Supermolecular control of charge transfer in dye-sensitized nanocrystalline TiO2 films:: Towards a quantitative structure-function relationship
Supermolecular control of charge transfer in dye-sensitized nanocrystalline TiO2 films:: Towards a quantitative structure-function relationship
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DOI：
10.1002/anie.200500363
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发表时间：
2005-01-01
影响因子：
16.6
通讯作者：
Durrant, JR
中科院分区：
文献类型：
--
作者：
Haque, SA;Handa, S;Durrant, JR
氧化还原或光敏分子与固体表面的附着对于许多应用的开发非常重要。目前受到广泛关注的一个研究领域是分子染料在介孔纳米晶金属氧化物电极上的固定化。这种功能化膜目前正在研究从太阳能电池到化学和生物传感器的器件应用。[1-6]最近，人们对使用更复杂的超分子或多功能敏化剂来构建包括杂超分子器件在内的一系列新应用产生了兴趣。[7-14]这种材料的使用特别有吸引力，因为它能够开发出表现出显著程度的结构组织、改善的稳定性、氧化还原可逆性和更大的功能多样性的电活性结构。[14-16]在电子器件中开发这种材料的关键要求是能够将超分子或多功能材料电连接到金属氧化物电极，同时实现对关键器件参数如界面电荷转移的控制。对于基于分子的吸附物，已经非常详细地考虑了这些问题，[17]但是对于包含更复杂的超分子或多功能敏化剂染料的功能化膜，还有待系统地解决。这种理解对于此类材料在电子器件中的设计和应用具有根本意义和必要性。在这里，我们解决这个问题，探索一类多功能敏化染料，表现出多步电荷转移级联。我们表明，通过精心设计的“supersensitivity”染料，它是可能的调制的电荷复合动力学的五个数量级，并实现显着长寿命的光致电荷分离在染料/二氧化钛界面。这些研究使我们能够解决超分子染料的结构和界面电荷转移之间的关系，并提供了一个洞察的基本过程，支配电荷转移动力学在超分子敏化剂染料/TiO 2 interfaces.We使用敏化剂染料，其中染料发色团被修改的二次电子供体的共价连接。如图1所示，通过在染料结构中引入这种二次电子转移级联，可以延迟电荷复合。
The attachment of redox or photoactive molecules to solid surfaces is important for the development of many applications. One area of research that is receiving extensive interest at present is the immobilization of molecular dyes on mesoporous nanocrystalline metal oxide electrodes. Such functionalized films are currently under investigation for device applications ranging from solar cells to chemical and biological sensors.[1–6] Recently there has been interest in the use of more complex supramolecular or multifunctional sensitizers to build a range of new applications including heterosupramolecular devices.[7–14] The use of such materials is particularly attractive as it enables the development of electroactive structures that exhibit a remarkable degree of structural organization, improved stability, redox reversibility, and a greater functional diversity.[14–16] A key requirement for the exploitation of such materials in electronic devices is the ability to electrically interface the supramolecular or multifunctional materials to the metal oxide electrode whilst achieving control over key device parameters such as interfacial charge transfer. Such issues have been considered in great detail for molecular-based adsorbates,[17] but are yet to be addressed systematically for functionalized films that comprise more complex, supramolecular or multifunctional sensitizer dyes. This understanding is both of fundamental interest and essential to the design and application of such materials in electronic devices. Herein we address this issue by exploring a class of multifunctional sensitizer dyes that exhibit multistep charge-transfer cascades. We show that by careful design of the “supersensitizer” dye it is possible to modulate the charge-recombination dynamics by five orders of magnitude and achieve remarkably long-lived photoinduced charge separation at a dye/TiO2 interface. These studies enable us to address the relationship between supermolecular dye structure and interfacial charge transfer and provide an insight into the fundamental processes that govern charge-transfer dynamics at the supermolecular sensitizer dye/TiO2 interface.We have used sensitizer dyes in which the dye chromophore is modified by the covalent attachment of secondary electron donors. By introducing such secondary electrontransfer cascades within the dye structure, as illustrated in Figure 1, it is possible to retard the charge-recombination