Optical and Structural Properties of TiO₂ and CuAlSe₂ Doped with Carbon Based Graphene for Photovoltaic Devices

The preparation and characterization of copper aluminum diselenide (CuAlSe₂) and Titanium dioxide (TiO₂)-doped with carbon based graphene nanocomposite thin films were examined. The temperature, deposition time, and pH of the medium was varied by spin coating method. Samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDX) and UV visible spectroscopy techniques for the structural, morphological, compositional features and photo-response for photovoltaic devices. The optical property revealed that CuAlSe₂ films have energy band gaps range 2.22-5.80 eV and 2.10-2.14 eV at room and peak temperature. The XRD patterns of CuAlSe thin films showed peaks (101), (102), (006), (110), (108), and (116) corresponding to the formation of hexagonal phase of CuInSe₂ and the particle size D 38.20 nm. XRD pattern of C: CuAlSe₂ and TiO₂flakes were perfectly crystallized and the inter-planar spacing of 0.053 nm. FESEM analysis indicated smooth and uniform structures. The graphene-TiO₂ displayed glistering surfaces due to less density of electronic trap states and improved absorption in the UV region. The resistivity of the samples were 1.95s/m and 12.93s/m for GO and GO-TiO₂. The results indicated that the average electron mobility depends on the probability of the electrons in the conduction band and as the quasi-Fermi level approaches the CB, a higher current, power supply and lower resistivity level.