Improved performance of dense TiO2/CdSe coupled thin films by low temperature process

Abstract

Dense TiO2 and TiO2/CdSe coupled nanocrystalline thin films were synthesized onto ITO coated glass substrate by chemical route at relatively low temperature (<= 100 degrees C). TiO2 films were nanocrystalline and crystallinity disappears after CdSe deposition as evidenced by X-ray powder diffraction. Surface morphology and physical appearance of films were studied from SEM and actual photo-images, reveals dense nature of TiO2 (10-12 nm spherical grains, faint violet) and CdSe (80-90 nm spherical grains, deep brown), respectively. Presence of two absorption edges in UV spectra implies existence of separate phases rather than composite formation. TiO2 film was found to have higher water contact angle (71 degrees) than TiO2/CdSe (61 degrees) and CdSe (56 degrees). I-V and stability tests of photo-electrochemical cells were performed with TiO2 and TiO2/CdSe film electrodes (under light of illumination intensity 80 mW/cm(2)) in lithium iodide as an electrolyte using two-electrode system. (c) 2004 Elsevier Ltd. All rights reserved.