Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
J Colloid Interface Sci. 2012 Apr 15;372(1):73-9. doi: 10.1016/j.jcis.2012.01.004. Epub 2012 Jan 18.
Photovoltaic properties of Ru(2,2'-bipyridine-4,4'-bicarboxylic acid)(4,4'-bis(11-dodecenyl)-2,2'-bipyridine)(NCS)(2) (denoted as Ru-C) related to its adsorption behavior onto the mesoporous titanium oxide (TiO(2)) were investigated in association with its amphiphilic structure compared with those of Ru(4,4'-dicarboxy-2,2'-bipyridine)(2)(NCS)(2) (commonly known as N3 dye). Both dyes tended to aggregate and form vesicles in their acetonitrile/tert-butanol solutions. As the vesicles were adsorbed to TiO(2), the dyes which did not participate in bonding to TiO(2) would re-dissolve into the solution and create the voids on the surface of TiO(2). The voids for N3 dyes would be filled in time, whereas a great deal of voids for Ru-C dye remained, presumably due to its aliphatic side chains retarding further adsorption. The dye sensitized solar cell (DSSC) using Ru-C dye has lower power conversion efficiency compared with N3 dye, which is partly due to the remaining voids that increase the charge recombination. Besides, the N3 dye that is capable of injecting the excited electrons from both ligands to TiO(2) also enhances the photocurrent. Therefore, although using amphiphilic dye for DSSC may have a merit of long term stability, its tendency of void formation on TiO(2) mesoporous layer needs to be concerned.
Ru(2,2'-联吡啶-4,4'-二甲酸)(4,4'-双(11-十二烯基)-2,2'-联吡啶)(NCS)(2)（表示为 Ru-C）与 TiO(2)介孔的吸附行为相关的光伏性能，以及其与两亲性结构的关系，与 Ru(4,4'-二羧酸-2,2'-联吡啶)(2)(NCS)(2)（通常称为 N3 染料）进行了比较。两种染料在乙腈/叔丁醇溶液中都倾向于聚集并形成囊泡。当囊泡被吸附到 TiO(2)上时，未参与与 TiO(2)键合的染料会重新溶解在溶液中，并在 TiO(2)表面上产生空隙。N3 染料的空隙会及时填充，而 Ru-C 染料的大量空隙仍然存在，可能是由于其脂肪侧链阻碍了进一步的吸附。使用 Ru-C 染料的染料敏化太阳能电池（DSSC）的功率转换效率低于 N3 染料，部分原因是增加了电荷复合的剩余空隙。此外，能够从两个配体向 TiO(2)注入激发电子的 N3 染料也增强了光电流。因此，尽管使用两亲性染料制造 DSSC 可能具有长期稳定性的优点，但需要关注 TiO(2)介孔层中形成空隙的趋势。
