Detailed Investigations of ZnO Photoelectrodes Preparation for Dye Sensitized Solar Cells

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• 作者：Renata Marczak ; Fabian Werner ; Rameez Ahmad ; Volodymyr Lobaz ; Dirk M. Guldi ; Wolfgang Peukert
• 刊名：Langmuir
• 出版年：2011
• 出版时间：April 5, 2011
• 年：2011
• 卷：27
• 期：7
• 页码：3920-3929
• 全文大小：1092K
• 年卷期：v.27,no.7(April 5, 2011)
• ISSN：1520-5827

文摘

Wurtzite ZnO hexagonal nanopyramids were successfully synthesized in the liquid phase from homogeneous methanolic solutions of zinc acetate and tetramethylammonium hydroxide at an excess of zinc ions. The formation and properties of the nanocrystals were examined as a function of synthesis conditions. No significant influence of the [Zn²⁺]/[OH^{鈭?/sup>] ratio was noticed on the final particle size, in spite of increased amounts of OH鈭?/sup> ions, which tend to accelerate the particle nucleation and growth. Nevertheless, the reactant concentration ratio influences the surface properties of the ZnO nanocrystals. Mesoporous ZnO films were prepared by doctor blading ethanolic pastes containing ZnO nanoparticles and ethyl cellulose onto FTO conductive glass substrate followed by calcination. Additionally, the influence of a plasticizer (triacetin)鈥攗sed during the paste preparation鈥攐n the film quality was investigated. A higher content of ZnO nanoparticles and plasticizer in the pastes improved the film quality. Four different temperatures (i.e., 400, 425, 450, and 475 掳C) were used for the film calcination and their influence on the structural properties of the films was characterized. In principle, increasing the calcination temperature goes hand in hand with an increase of particle size, as well as the pore diameter and reduction of the surface area. Suitable mesoporous films were employed as photoanodes in dye sensitized solar cells (DSSCs). In order to assess the effect of the varied parameters on complete DSSC devices鈥攗sing cis-diisothiocyanato-bis(2,2鈥?bipyridyl-4,4鈥?dicarboxylato) ruthenium(II)bis(tetrabutylammonium (N719) as a sensitizer鈥攊ncident photon to current efficiency (IPCE) and current voltage measurements were carried out. The IPCE measurements confirmed photoinduced electron injection from the dye, reaching IPCE values up to 76%. Furthermore, current鈭抳oltage characteristics of complete cells emphasized the importance of the proper preparation methods and temperatures. These features are important assets for the preparation of nanocrystalline ZnO based photoelectrodes and for improving the DSSC performance.}