Dye-Sensitized Solar Cells based on Titanium Oxide(Ⅳ) Nanotube Arrays

Abstract

We prepared dye-sensitized solar cells (DSSCs) with enhanced energy conversion efficiency using open-ended TiO2 nanotube arrays with a TiO2 scattering layer. As compared to closed-ended TiO2 nanotube arrays, the energy conversion efficiency of the open-ended TiO2 nanotube arrays was increased from 5.63% to 5.92%, which is an enhancement of 5.15%. With the TiO2 scattering layer, the energy conversion efficiency was increased from 5.92% to 6.53%, which is an enhancement of 10.30%. After treating the open-ended TiO2 nanotube arrays with TiCl4, the energy conversion efficiency was increased from 5.92% to 6.89%, a 16.38% enhancement, which is attributed to improved light harvesting and increased dye adsorption.

Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO2 nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO2 NPs to create a scattering effect in order to improve energy conversion efficiency. Compared to closed-ended freestandung TiO2 nanotube array-based DSSCs without Ag or large TiO2 NPs, the energy conversion efficiency of closed-ended DSSCs improved by 9.21%(actual efficiency, from 5.86% to 6.40%) with Ag NPs, 6.48%(actual efficiency, from 5.86% to 6.24%) with TiO2 NPs, and 14.50%(actual efficiency, from 5.86% to 6.71%) with both Ag NPs and TiO2 NPs. By introducing Ag NPs and/or large TiO2 NPs to open-ended freestanding TiO2 nanotube array-based DSSCs, the energy conversion efficiency was improved by 9.15%(actual efficiency, from 6.12% to 6.68%) with Ag NPs and 8.17%(actual efficiency, from 6.12% to 6.62%) with TiO2 NPs, and by 15.20%(actual efficiency, from 6.12% to 7.05%) with both Ag NPs and TiO2 NPs. Moreover, compared to closed-ended freestanding TiO2 nanotube arrays, the energy conversion efficiency of open-ended freestanding TiO2 nanotube arrays increased from 6.71% to 7.05%. We demonstrate that each component—Ag NPs, TiO2 NPs and open-ended freestanding TiO2 nanotube arrays—enhanced the energy conversion efficiency, and the use of a combination of all components in DSSCs resulted in the highest energy conversion efficiency.