Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics
Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics
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DOI：
10.1038/ncomms1967
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发表时间：
2012-07-01
影响因子：
16.6
通讯作者：
Scherf, Ullrich
中科院分区：
文献类型：
--
作者：
Tautz, Raphael;Da Como, Enrico;Scherf, Ullrich
聚合物半导体是一种独特的光学和电子特性通常源自定制化学结构的材料。这使得可以合成具有有机电子学专用功能的共轭大分子。在光伏发电中，链上交替具有不同电子亲和力的部分的供体-受体共聚物引起了人们极大的兴趣。低带隙提供了最佳的光收集特性，并激发了人们朝着创纪录的功率转换效率的努力。在这里，我们首次展示了供体和受体部分的化学结构如何控制极化子对的光生成。我们发现，与均聚物 (eta=8%) 相比，具有强受体的共聚物显示出较高的极化子对形成产率，高达初始光激发的 24%。 π共轭间隔物将供体和受体的质量中心分开，具有增加重组时间的有益作用。这些结果为理解光伏低带隙共聚物中的极化子对光生作用提供了有用的信息。
Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donor-acceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (eta=8%). pi-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.