Influence of Porphyrinic Structure on Electron Transfer Processes at the Electrolyte/Dye/TiO2 Interface in PSSCs: a Comparison between meso Push鈥揚ull and 尾-Pyrrolic Architectures
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- 作者：Gabriele Di Carlo ; Stefano Caramori ; Vanira Trifiletti ; Roberto Giannuzzi ; Luisa De Marco ; Maddalena Pizzotti ; Alessio Orbelli Biroli ; Francesca Tessore ; Roberto Argazzi ; Carlo A. Bignozzi
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2014
- 出版时间：September 24, 2014
- 年：2014
- 卷：6
- 期：18
- 页码：15841-15852
- 全文大小：544K
- ISSN：1944-8252
文摘
Time-resolved photophysical and photoelectrochemical investigations have been carried out to compare the electron transfer dynamics of a 2-尾-substituted tetraarylporphyrinic dye (ZnB) and a 5,15-meso-disubstituted diarylporphyrinic one (ZnM) at the electrolyte/dye/TiO2 interface in PSSCs. Although the meso push鈥損ull structural arrangement has shown, up to now, to have the best performing architecture for solar cell applications, we have obtained superior energy conversion efficiencies for ZnB (6.1%) rather than for ZnM (3.9%), by using the I鈥?/sup>/I3鈥?/sup>-based electrolyte. To gain deeper insights about these unexpected results, we have investigated whether the intrinsic structural features of the two different porphyrinic dyes can play a key role on electron transfer processes occurring at the dye-sensitized TiO2 interface. We have found that charge injection yields into TiO2 are quite similar for both dyes and that the regeneration efficiencies by I鈥?/sup>, are also comparable and in the range of 75鈥?5%. Moreover, besides injection quantum yields above 80%, identical dye loading, for both ZnB and ZnM, has been evidenced by spectrophotometric measurements on transparent thin TiO2 layers after the same adsorption period. Conversely, major differences have emerged by DC and AC (electrochemical impedance spectroscopy) photoelectrochemical investigations, pointing out a slower charge recombination rate when ZnB is adsorbed on TiO2. This may result from its more sterically hindered macrocyclic core which, besides guaranteeing a decrease of 蟺-staking aggregation of the dye, promotes a superior shielding of the TiO2 surface against charge recombination involving oxidized species of the electrolyte.