Fabrication of single-layered and double-layered TiO2 nanotube arrays for dye-sensitized solar cells

• Main Author: Sie, Dickson Aik Chee.
• Other Authors: Sam Zhang Shanyong
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials::Composite materials
• Online Access: http://hdl.handle.net/10356/53978
• Institution: Nanyang Technological University

Advantages of titanium dioxide have allowed it to be a replacement to the conventional solar cells by the means of dye-sensitized solar cells (DSSCs). Nanotubular arrays have high surface-to-volume ratio, allowing a larger surface area to be dye-loaded to as compared to conventional nanocrystalline DSSC. Nanotubular arrays are more favourable to other structures due to its fast charge transport property that does not allow electron scattering and they promote light scattering within the structure. It is known that the efficiency of titanium dioxide nanotube arrays are affected by the geometrical aspects of the nanotubes, especially the length, diameter and compactness. Only single-layered nanotube-based DSSCs are reported till date. This project investigates the performance of both single-layered and double-layered nanotube-based DSSC which includes fabrication of three structures of nanotubes and to measure their corresponding DSSC performances. For this project, different geometrical structures of nanotubes will be designed and experimented to come up with an optimal nanotubular structure. The first structure will be a conventional single-layered nanotube array anodized at a higher voltage of 50V. A second structure will be a double-layered nanotube array consisting of larger nanotube diameter at the upper portion and smaller nanotube diameter at the bottom (50V – 25V) by varying the potential voltage during anodization from 50V to 25V. The last structure would be another double-layered structure that has smaller diameter at its upper portion while larger diameter at the lower portion (25V – 50V) by increasing the potential voltage from 25V to 50V. All structures will be assembled into DSSC and tested for their efficiency. Results have shown that both single layered nanotube arrays produces the best efficiency, followed by double-layered (25V – 50V) nanotube arrays. The lowest efficiency obtained are projected from double-layered (50V – 25V) nanotube arrays with efficiency of 7% lower than double-layered (25V – 50V) and 8% lower than the single-layered nanotube arrays. In conclusion, not only do single-layered nanotube arrays have the best efficiency, the time required to grow them is one-fifth that of double-layered nanotube arrays, indubitably saving a lot of time in large-scale projects