Spectroscopic evidence for trap-dominated magnetic field effects in organic semiconductors
Spectroscopic evidence for trap-dominated magnetic field effects in organic semiconductors
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DOI：
10.1103/physrevb.90.155205
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
M. Cox;M. Wijnen;G. Wetzelaer;M. Kemerink;P. Blom;B. Koopmans
中科院分区：
文献类型：
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作者：
M. Cox;M. Wijnen;G. Wetzelaer;M. Kemerink;P. Blom;B. Koopmans
极化子陷阱在有机半导体中普遍存在，最近的证据表明它们可能是有机半导体中观测到的大磁场效应（MFE）的关键。在这里，我们测量MFE的聚合物薄膜器件与工程，辐射陷阱网站，以光谱调查的陷阱的影响。令人惊讶的是，在陷阱网站和聚合物骨架的发光被发现有一个相反的磁场响应。我们所有的结果是兼容的机制，其中自旋混合的陷阱可以创建大型MFE上观察到的骨干。这种情况下，定量证实了与磁场相关的激子密度在陷阱的数值漂移扩散模型。这些见解解决了研究领域内的一个突出争议。
Polaron traps are ubiquitous in organic semiconductors and recent evidence suggests they might be crucial for the large observed magnetic field effects (MFEs) in organic semiconductors. Here we measure MFEs in polymer thin-film devices with engineered, radiative trap sites in order to spectroscopically investigate the influence of the traps. Surprisingly, the luminescence at the trap sites and the polymer backbone is found to have an opposite response to a magnetic field. All our results are compatible with a mechanism in which spin mixing at the traps can create the large MFEs observed on the backbone. This scenario is quantitatively confirmed by numerical drift-diffusion modeling with magnetic-field-dependent exciton densities at the traps. These insights solve an outstanding controversy within the research field.