| 1. |
- He, J. J., et al.
(författare)
-
Phthalocyanine-sensitized nanostructured TiO2 electrodes prepared by a novel anchoring method
- 2001
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 17:9, s. 2743-2747
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method for anchoring phthalocyanines substituted with ester groups onto nanostructured TiO2 films is described. Such phthalocyanines did not adsorb on nanostructured TiO2 film by the ordinary methods. In our new method, the TiO2 film is pretreated with (CH3)(3)COLi to change the surface hydroxyl groups (-OH) into oxygen anions (-O-), thus making the surface more reactive toward the ester functionalities of the dye. The dye can then be anchored onto the semiconductor surface through the produced carboxylate group(s). The amount of anchored dye on the semiconductor shows a dependence on both the time of base treatment and the time of dye treatment. Electrodes treated with the free base phthalocyanine and zinc phthalocyanine were characterized by absorption spectroscopy, photocurrent action spectroscopy, and photocurrent-photovoltage measurements. The homogeneous blue-green color and the absorption bands in the far-red region are indicative of an attachment of the dye on TiO2 film. A monochromatic incident photo-to-current conversion efficiency of 4.3 % was achieved at 690 nm for a cell where the base-treated electrode was treated with ZnPcBu.
|
|
| 2. |
- He, Jianjun, et al.
(författare)
-
Modified phthalocyanines for efficient near-IR sensitization of nanostructured TiO2 electrode
- 2002
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 124:17, s. 4922-4932
-
Tidskriftsartikel (refereegranskat)abstract
- A zinc phthalocyanine with tyrosine substituents (ZnPcTyr), modified for efficient far-red/near-IR performance in dye-sensitized nanostructured TiO2 solar cells, and its reference, glycine-substituted zinc phthalocyanine, (ZnPcGly), were synthesized and characterized. The compounds were studied spectroscopically, electrochemically, and photoelectrochemically. Incorporating tyrosine groups into phthalocyanine makes the dye ethanol-soluble and reduces surface aggregation as a result of steric effects. The performance of a solar cell based on ZnPcTyr is much better than that based on ZnPcGly. Addition of 3alpha,7alpha-dihydroxy-5beta-cholic acid (cheno) and 4-tert-butylpyridine (TBP) to the dye solution when preparing a dye-sensitized TiO2 electrode diminishes significantly the surface aggregation and, therefore, improves the performance of solar cells based on these phthalocyanines. The highest monochromatic incident photo-to-current conversion efficiency (IPCE) of similar to24% at 690 nm and an overall conversion efficiency (eta) of 0.54% were achieved for a cell based on a ZnPcTyr-sensitized TiO2 electrode. Addition of TBP in the electrolyte decreases the IPCE and eta considerably, although it increases the open-circuit photovoltage. Time-resolved transient absorption measurements of interfacial electron-transfer kinetics in a ZnPoTyr-sensitized nanostructured 702 thin film show that electron injection from the excited state of the dye into the conduction band of TiO2 is completed in similar to500 fs and that more than half of the injected electrons recombines with the oxidized dye molecules in similar to300 ps. In addition to surface aggregation, the very fast electron recombination is most likely responsible for the low performance of the solar cell based on ZnPcTyr.
|
|
| 3. |
- Yanagisawa, M., et al.
(författare)
-
Synthesis of phthalocyanines with two carboxylic acid groups and their utilization in solar cells based on nanostructured TiO2
- 2004
-
Ingår i: Journal of Porphyrins and Phthalocyanines. - 1088-4246 .- 1099-1409. ; 8:10, s. 1228-1235
-
Tidskriftsartikel (refereegranskat)abstract
- A way of anchoring unsymmetrical phthalocyaninato-metal complexes (metal ion: zinc and ruthenium) is described. The synthesis and characterization of these complexes are presented. In case of the zinc complex, the obtained product is an aggregate, while only the monomer is obtained in the case of the ruthenium derivative. Both complexes could be attached onto the TiO2 surface by using the reported method. Both dyes are expected to form monolayers with dye molecules standing on the surface of nano-structured TiO2, forming higher-order aggregates with the zinc but not with the ruthenium complex. A highest monochromatic incident photo-to-current conversion efficiency (IPCE) of 1.6% at 690 nm was obtained for a solar cell based on the Pc-Zn sensitized nano-structured TiO2 electrode, while an IPCE of 23% at 630 nm was obtained for the Pc-Ru sensitized electrode. Overall conversion efficiencies (eta) at a simulated AM 1.5 (100 W.m(-2)) of 0.03% and 0.40% for the zinc and ruthenium complexes were achieved, respectively. The difference in efficiencies could be due to the formation of face-to-face aggregation in the former case. This work shows that the ruthenium complex, with two axial methylpyridine ligands, does not form aggregates in solution nor on the surface of TiO2, making it possible for further construction of supramolecular systems with such types of phthalocyanine.
|
|
