Controlling electron recombination in nanowire-based DSSCs

4^th International Conference and Exhibition on Materials Science & Engineering

September 14-16, 2015 Orlando, USA

Kirk J Ziegler, Luping Li, Cheng Xu and Yang Zhao

University of Florida, USA

ScientificTracks Abstracts-Workshop: J Material Sci Eng

Abstract :

Electron recombination in dye-sensitized solar cells (DSSCs) results in significant electron loss and performance degradation. To our knowledge, the reduction of electron recombination via blocking layers in nanowire-based DSSCs has never been investigated. In this study, HfO2 or TiO2 blocking layers are deposited on nanowire surfaces via atomic layer deposition (ALD) to reduce electron recombination in nanowire-based DSSCs. The control cell consisting of ITO nanowires coated with a porous shell of TiO2 by TiCl4 treatment yields an efficiency of 2.82%. The efficiency increases dramatically to 5.38% upon the insertion of a 1.3 nm TiO2 compact layer between the nanowire surface and porous TiO2 shell. This efficiency enhancement implies that porous sol-gel coatings on nanowires (e.g., via TiCl4 treatment) result in significant electron recombination in nanowire-based DSSCs while compact coatings formed by ALD are more advantageous because of their ability to act as a blocking layer. While the insertion of a high band-gap compact layer of HfO2 between the interface of the conductive nanowire and TiO2 shell improves performance, a comparison of the cell performance between TiO2 and HfO2 compact layers indicates that charge collection is suppressed by the difference in energy states. Consequently, the use of high band-gap materials at the interface of conductive nanowires and TiO2 is not recommended.

Biography :

Kirk J Ziegler joined the Chemical Engineering Department at the University of Florida in 2005. His research group focuses on understanding the role of interfaces in onedimensional nanostructures, such as single wall carbon nanotubes (SWCNTs) and vertical arrays of nanowires. His work on SWCNTs has focused on understanding the effect of surfactant-nanotube interactions on dispersion and separation processes. His work on nanowire arrays has applications in energy-related devices, which requires high surface area to maximize energy generation or storage.

Email: kziegler@che.ufl.edu