Upgradation of local beach sand titania and synthesis of nanocrystalline titania thin film for solar cell application

Abstract

In this work, investigations have been carried out to upgrade titanium dioxide from local beach sand of Cox’s Bazar Bangladesh, to prepare mesoporous film using the upgraded titanium dioxide so that its potential in solar cell applications could be examined. Raw sand was collected from Beach Sand Minerals Exploitation Center in Cox’s Bazar, upgraded into titanium dioxide, among which, selected samples were used to prepare mesoporous films to be used in Dye sensitized Solar Cell. Mineral and phase identification of the raw sand was performed by analyzing it via X-Ray Diffraction, X-Ray Fluorescence and Polarizing Microscopy; and the upgraded titania samples were analyzed based on the structure, composition, morphology and optical property via X-Ray Diffraction, Scanning Electron Microscopy, UV-Vis spectroscopy, respectively. The upgradation was carried out through the route of HCl leaching - H_2 SO_4 decomposition - water leaching – condensation dilution - calcination route with varying decomposition time. In this route, upgradation up to 98% TiO_2 was obtained though the yield was inconsistent. Modified route of HCl leaching - H_2 SO_4 decomposition - water leaching – hydrolysis - calcination resulted in consistent yield and upgradation up to 98.4% TiO_2 for the 900℃ calcined samples and up to 87.8% for 500℃ calcined samples. S, P, Si, Fe etc. were identified in the upgraded titania as impurities and the optical band gap energy was in the range of 2.99 to 3.13eV, while the carrier density was about 1012/cm3. In the later mentioned route, acid concentration of decomposition was varied and obtained titanium dioxide was used to prepare mesoporous films using screen printing method and then films were used as anode in assembled dye sensitized solar cell. Compared to the photon conversion efficiency of the solar cell prepared with commercial titanium dioxide, efficiency up to 52.3% was obtained using the