Engineering Thin Films of a Tetrabenzoporphyrin toward Efficient Charge-Carrier Transport: Selective Formation of a Brickwork Motif
Engineering Thin Films of a Tetrabenzoporphyrin toward Efficient Charge-Carrier Transport: Selective Formation of a Brickwork Motif
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DOI：
10.1021/acsami.6b13988
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发表时间：
2017-03-08
影响因子：
9.5
通讯作者：
Yamada, Hiroko
中科院分区：
文献类型：
--
作者：
Takahashi, Kohtaro;Shan, Bowen;Yamada, Hiroko
四苯并卟啉（BP）是一种p型有机半导体，其特征在于具有大的刚性π框架、优异的稳定性以及良好的光吸收能力。这些特性使得BP及其衍生物成为有机电子和光电器件中突出的活性层组分。然而，对BP框架的固态排列的控制，特别是在溶液处理的薄膜中，尚未得到深入探究，并且与最佳有机分子半导体相比，在基于BP的材料中观察到的电荷载流子迁移率仍然相对较低。这项工作专注于对一种BP衍生物，即5,15 - 双（三异丙基硅基）乙炔基四苯并卟啉（TIPS - BP）的固态堆积进行工程设计，以实现其溶液处理薄膜中的高效电荷载流子传输。这种努力导致了一种砌砖式堆积的选择性形成，该堆积具有二维扩展的π - 堆积。所得薄膜中的最大场效应空穴迁移率达到1.1 cm² s⁻¹，这比原始的游离碱BP的记录值（0.070 cm² V⁻¹ s⁻¹）大约高14倍。这一成果主要通过对三个因素的优化实现；即沉积过程、浇铸溶剂以及构成介电表面的自组装单分子层。另一方面，偏振光显微镜和掠入射广角X射线衍射分析表明，分子排列的面内均匀性仍有一些改进空间，这表明通过进一步优化可以获得更高的电荷载流子迁移率。这些结果将为溶液处理的有机分子半导体中的多晶型工程和形态优化提供有用的基础。
Tetrabenzoporphyrin (BP) is a p-type organic semiconductor characterized by the large, rigid yr-framework, excellent stability, and good photoabsorption capability. These characteristics make BP and its derivatives prominent active layer components in organic electronic and optoelectronic devices. However, the control of the solid-state arrangement of BP frameworks, especially in solution-processed thin films, has not been intensively explored, and charge-carrier mobilities observed in BP-based materials have stayed relatively low as compared to those in the best organic molecular semiconductors. This work concentrates on engineering the solidstate packing of a BP derivative, 5,15-bis(triisopropylsilyl)ethynyltetrabenzoporphyrin (TIPS-BP), toward achieving efficient charge-carrier transport in its solution-processed thin films. The effort leads to the selective formation of a brickwork packing that has two dimensionally extended 7c-staking. The maximum field-effect hole mobility in the resulting films reaches 1.1 cm(2) s(-1), which is approximately 14 times higher than the record value for pristine free-base BP (0.070 cm(2) V-1 s(-1)). This achievement is enabled mainly through the optimization of three factors; namely, deposition process, cast solvent, and self-assembled monolayer that constitutes the dielectric surface. On the other hand, polarized-light microscopy and grazing-incident wide-angle X-ray diffraction analyses show that there remains some room for improvement in the in-plane homogeneity of molecular alignment, suggesting even higher charge-carrier mobilities can be obtained upon further optimization. These results will provide a useful basis for the polymorph engineering and morphology optimization in solution-processed organic molecular semiconductors.