Sol-Gel Titanium Dioxide Blocking Layers for DyeSensitized Solar Cells: Electrochemical Characterization

被引:38
作者
Kavan, Ladislav [1 ,2 ]
Zukalova, Marketa [1 ]
Vik, Ondrej [2 ]
Havlicek, David [2 ]
机构
[1] Acad Sci Czech Republ, J Heyrovsky Inst Phys Chem, Vvi, CR-18223 Prague 8, Czech Republic
[2] Charles Univ Prague, Dept Inorgan Chem, Fac Sci, Prague 12841 2, Czech Republic
关键词
cyclic voltammetry; dye-sensitized solar cells; electrochemical impedance spectroscopy; sol-gel method; titanium dioxide; MOTT-SCHOTTKY ANALYSIS; TIO2; FILMS; NANOCRYSTALLINE TIO2; THIN-FILMS; PERFORMANCE; ANATASE; RUTILE; ELECTRODES; DEPOSITION;
D O I
10.1002/cphc.201400026
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Compact, thin TiO2 films are grown on F-doped SnO2 (FTO) by dip-coating from precursor solutions containing poly(hexafluorobutyl methacrylate) or hexafluorobutyl methacrylate as the structure-directing agents. The films are quasi-amorphous, but crystallize to TiO2 (anatase) upon heat treatment at 500 degrees C in air. Cyclic voltammetry experiments performed using Fe(CN)(6)(3-/4-) or spiro-OMeTAD as model redox probes selectively indicate the pinholes, if any, in the layer. The pinhole-free films on FTO represent an excellent rectifying interface at which no anodic faradaic reactions occur in the depletion state. The flat-band potentials of the as-grown films are upshifted by 0.2-0.4 V against the values predicted for a perfect anatase single-crystal surface, but they still follow the Nernstian pH dependence. The optimized buffer layer is characterized by a combination of quasi-amorphous morphology (which is responsible for the blocking function) and calcination-induced crystallinity (which leads to fast electron injection and electron transport in the conduction band). The latter manifests itself by a reversible charging of the chemical capacitance of TiO2 in its accumulation state. The capacitive-charging capability and pinhole formation significantly depend on the post-deposition heat treatment.
引用
收藏
页码:1056 / 1061
页数:6
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