The design of dyes for panchromatic light absorption has attracted much attention in the field of dye-sensitized solar cells (DSSCs). An approach to enhance panchromatic light absorption utilizes mixtures of complementary light-absorbing dyes as well as dyes with specific anchoring groups that facilitate interfacial charge transfer with TiO2 . Dipole-dipole interactions between the dye molecules on the surface broaden the spectrum, which results in decreased DSSC device performance. However, controlled aggregation of dyes results in broadening the spectral profile along with enhanced photocurrent generation. To control the dye-dye interaction, dimeric dyes with different dipole lengths D1 -Dsq , Dsq -Dsq were systematically designed and synthesized. The photophysical and electrochemical properties were evaluated and the EHOMO and ELUMO levels were determined; these energy levels determines the electron injection from ELUMO of the dye to ECB of TiO2 and regeneration of oxidized dye by the electrolyte, respectively. The absorption spectra of Dsq -Dsq , D1 -Dsq were broadened in solution compared to model dye Dsq ; this indicates that the dye-dye interaction is prominent in solution. In D1 -Dsq excitation energy transfer between photoexcited D1 and Dsq was explained by using Förster resonance energy transfer (FRET). The homodimeric dye showed a device performace of 2.8 % (Voc 0.607, Jsc 6.62 mA/cm2 , ff 69.3 %),whereas the heterodimeric dye D1 -Dsq showed a device performance of 3.9 % (Voc 0.652 V, Jsc 8.89 mA/cm2 , ff 68.8 %). The increased photocurrent for D1 -Dsq is due to the panchromatic IPCE response compared to Dsq -Dsq . The increased Voc is due to the effective passivation of the TiO2 surface by the spirolinker, and the effective dipole moment that shifts the conduction band on TiO2 . Hence, the open circuit potential, Voc , for the devices prepared from Dsq , D1 -Dsq and Dsq -Dsq were systematically modulated by controlling the intermolecular π-π and intramolecular dipole-dipole interactions of the dimeric dyes.

中文翻译：

---

染料敏化太阳能电池的同二聚和异二聚染料：全色光吸收和调制开路电势。

用于全色光吸收的染料的设计在染料敏化太阳能电池（DSSC）领域引起了很多关注。一种增强全色光吸收的方法是利用互补的光吸收染料以及具有特定锚固基团的染料的混合物，这些染料可促进与TiO2的界面电荷转移。表面上的染料分子之间的偶极-偶极相互作用扩大了光谱范围，从而导致DSSC器件性能下降。然而，染料的受控聚集导致光谱分布变宽以及光电流产生增强。为了控制染料与染料的相互作用，系统地设计和合成了具有不同偶极长度D1-Dsq，Dsq-Dsq的二聚染料。评估了其光物理和电化学性质，并确定了EHOMO和ELUMO含量。这些能级分别决定了从染料的ELUMO向TiO2的ECB的电子注入以及电解质对氧化的染料的再生。与模型染料Dsq相比，Dsq -Dsq，D1 -Dsq在溶液中的吸收光谱变宽; 这表明染料与染料的相互作用在溶液中很明显。在D1-Dsq中，通过使用Förster共振能量转移（FRET）解释了光激发D1和Dsq之间的激发能转移。同二聚体染料显示器件性能为2.8％（Voc 0.607，Jsc 6.62 mA / cm2，ff 69.3％），而异二聚体染料D1-Dsq显示器件性能为3.9％（Voc 0.652 V，Jsc 8.89 mA / cm2， ff 68.8％）。与Dsq -Dsq相比，D1-Dsq的光电流增加是由于全色IPCE响应。Voc的增加归因于螺线管对TiO2表面的有效钝化，以及有效的偶极矩，该矩改变了TiO2上的导带。因此，通过控制二聚体染料的分子间π-π和分子内偶极-偶极相互作用，系统地调节了由Dsq，D1-Dsq和Dsq-Dsq制备的器件的开路电势Voc。