Siegers Conrad, Würfel Uli, Zistler Markus, Gores Heiner, Hohl-Ebinger Jochen, Hinsch Andreas, Haag Rainer
Chemistry Department, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada.
Chemphyschem. 2008 Apr 4;9(5):793-8. doi: 10.1002/cphc.200700864.
A new, extremely simple concept for the use of energy transfer as a means to the enhancement of light absorption and current generation in the dye solar cell (DSC) is presented. This model study is based upon a carboxy-functionalized 4-aminonaphthalimide dye (carboxy-fluorol) as donor, and (NBu4)2[Ru(dcbpy)2(NCS)2] (N719) as acceptor chromophores. A set of three different devices is assembled containing either exclusively carboxy-fluorol or N719, or a mixture of both. This set of transparent devices is characterized via IV-measurements under AM1.5G and monochromatic illumination and their light-harvesting and external quantum efficiencies (LHE and EQE, respectively) are determined as well. It is shown that the device containing only the donor chromophore has a marginal power conversion efficiency, thus indicating that carboxy-fluorol is a poor sensitizer for the DSC. Cyclovoltametric measurements show that the poor sensitization ability arises from the kinetic inhibition of electron injection into the TiO2 conduction band. Comparing the spectral properties of the DSCs assembled presently, however, demonstrates that light absorbed by carboxy-fluorol is almost quantitatively contributing to the photocurrent if N719 is present as an additional sensitizer. In this case, N719 acts as a catalyst for the sensitization of TiO2 by carboxy-fluorol in addition to being a photosensitizer. Evaluation of the maximum output power under blue illumination shows that the introduction of an energy-donor moiety via coadsorption, leads to a significant increase in the monochromatic maximum output power. This result demonstrates that energy transfer between coadsorbed chromophores could be useful for the generation of current in dye-sensitized solar cells.
提出了一种全新且极其简单的概念，即利用能量转移来增强染料太阳能电池（DSC）中的光吸收和电流产生。该模型研究基于一种羧基官能化的4-氨基萘二甲酰亚胺染料（羧基荧光素）作为供体，以及（NBu4）2[Ru（dcbpy）2（NCS）2]（N719）作为受体发色团。组装了一组三个不同的器件，分别只包含羧基荧光素或N719，或者两者的混合物。通过在AM1.5G和单色光照下的IV测量对这组透明器件进行表征，并确定它们的光捕获效率和外量子效率（分别为LHE和EQE）。结果表明，仅包含供体发色团的器件具有极低的功率转换效率，这表明羧基荧光素是DSC的不良敏化剂。循环伏安测量表明，这种不良的敏化能力源于电子注入TiO2导带的动力学抑制。然而，比较目前组装的DSC的光谱特性表明，如果存在N719作为额外的敏化剂，羧基荧光素吸收的光几乎定量地对光电流有贡献。在这种情况下，N719除了作为光敏剂外，还作为羧基荧光素敏化TiO2的催化剂。对蓝色光照下的最大输出功率评估表明，通过共吸附引入能量供体部分会导致单色最大输出功率显著增加。这一结果表明，共吸附发色团之间的能量转移可能有助于染料敏化太阳能电池中的电流产生。
