標題: Interfacial energy levels and related properties of atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells
作者: Tien, Ta-Chang
Pan, Fu-Ming
Wang, Lih-Ping
Lee, Chia-Hua
Tung, Yung-Liang
Tsai, Song-Yeu
Lin, Ching
Tsai, Feng-Yu
Chen, Su-Jen
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 29-Jul-2009
摘要: Low-temperature (similar to 150 degrees C), atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells (DSSCs) were investigated using electron spectroscopy. The power conversion efficiency (PCE) of the DSSCs was increased from 5.7% to 6.5%, an improvement of 14%, with one monolayer of Al2O3 with a thickness of similar to 0.2 nm. The formation of Ti-O-Al(OH)(2) and interfacial dipole layers exhibited a strong influence on the work function of the Al2O3 over-layers, while the thicker Al2O3 over-layers caused the values of valence band maximum and band gap to approach the values associated with pure Al2O3. A work function difference (Delta Phi(A-T)) of 0.4 eV and a recombination barrier height (epsilon(RB)) of 0.1 eV were associated with the highest PCE achieved by the first monolayer of the Al2O3 layer. Thicker Al2O3 over-layers, however, caused significant reduction of PCE with negative Delta Phi(T-A) and increased interfacial energy barrier height (*epsilon(IB)) between the N719 dyes and TiO2 electrodes. It was concluded that the PCE of the DSSCs may correlate with Delta Phi(A-T), epsilon(RB), and *epsilon(IB) resulting from various thicknesses of the Al2O3 over-layers and that interfacial reactions, such as the formation of Ti-O-Al(OH)(2) and dipole layers, play an important role in determining the interfacial energy levels required to achieve optimal performance of dye-sensitized TiO2 solar cells.
URI: http://dx.doi.org/10.1088/0957-4484/20/30/305201
http://hdl.handle.net/11536/149803
ISSN: 0957-4484
DOI: 10.1088/0957-4484/20/30/305201
期刊: NANOTECHNOLOGY
Volume: 20
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