"Sticky electrons" transport and interfacial transfer of electrons in the dye-sensitized solar cell.
"Sticky electrons" transport and interfacial transfer of electrons in the dye-sensitized solar cell.
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DOI：
10.1021/ar900143m
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发表时间：
2009-07
影响因子：
18.3
通讯作者：
L. Peter
中科院分区：
文献类型：
--
作者：
L. Peter
染料敏化太阳能电池（DSC，也称为Gratzel电池）通过使用敏化剂染料来收集光能以产生电力来模拟光合作用过程。这些光化学器件的几个功能特征是不寻常的，DSC研究提供了一个有价值的竞技场，在其中测试新的想法，新的材料，和新的方法。事实上，DSC最具吸引力的化学特性之一是其基本概念可用于构建一系列设备，用替代材料取代单个组件。然而，尽管二十年来研究活动不断增加，DSC中电子行为的许多方面仍然令人困惑。在这个帐户中，我们强调目前的理解的DSC的功能中所涉及的过程，特别强调在注射步骤后的中孔膜中的电子会发生什么。光注入电子的收集似乎涉及随机游走过程，其中电子移动通过互连的二氧化钛纳米颗粒的网络，同时经历频繁的捕获和脱陷。在它们传递到电池触点的过程中，电子可能通过转移到渗透中孔膜的氧化还原电解质中的三碘化物物质而损失。电子收集和反向电子转移之间的竞争决定了DSC的性能：理想情况下，所有注入的电子都应该被收集而没有损失。然后，该帐户继续调查该领域最近的实验和理论进展，特别强调在我们能够清楚地了解DSC如何工作之前需要解决的问题。关于“粘性”电子的行为的几个重要问题，那些经历多次捕获和脱陷，在DSC仍然没有答案。这些问题中最基本的是电子陷阱的性质，电子陷阱似乎主导了DSC的时间依赖性光电流和光电压响应。的强度和DSC光电压之间的关系的非理想因素的起源也是不清楚的，因为是由稳态和非稳态方法确定的电子扩散长度值的差异。有了这些未回答的问题，DSC研究很可能在未来几年内仍然是一个活跃和富有成果的领域。
Dye-sensitized solar cells (DSCs, also known as Gratzel cells) mimic the photosynthetic process by using a sensitizer dye to harvest light energy to generate electrical power. Several functional features of these photochemical devices are unusual, and DSC research offers a rewarding arena in which to test new ideas, new materials, and new methodologies. Indeed, one of the most attractive chemical features of the DSC is that the basic concept can be used to construct a range of devices, replacing individual components with alternative materials. Despite two decades of increasing research activity, however, many aspects of the behavior of electrons in the DSC remain puzzling. In this Account, we highlight current understanding of the processes involved in the functioning of the DSC, with particular emphasis on what happens to the electrons in the mesoporous film following the injection step. The collection of photoinjected electrons appears to involve a random walk process in which electrons move through the network of interconnected titanium dioxide nanoparticles while undergoing frequent trapping and detrapping. During their passage to the cell contact, electrons may be lost by transfer to tri-iodide species in the redox electrolyte that permeates the mesoporous film. Competition between electron collection and back electron transfer determines the performance of a DSC: ideally, all injected electrons should be collected without loss. This Account then goes on to survey recent experimental and theoretical progress in the field, placing particular emphasis on issues that need to be resolved before we can gain a clear picture of how the DSC works. Several important questions about the behavior of "sticky" electrons, those that undergo multiple trapping and detrapping, in the DSC remain unanswered. The most fundamental of these concerns is the nature of the electron traps that appear to dominate the time-dependent photocurrent and photovoltage response of DSCs. The origin of the nonideality factor in the relationship between the intensity and the DSC photovoltage is also unclear, as is the discrepancy in electron diffusion length values determined by steady-state and non-steady-state methods. With these unanswered questions, DSC research is likely to remain an active and fruitful area for some years to come.