Investigation of the Effect of Alkyl Chain Length on Charge Transfer at TiO2/Dye/Electrolyte Interface
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- 作者：Shogo N. Mori ; Wataru Kubo ; Taisuke Kanzaki ; Naruhiko Masaki ; Yuji Wada ; Shozo Yanagida
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：March 1, 2007
- 年：2007
- 卷：111
- 期：8
- 页码：3522 - 3527
- 全文大小：181K
- 年卷期：v.111,no.8(March 1, 2007)
- ISSN：1932-7455
文摘
Dye-adsorbed nanoporous TiO2 films were prepared with Ru(H2dcbpy)(bpy)(NCS)2, Ru(H2dcbpy)(dmbpy)(NCS)2, and Ru(H2dcbpy)(dnbpy)(NCS)2, which have the same structure with different alkyl chain lengths of0, 1, and 9 attached to a bipyridine ligand, and with conventional dyes, Ru(Bu4NHdcbpy)2(NCS)2, known asN719, and Ru(dcb)2(NCS)2, known as N3. The films were immersed in electrolytes containing I-/I3- redoxcouples, and lifetime of conduction band electrons, which were injected from the excited states of the dyes,was measured. When Li+ was employed as a counter charge of the redox couple, no noticeable differencewas observed regardless of the difference of alkyl chain length of the dyes. Transient absorption measurementsof dye cation also showed comparable dye cation lifetime, suggesting that the alkyl chain length of the rutheniumcomplexes has little influence on the charge transfers from TiO2 to I3- and from I- to dye cation. Electronlifetime was also measured for dye-sensitized solar cells (DSCs) using electrolytes containing tetrabuthylammonium or tetrahexylammonium cations instead of Li+. Except for N719, comparable electron lifetimewas observed regardless of the species of the cations, indicating that the alkyl chain length of quaternaryammonium cations also did not influence the interfacial charge transfer. These results show that alkyl chainitself does not impede the approach of I-/I3- anions to the TiO2 surface, but the simultaneous control andconcerted effect of the density of adsorbed dye and the size of cations are important to retard undesiredinterfacial charge transfers.