Cation-Dependent Charge Recombination to Organic Mediators in Dye-Sensitized Solar Cells

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• 作者：Brian N. DiMarco ; Ryan M. O鈥橠onnell ; Gerald J. Meyer
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 17, 2015
• 年：2015
• 卷：119
• 期：37
• 页码：21599-21604
• 全文大小：378K
• ISSN：1932-7455

文摘

Mesoporous TiO₂ thin films sensitized to visible light with [Ru(dtb)₂(dcb)]²⁺, where dtb is 4,4鈥?((CH₃)₃C)₂-2,2鈥?bipyridine and dcb is 4,4鈥?(CO₂H)₂-2,2鈥?bipyridine, abbreviated TiO₂|Ru, were investigated in acetonitrile electrolytes that contained 0.1 M Na⁺, Li⁺, Mg²⁺, or Ca²⁺ perchlorate solutions with the electron donor trip-tolylamine (TPTA) or phenothiazine (PTZ). Pulsed 532 nm light excitation of TiO₂|Ru with >25 mM donor concentrations quantitatively yielded TiO₂(e^{鈥?/sup>)|Ru + D+, and the corresponding recombination reaction between the injected electrons and the oxidized donors was monitored on nanosecond and longer time scales. The recombination kinetics were nonexponential, but were well described by the Kohlrausch鈥揥illiams鈥揥atts stretched exponential function. For the TPTA donor, the abstracted rate constants followed the trend Na+ > Li+ > Mg2+ > Ca2+. A similar trend was seen for PTZ, although no significant difference in the recombination kinetics for Na and Li was observed, Na+ 鈭?Li+ > Mg2+ > Ca2+. The origins of this cation dependence are discussed in terms of the thermodynamic driving force, the electron diffusion lengths of the injected electrons, and the electric field strength present.}