1. Highly ordered and vertically oriented TiO2/Al2O3 nanotube electrodes for application in dye-sensitized solar cells
- Author
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Kyeong Hwan Lee, Sun Ha Park, Junyoung Shin, Kyu Seok Han, Myung Mo Sung, Jae-Yup Kim, Nicola Pinna, Yung-Eun Sung, and Jin Soo Kang
- Subjects
Nanotube ,Materials science ,business.industry ,Mechanical Engineering ,Analytical chemistry ,Shell (structure) ,Bioengineering ,General Chemistry ,Atomic layer deposition ,Dye-sensitized solar cell ,X-ray photoelectron spectroscopy ,Mechanics of Materials ,Transmission electron microscopy ,Electrode ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,business ,Layer (electronics) - Abstract
The surface of long TiO2 nanotube (NT) electrodes in dye-sensitized solar cells (DSSCs) was modified without post-annealing by using atomic layer deposition (ALD) for the enhancement of photovoltage. Vertically oriented TiO2 NT electrodes with highly ordered and crack-free surface structures over large areas were prepared by a two-step anodization method. The prepared TiO2 NTs had a pore size of 80 nm, and a length of 23 μm. Onto these TiO2 NTs, an Al2O3 shell of a precisely controlled thickness was deposited by ALD. The conformally coated shell layer was confirmed by high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The open-circuit voltage (V(oc)) of the DSSCs was gradually enhanced as the thickness of the Al2O3 shell of the TiO2/Al2O3 NT electrodes was increased, which resulted from the enhanced electron lifetime. The enhanced electron lifetime caused by the energy barrier effect of the shell layer was measured quantitatively by the open-circuit voltage decay technique. As a result, 1- and 2-cycle-coated samples showed enhanced conversion efficiencies compared to the bare sample.
- Published
- 2014
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