes as being (5 nm, 7 nm, and 17 nm) and sphericity, were assessed in images from a transmission electron microscope (TEM(). The effects of the particle sizes on the plasmon bands were explained by ultraviolet-visible spectra measurements. Copper phthalocyanine (CuPh) films embedding of AuNPs nanoparticles on (ITO/Glass) substrates were dconducted, using spin coater under vacuum. The morphology of the films was discussed from scanning electron microscope (SEM) images. The results focused on current–voltage (I–V) measurements under dark, and illumination of the films embedded with different AuNPs sizes awere discussed, and the effect of the sizes on thin films as photovoltaics cells (PEC) were clarified. The PEC was increased withby increasing the particle sizes at (5 nm, 7 nm, and 17 nm) to (0.237%, 0.266% and 0.280%) receptivity. This means that the large particle sizes for AuNPs increase the efficiency of the solar cell due to the increasing of the scattering and decreasing in the reflection at the surface of the thin film.