Khakpoor et. al.: Optical Properties Improvement TiO 2 Thin Films with Adding the Au, Ag or Cu Nanoparticles 8 1. Introduction Semiconductor has a wide range of phenomena respect to conductor and insulator properties, nowadays is interested in different applications in particular physics and electronics technology. .Interesting characteristics and fascinating applications of 2D structures cause especial attention to thin film layers. Titanium dioxide is a white powder with three different phases of anatase, rutile and brookite .TiO 2 band gap is about 3.2 eV (for anatase phase) and is about 3.0 eV (for rutile phase) and so it can absorb light in the ultraviolet range. Also, TiO 2 is a n-type semiconductor and so it has some interesting characteristics like strong oxidizing power, photoinduced hydrophilicity, non- toxicity and long-term photostability. Titanium dioxide (TiO2) remains one of the most promising materials because of its high efficiency, low cost, chemical inertness, ecofriendly nature and Photostability (Fujishima and Hlonda 1927) In optic applications, thin film layers with thickness less than light wavelength (100nm) are used for manufacturing of reflector and transmissive devices [1]. However, the widespread use of TiO2 is hindered by its low utilization of solar energy and self-cleaning properties in the visible region (about 3.5 %) because of the wide band gap TiO2. Therefore, many efforts were concentrated on narrowing the optical band gap of Titania. In order to improve thin layer properties, they are doped with different metal nanoparticles (Fe, Pb, Au, Ag, Sn etc.) and these doped thin layers are investigated with a view to electrical, photocatalytic, hydrophilicity, optical properties, [2-5]. Doping with metal or non- Available online at www.impj.ir International Materials Physics Journal vol. 1 No.2 2013 8-13 Optical Properties Improvement TiO 2 Thin Films with Adding the Au, Ag or Cu Nanoparticles A. A. Khakpoor 1 , R. Borjian 1 , M. Hoseinzade 2 Abstract In this study, we used TiO 2 thin films doping with Au, Ag or Cu nanoparticles to increase absorption efficiency in a solar cell system. RF Sputtering method was used to prepare four different samples of thin films (TiO 2 -Au, TiO 2 -Ag, TiO 2 -Cu, and TiO 2 -Au-Ag-Cu). In fact, nanoparticles with different sizes can absorb different wavelength, in preparing samples we used nanoparticles with different grain size in the range of 1-50nm to increase the light absorption by cells. The UV–vis spectra were obtained by UV–Visible spectrophotometer to determine absorption, bad gap variation and conducting of thin films. X-ray diffractometer (XRD) was used to characterize the crystalline structure of the films. In addition, surface morphologies of the films were observed by scanning electron microscopy (SEM). Results show a high absorption efficiency of our samples to compare to other studies. Moreover, sample D (see Table 1) among all of three different nanoparticles has the highest absorption efficiency. Key words: Thin films, Titanium dioxide, RF Sputtering, Nanoparticles, Absorption efficiency 1 . Islamic Azad University-Central Tehran branch, Tehran, Iran 2 . Payam Noor University, Mashhad ,Iran