Hall Effect in Polycrystalline Organic Semiconductors: The Effect of Grain Boundaries
Hall Effect in Polycrystalline Organic Semiconductors: The Effect of Grain Boundaries
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DOI：
10.1002/adfm.201903617
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发表时间：
2019-07-11
影响因子：
19
通讯作者：
Podzorov, Vitaly
中科院分区：
文献类型：
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作者：
Choi, Hyun Ho;Paterson, Alexandra F.;Podzorov, Vitaly
有机半导体中的高结晶薄膜在高性能有机光电子学中具有重要的应用价值。本文研究了晶界对有机晶体管霍尔效应和电荷输运性能的影响，主要基于两种典型的基准体系：(1)溶液处理的2,7-二辛基[1]苯并噻吩[3,2-b][1]苯并噻吩（C-8-BTBT）小分子和吲哚二噻吩-苯并噻吩二唑（C16IDT-BT）共轭聚合物共混物，以及(2)大面积真空蒸发rubrene （C42H28）多晶薄膜。研究发现，尽管多晶有机晶体管具有高达6 cm(2) V-1 s（-1）的高场效应迁移率和离域类带电荷输运的证据，但由于载流子相干系数α < 1（即产生低估的霍尔迁移率和高估的载流子密度），霍尔效应在系统上明显不发达。描述了一个基于电容带电晶界的模型来解释这种不寻常的行为。这项工作极大地促进了对有机半导体薄膜磁输运特性的认识。
Highly crystalline thin films in organic semiconductors are important for applications in high-performance organic optoelectronics. Here, the effect of grain boundaries on the Hall effect and charge transport properties of organic transistors based on two exemplary benchmark systems is elucidated: (1) solution-processed blends of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C-8-BTBT) small molecule and indacenodithiophene-benzothiadiazole (C16IDT-BT) conjugated polymer, and (2) large-area vacuum evaporated polycrystalline thin films of rubrene (C42H28). It is discovered that, despite the high field-effect mobilities of up to 6 cm(2) V-1 s(-1) and the evidence of a delocalized band-like charge transport, the Hall effect in polycrystalline organic transistors is systematically and significantly underdeveloped, with the carrier coherence factor alpha < 1 (i.e., yields an underestimated Hall mobility and an overestimated carrier density). A model based on capacitively charged grain boundaries explaining this unusual behavior is described. This work significantly advances the understanding of magneto-transport properties of organic semiconductor thin films.