Research Article Influence of Pore Size on the Optical and Electrical Properties of Screen Printed TiO 2 Thin Films Dinfa Luka Domtau, 1,2 Justus Simiyu, 1 Elijah Omollo Ayieta, 1 Godwin Mwebeze Asiimwe, 1 and Julius Mwakondo Mwabora 1 1 Department of Physics, University of Nairobi, Nairobi, Kenya 2 Department of Physics, University of Jos, Jos, Nigeria Correspondence should be addressed to Dinfa Luka Domtau; domtaudinfa@gmail.com Received 8 July 2016; Revised 24 August 2016; Accepted 5 September 2016 Academic Editor: Kaveh Edalati Copyright © 2016 Dinfa Luka Domtau et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Infuence of pore size on the optical and electrical properties of TiO 2 thin flms was studied. TiO 2 thin flms with diferent weight percentages (wt%) of carbon black were deposited by screen printing method on fuorine doped tin oxide (FTO) coated on glass substrate. Carbon black decomposed on annealing and artifcial pores were created in the flms. All the flms were 3.2 m thick as measured by a surface profler. UV-VIS-NIR spectrophotometer was used to study transmittance and refectance spectra of the flms in the photon wavelength of 300–900 nm while absorbance was studied in the range of 350–900 nm. Band gaps and refractive index of the flms were studied using the spectra. Refectance, absorbance, and refractive index were found to increase with concentrations of carbon black. Tere was no signifcant variation in band gaps of flms with change in carbon black concentrations. Transmittance reduced as the concentration of carbon black in TiO 2 increased (i.e., increase in pore size). Currents and voltages (-) characteristics of the flms were measured by a 4-point probe. Resistivity () and conductivity () of the flms were computed from the - values. It was observed that resistivity increased with carbon black concentrations while conductivity decreased as the pore size of the flms increased. 1. Introduction Te interest of material scientists in titanium dioxide is on the increase due to its potentials in a wide range of industrial applications. TiO 2 with a wide band gap of 3.2eV has attracted considerable interest because of the outstanding properties of its thin flms such as electrical, optical, and chemical properties. Tese properties include high conduc- tivity, high refractive index, and high transparency in the visible region. Tus TiO 2 is useful in applications such as photocatalyst [1], dye sensitized solar cells [2], chemical sensors [3–5], electrochromics [6], and electronic devices [7]. Te quality of the TiO 2 flm is infuenced by the type of material and method used for flm deposition and subsequent sintering procedure. Te properties of the flms such as surface area, roughness, and pore size and flm thickness are responsible for its surface and electronic properties. Cho et al. presented a simple architecture that achieves enhanced light scattering in TiO 2 flms [8]. Polystyrene (PS) spheres of submicrometer size were incorporated into the TiO 2 paste resulting in photoanode with bimodal pore size distribution. Te optical properties of the flms were improved by the enhancement of the flms’ pore size. Furthermore, TiO 2 flms with artifcial pores formed using acetylene black to improve the light scattering flms without a light scattering layer have also been fabricated [9]. Te artifcial flms were found to improve the refectance of the flms. Te dependence of optical properties of TiO 2 thin flms has been reported to depend on pore size [10, 11]. Refractive index and electrical resistivity were found to depend on porosity of the flms and bandgap was found to depend on annealing temperature and grain size. However, the efect of pore size on the optical and electrical properties of TiO 2 thin flms especially for optimum applications in dye sensitized solar cells has not Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2016, Article ID 7515802, 7 pages http://dx.doi.org/10.1155/2016/7515802