Department of Chemistry and Argon-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
ACS Nano. 2012 Jul 24;6(7):6185-96. doi: 10.1021/nn3015695. Epub 2012 Jun 28.
A doubly coaxial photoanode architecture based on templated SiO(2) aerogels was fabricated on transparent conducting oxides for use in dye-sensitized solar cells (DSSCs). These templates were coated with ZnO via atomic layer deposition (ALD) to yield an electronically interconnected, low-density, high-surface-area, semiconductor framework. Addition of a thin conformal layer of a second metal oxide (alumina, zirconia, or titania) via ALD was found to suppress the dissolution of ZnO that otherwise occurs when it is soaked in alcohol solutions containing acidic dyes used for sensitization or in acetonitrile solutions containing a pyridine derivative and the iodide/tri-iodide (I(-)/I(-)(3)) redox shuttle. Electron transport in SiO(2)-ZnO-TiO(2) photoelectrodes was found to be nearly 2 orders of magnitude faster than in SiO(2)-TiO(2) structures, implying that the interior ZnO sheath serves as the primary electron conduit. In contrast, rates of electron interception by the oxidized form of the redox shuttle were observed to decrease when a TiO(2) shell was added to SiO(2)-ZnO, with the decreases becoming more significant as the thickness of the titania shell increases. These effects lead to improvements in efficiency for DSSCs that utilize I(-)/I(-)(3), but much larger improvements for DSSCs utilizing ferrocene/ferrocenium, a notoriously fast redox shuttle. For the former, overall energy conversion efficiencies maximize at 4.0%. From a variety of experiments, the primary factor limiting aerogel-based DSSC performance is light loss due to scattering. Nevertheless, variants of the doubly coaxial structure may prove useful in devising DSSCs that can achieve excellent energy conversion efficiencies even with fast redox shuttles.
基于模板化 SiO(2)气凝胶的双重同轴光电阳极结构已在透明导电氧化物上制备，用于染料敏化太阳能电池 (DSSC)。这些模板通过原子层沉积 (ALD) 涂覆 ZnO，形成电子互连、低密度、高表面积、半导体框架。通过 ALD 添加第二层金属氧化物（氧化铝、氧化锆或氧化钛）的薄保形层被发现可以抑制 ZnO 的溶解，否则当 ZnO 浸泡在含有用于敏化的酸性染料的醇溶液或含有吡啶衍生物和碘化物/三碘化物 (I(-)/I(-)(3)) 氧化还原穿梭物的乙腈溶液中时，ZnO 会发生溶解。SiO(2)-ZnO-TiO(2)光电管中的电子输运速度比 SiO(2)-TiO(2)结构快近 2 个数量级，这意味着内部 ZnO 护套是主要的电子导管。相比之下，当 TiO(2)壳添加到 SiO(2)-ZnO 中时，观察到氧化形式的氧化还原穿梭剂的电子捕获速率降低，随着 TiO(2)壳的厚度增加，降低幅度变得更加显著。这些效应导致使用 I(-)/I(-)(3)的 DSSC 的效率提高，但对于使用众所周知的快速氧化还原穿梭剂 ferrocene/ferrocenium 的 DSSC 的效率提高更大。对于前者，整体能量转换效率在 4.0%时达到最大值。从各种实验来看，限制气凝胶基 DSSC 性能的主要因素是由于散射导致的光损失。尽管如此，双重同轴结构的变体可能有助于设计即使使用快速氧化还原穿梭剂也能实现优异能量转换效率的 DSSC。
