非平面多元发色团染料敏化TiO2电极界面的能量/电荷迁移机理

Dye-sensitized semiconductor electrode has been applied to various applications. Promoted in recent years, un-planar sensitizers showed superior abilities in both light harvesting and blocking electron recombination at dye-sensitized semiconductor interface as compared to the conjugated single chromophoric sensitizers. Nonetheless, the use of un-planar di-chromophoric sensitizers in dye-sensitized solar cells has not attained acceptable power conversion efficiencies as anticipated. This is mainly due to the lack of understanding on the properties at dye-sensitized semiconductor interface, especially where cascade and competitive energy / charge transfer processes being involved. The project aims to explore the utility of un-planar multi-chromophoric concept by investigating energy / charge transfer mechanisms in dye-sensitized TiO2 electrodes. To this end, a series of multi-chromophoric sensitizers are rational designed and their photophysical and photochemical properties will be examined. In particular, the effect of tailoring molecular structure, such as tuning energy levels of each chromophore and introducing tri-dimensional donor moiety to the outside chromophore, on energy / charge transfer processes in dye-sensitized TiO2 electrodes will be thoroughly explored.

染料敏化半导体电极在多个领域有着广泛的应用价值。非平面结构染料作为一种新型染料，相较于共轭平面结构的单一发色团染料，在增加光捕捉和抑制半导体电极界面的电子复合等方面具有显著优势。然而，由于对非平面结构染料敏化半导体电极界面反应，尤其对发色团之间发生级联和竞争能量/电荷迁移机理的研究不足，非平面二元发色团染料在染料敏化太阳能电池中的性能明显低于预期。进一步深化电极界面的能量/电荷迁移机理研究，对于提升半导体电极性能至关重要。基于此，本项目将设计合成不同分子结构的非平面多元发色团染料，研究该类染料在溶液中及TiO2表面上的光物理和光化学性质；着重研究分子结构变化，尤其是改变发色团能级关系和链接三维结构电子给体等，对染料敏化TiO2界面的能量/电荷迁移的影响；完善非平面结构染料的设计理念，从而为该类分子在染料敏化半导体电极的实际应用提供理论支持。

本项目旨在完善非平面结构染料在界面电荷迁移的作用机理。为此，我们设计并合成了一系列具有不同功能的非平面二元/多元发色团染料，并分别在染料敏化太阳能电池、光催化、电催化和荧光探针中进行了相关机理研究和应用探索。结果表明，非平面多元发色团染料分子内能量迁移对染料敏化半导体电极的光电性能有较大影响；利用分子内电荷迁移开发的荧光探针具有较高的灵敏度和抗干扰性，在生物定量检测中效果良好。此外，我们应用探索了具有三维空间结构的三苯胺对电催化界面反应过程的作用，证实了三苯胺更多暴露的分子轨道有利于促进界面反应动力学。通过项目开展，深化了非平面结构染料的设计理念，为后续该类分子在光电化学器件、光电催化以及传感器等领域应用提供了理论支撑。