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Open Access Nano Express

TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells

Woong-Rae Kim1, Hun Park2 and Won-Youl Choi13*

  • * Corresponding author: Won-Youl Choi cwy@gwnu.ac.kr

  • † Equal contributors

Author Affiliations

1 Department of Metal and Materials Engineering, Gangneung-Wonju National University, Gangneung 210-720, South Korea

2 Photovoltaic Research Department, Green Energy Research Institute, Hyundai Heavy Industries Co., Ltd, Yongin 446-912, South Korea

3 Research Institute for Dental Engineering, Gangneung-Wonju National University, Gangneung 210-720, South Korea

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Nanoscale Research Letters 2014, 9:93  doi:10.1186/1556-276X-9-93

Published: 24 February 2014

Abstract

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current (Jsc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved Jsc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure.

Keywords:
Dye-sensitized solar cells; TiO2 nanotube; Micro-flowers; Anodizing