Unification of trap-limited electron transport in semiconducting polymers
Unification of trap-limited electron transport in semiconducting polymers
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DOI：
10.1038/nmat3384
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发表时间：
2012-10-01
期刊：
影响因子：
41.2
通讯作者：
Blom, P. W. M.
中科院分区：
文献类型：
--
作者：
Nicolai, H. T.;Kuik, M.;Blom, P. W. M.
半导体聚合物中的电子传输通常不如空穴传输，空穴传输被归因于位于能隙内的孤立缺陷位上的电荷陷阱。然而，对这些无处不在的电荷陷阱的起源以及它们的能量位置、分布和集中缺乏普遍的了解。在这里，我们通过单载流子器件的电流-电压测量来研究广泛的半导体聚合物中的电子输运。我们观察到，对于这类材料，电子传输受到禁带中呈现高斯能量分布的陷阱的限制。值得注意的是，所研究的所有聚合物的电子陷阱分布都是相同的：陷阱数量达到每m(3)3×10(23)个陷阱，中心能量类似于真空度以下3.6 eV，典型分布宽度类似于0.1 eV。这表明电子陷阱有一个共同的起源，我们认为，很可能与水合氧络合物有关。这一发现的一个结果是，可以预测任何聚合物的陷阱限制电子电流。
Electron transport in semiconducting polymers is usually inferior to hole transport, which is ascribed to charge trapping on isolated defect sites situated within the energy bandgap. However, a general understanding of the origin of these omnipresent charge traps, as well as their energetic position, distribution and concentration, is lacking. Here we investigate electron transport in a wide range of semiconducting polymers by current-voltage measurements of single-carrier devices. We observe for this materials class that electron transport is limited by traps that exhibit a Gaussian energy distribution in the bandgap. Remarkably, the electron-trap distribution is identical for all polymers considered: the number of traps amounts to 3 x 10(23) traps per m(3) centred at an energy of similar to 3.6 eV below the vacuum level, with a typical distribution width of similar to 0.1 eV. This indicates that the electron traps have a common origin that, we suggest, is most likely related to hydrated oxygen complexes. A consequence of this finding is that the trap-limited electron current can be predicted for any polymer.