The recombination rates of two typical D–π–A dyes have been evaluated qualitatively by means of quantum chemical calculations. By dissecting the geometrical and electronic structures of the dyes, the function of the inserted phenyl ring in inhibiting recombination is recognized as the blocking of back electron transfer and decreasing the HOMO distribution on the anchoring group, but with the distorted structure caused by the inserted benzene ring also decreasing the light harvesting ability. Molecular designs for the screening of potential dyes are carried out with a comprehensive consideration of both suppressing recombination and enhancing light absorption. Tightening the adjacent rings in the donor and π-spacer is verified to be a feasible route for extending the π-conjugation, thus leading to red-shifted and broad absorption spectra. The calculated results show that the dyes possessing both a small distribution of the HOMO on the anchoring group and a relatively strong light harvesting ability are the most promising candidates for use in dye-sensitized solar cells. Moreover, this work provides a deep understanding of the relationship between the electron recombination rate and electronic structure of dyes, and provides theoretical guidelines for the design of high performance sensitizer materials.

中文翻译：

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用于抑制电子复合并增强用于敏化太阳能电池的染料的光吸收能力的分子设计：理论研究†

两种典型的D–π–A染料的重组率已通过量子化学计算进行了定性评估。通过解剖染料的几何和电子结构，插入的苯环在抑制重组中的功能被认为是阻断了反向电子传递并降低了锚固基团上的HOMO分布，但结构却因插入的苯引起环也降低了光收集能力。筛选潜在染料的分子设计在综合考虑抑制重组和增强光吸收的同时进行。证实将供体和π-间隔体中的相邻环拧紧是扩展π-共轭的可行途径，从而导致红移和宽吸收光谱。计算结果表明，既具有在锚固基团上的HOMO分布很小，又具有相对较强的光收集能力的染料是用于染料敏化太阳能电池的最有希望的候选者。此外，这项工作对染料的电子复合率与电子结构之间的关系有深入的了解，并为高性能敏化剂材料的设计提供了理论指导。