Study of local structure at crystalline rubrene grain boundaries via scanning transmission X-ray microscopy
Study of local structure at crystalline rubrene grain boundaries via scanning transmission X-ray microscopy
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DOI：
10.1016/j.orgel.2019.07.021
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发表时间：
2019-11
影响因子：
3.2
通讯作者：
A. Foggiatto;Y. Takeichi;K. Ono;H. Suga;Y. Takahashi;Michael A. Fusella;Jordan T. Dull;Barry P Rand;K. Kutsukake;T. Sakurai
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文献类型：
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作者：
A. Foggiatto;Y. Takeichi;K. Ono;H. Suga;Y. Takahashi;Michael A. Fusella;Jordan T. Dull;Barry P Rand;K. Kutsukake;T. Sakurai
红荧烯是一种很有前途的有机半导体材料，具有很高的空穴迁移率。然而，这种高迁移率仅存在于其结晶状态，在无序薄膜中数量级减少。因此，由于它属于薄膜多晶红荧烯，重要的是要了解结构和无序区域的存在下，在晶界。在这里，我们使用扫描透射X射线显微镜（STXM）来研究多晶红荧烯薄膜与血小板或球晶形态。STXM图像使我们能够区分和量化晶体中局部结构的排列。分析表明，片晶膜中的取向分子比球晶相中的取向分子多。此外，在球晶晶界处，我们揭示了与片状情况下的光滑边界相比大量的未对准分子，片状和球晶情况下的晶界弯曲度分别为0.045 ± 0.002和0.139 ± 0.002μm，这有助于解释前一种情况下的较高流动性。
Rubrene is a promising and archetypal organic semiconductor owing to its high reported hole mobility. However, this high mobility only exists in its crystalline state, with orders of magnitude reduction in disordered films. Thus, as it pertains to thin film polycrystalline rubrene, it is important to understand structure and the presence of disordered regions at grain boundaries. Here, we use scanning transmission X-ray microscopy (STXM) to investigate polycrystalline rubrene thin films with either platelet or spherulite morphology. The STXM images allow us to distinguish and quantify the arrangement of the local structure in the crystal. The analysis suggests that the platelet film has more oriented molecules in the crystal than in the spherulite phase. Also, at spherulite grain boundaries, we reveal a high number of misaligned molecules compared to the smooth boundary in the platelet case, with grain boundary sinuosity of 0.045 ± 0.002 and 0.139 ± 0.002μm for the platelet and spherulite cases, respectively, which help to explain the higher mobility in the former case.