(397ai) Synthesis of High Aspect-Ratio ZnO Nanowires By Both 2-Step Cbd and CVD Methods

Synthesis of High
Aspect-Ratio ZnO Nanowires by

Both 2-step CBD and CVD Methods

Yang Zhao^1,*, Cheng Xu^1,2, Jie Liu¹,
Yongjie Zou², and Kirk J. Ziegler^1,2

¹ Department of Chemical
Engineering

² Department of
Materials Science and Engineering

University
of Florida, Gainesville, FL 32611*Presenting
Author (Ph: 352-392-3122;
Email: yangzhao@ufl.edu)

Abstract: 

Dye-sensitized solar
cells (DSSCs) have been extensively studied for the past few years because of their low-cost and high-efficiency. The surface area of the photoanode,
which determines the amount of photons absorbed,
is one of the most critical factors to improve the efficiency
of DSSCs. Although conventional TiO₂
nanoparticle-based DSSCs have shown promising results, their performance has
been limited to ~11% because of diffusion and back reaction problems.  Due to its excellent band gap (3.37eV) and high excitation
bonding energy (60 meV) properties, one-dimensional (1D) ZnO nanowires are capable of
overcoming the limitation of nanoparticle-based DSSCs by improving electron
injection and axial electron diffusion. Based on
models proposed by our group, the efficiency of DSSCs based on TiO₂ core-shell
ZnO nanowires (40 µm in
lengths, 40 nm in diameter and ~10¹¹ /cm²of density) can significantly surpass current efficiencies. To reach
our objective, we focused
on using two-step anodized aluminum oxide (AAO) as a template to control the dimension
of nanowires. The synthesis of ZnO nanowires was carried out both in 2-step chemical bath deposition method and using thermal decomposition of zinc acetate dehydrate in the
AAO pores by low temperature, catalyst-free vapor-solid (VS) growth. After transferring embedded ZnO nanowires to a PDMS
substrate, AAO was etched and an electrostatic repulsion technique was applied
to provide vertically-aligned ZnO nanowires. After that, SEM, TEM, and XRD were
applied to characterize these nanowires. By using this technique, it provides a
new approach to obtain vertically-aligned ZnO nanowires with both high density
and aspect-ratio through a large-scale process.

Keywords: Dye sensitized solar
cell (DSSC), ZnO Nanowires,
Alumina Template, Thermal Decomposition.