Abstract
Despite the one-dimensional ordering of anodic TiO2nanotube arrays (TNAs), the electron diffusion towards the substrate in TNA-based dye-sensitized solar cells (DSSCs) is comparably slow. The improvement of electron mobility by enhancing TNA crystallinity under high-temperature annealing, however, is infeasible with the existence of Ti metal substrate. Herein, it is shown that, by high temperature (up to 700°C) crystallization of high-quality free-standing TNA membranes, the TNAs can maintain their structure integrity and phase (anatase) stability as a result of the absence of the nucleation sites and the high quality of the membrane obtained by a self-detachment method. The electron transport is much faster (≈4 times) in the 700°C-annealed TNA membranes than that in the 400°C-treated ones for 20 μm-length nanotubes, which is mainly attributed to the improved crystallinity and reduced electron trap states. In spite of slightly reduced dye loading capacity (decreased by ≈30%) in the 700°C-annealed membranes, the superior electron transport leads to a significantly improved efficiency of 7.81% (enhanced by ≈50%). The strategy of manipulating the electron transport dynamics by high temperature treatment on high-quality TNA membranes may open new route for further improvement in the performances of TNA-based DSSCs.
Original language | English |
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Pages (from-to) | 5952-5960 |
Number of pages | 9 |
Journal | Advanced Functional Materials |
Volume | 23 |
Issue number | 47 |
DOIs | |
Publication status | Published - 17 Dec 2013 |
Keywords
- crystallization
- electron transport
- nanotube arrays
- solar cells
- trap states
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Biomaterials
- Condensed Matter Physics
- Electrochemistry