Integration of TiO₂ nanotube arrays into solid-state dye-sensitized solar cells

¹ Applied Functional Polymers, Department of Macromolecular Chemistry I, University of Bayreuth, 95440 Bayreuth, Germany
² Institute of Fundamental Studies, Hantana Road, CP, 20000 Kandy, Sri Lanka
³ Department of Electrical Engineering, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA

Corresponding author: jayasundera@yahoo.com

Received: 5 October 2010
Accepted: 16 November 2010
Published online: 28 January 2011

Abstract

In this investigation, transparent TiO₂ nanotube arrays prepared on a FTO substrate are employed as 1D nanostructures providing elongated direct pathways for electron transport and collection in solid-state dye-sensitized solar cell (SDSC). Donor-antenna (D-A) dyes provide an exciting route for improving the light harvesting efficiency in dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state. Hence in this study we fabricated SDSC devices with different thicknesses of transparent TiO₂ nanotube array electrodes sensitized with Ru-(II)-donor-antenna dye and spiro-OMeTAD as a hole conductor. At AM 1.5 G, 100 mW/cm² illumination intensity, a power conversion efficiency of 1.94% was achieved when the TiO₂ nanotubes are initially subjected to TiCl₄ treatment. Furthermore, a linear increase in the cell current without loss in fill factor is observed for increasing length of TiO₂ nanotubes. The structural and morphological characteristics of the transparent TiO₂ nanotube arrays as well as the optimal conditions for the fabrication of SDSCs with transparent TiO₂ nanotubes on FTO glass are reported.