Dual functionalized freestanding TiO2 nanotube arrays coated with Ag nanoparticles and carbon materials for dye-sensitized solar cells

Abstract

Highly ordered, freestanding TiO2 nanotube arrays (TiO2 NTAs) were prepared using an electrochemical method. The barrier layer was etched to open the bottom of each array, aptly named "open-ended TiO2 NTAs". These arrays were coated with silver nanoparticles (Ag NPs) and/or carbon materials to enhance electron generation and transport. The energy conversion efficiency of the resulting dye-sensitized solar cells (DSSCs) with open-ended freestanding TiO2 NTAs, when coated with Ag NPs, increased from 5.32% to 6.14% (by 15%) due to plasmonic interactions. Meanwhile, coating the open-ended freestanding TiO2 NTAs with carbon materials increased the energy conversion efficiency from 5.32% to 6.07% (by 14%), due to π-π conjugation. When the Ag NPs and carbon materials were simultaneously applied to the open-ended freestanding TiO2 NTAs, the energy conversion efficiency increased from 5.32% to 6.91%-an enhancement of 30%, due to the additive effects of plasmonics and π-π conjugation.