Nanocomposite Dye Sensitized Solar Cell Based on Titanium Oxide/Tungsten Oxide Nanorods Photoelectrode and Polyaniline-Carbon Nanotube Counter Electrode

Abstract

In the operational process of dye sensitized solar cell (DSSC) photo excitation of the sensitizer is followed by electron injection into the conduction band of the mesoporous oxide semiconductor. The dye molecule is regenerated by the redox system, which itself is restored at the counter electrode by electrons passed through the load. Some electrons in conduction band of the photo-electrode travel back to the electrolyte, which results in a loss of efficiency in the DSSC [1-2]. Therefore, it is important to suppress this recombination reaction and to improve the collection of photo-injected electrons for enhancing the cell performance [3]. Tungsten oxide (WO 3 ) is a semiconductor oxide material with a band-gap of 2.6–3.0 eV [3], and it is becoming the focus of research attention due to its unique electronic properties. Various WO 3 nanostructures (nanoparticles, nanoplatelets, nanorods, and nanowires) are of special interest as promising candidate [3, 4] as a photo-electrode. It is well known that polyaniline (PANI) is one of the most promising conducting polymers. Due to its high electrochemical activity, environmental stability and low cost, PANI materials have been employed to fabricate efficient counter electrode in DSSCs [5]. Recently, there is a large interest to incorporate carbon nanotubes (CNTs) into organic solar cells because of the unique electrical properties of CNTs. For example, CNTs were used as electron acceptors in the photoactive layer of the solar cells [6]. Also, CNTs were used as transparent anodes in order to replace the prevailed wildly used indium tin oxide (ITO) [7]. In this work nanomaterials for photo- and counter-electrodes are synthesized and investigated. The morphological structures of WO 3 nanorods deposited onto TiO 2 nanoparticles and PANI-CNTs. The electro-catalytic activity of the counter electrode is investigated using cyclic voltammetry technique. The CNTs blended PANI base counter electrode and ruthenium dye sensitized WO 3 /TiO 2 based photo-electrode were assembled to form DSSC. The electrical properties of the fabricated solar cells were investigated by measuring the current density voltage (J–V) under both darkness and illumination conditions. It was found that there is a significant improvement in the performance of DSSC used WO 3 nanorods. References 1 M. Grätzel, Journal of Photochemistry and Photobiology Photochemistry R eviews 4 , 145–153 (2003). 2 S. M. Yong, T. Nikolay, B. T. Ahn, D. K. Kim, Journal of Alloys and Compounds 54 , 113–117(2013). 3 F.G. Wang, C. Di Valentin, G. Pacchioni, Chemcatchem 4 476–478(2012). 4 H.D. Zheng, Y. Tachibana, K. Kalantar-zadeh, Langmuir 26 19148–19152 (2010). 5 G. Wang, W. Xing, S. Zhuo, Electrochimica Acta 66 , 151– 157. (2012). 6 S Berson., D. Bettignies., S. Bailly, S. Guillerez, B. Jousselme, Adv. Funct. Mater . 17 , 3363–3370 (2007). 7 E. Kyamakis, E. Stratakis, E. Koudoumas, Thin Solid Films 515 8598–8600(2007).