Peng Zhengxing, Ye Long, Ade Harald
Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, North Carolina 27695, USA.
Mater Horiz. 2022 Feb 7;9(2):577-606. doi: 10.1039/d0mh00837k.
Molecular packing and texture of semiconducting polymers are often critical to the performance of devices using these materials. Although frameworks exist to quantify the ordering, interpretations are often just qualitative, resulting in imprecise use of terminology. Here, we reemphasize the significance of quantifying molecular ordering in terms of degree of crystallinity (volume fractions that are ordered) and quality of ordering and their relation to the size scale of an ordered region. We are motivated in part by our own imprecise and inconsistent use of terminology in the past, as well as the need to have a primer or tutorial reference to teach new group members. We strive to develop and use consistent terminology with regards to crystallinity, semicrystallinity, paracrystallinity, and related characteristics. To account for vastly different quality of ordering along different directions, we classify paracrystals into 2D and 3D paracrystals and use paracrystallite to describe the spatial extent of molecular ordering in 1-10 nm. We show that a deeper understanding of molecular ordering can be achieved by combining grazing-incidence wide-angle X-ray scattering and differential scanning calorimetry, even though not all aspects of these measurements are consistent, and some classification appears to be method dependent. We classify a broad range of representative polymers under common processing conditions into five categories based on the quantitative analysis of the paracrystalline disorder parameter () and thermal transitions. A small database is presented for 13 representative conjugated and insulating polymers ranging from amorphous to semi-paracrystalline. Finally, we outline the challenges to rationally design more perfect polymer crystals and propose a new molecular design approach that envisions conceptual molecular grafting that is akin to strained and unstrained hetero-epitaxy in classic (compound) semiconductors thin film growth.
半导体聚合物的分子堆积和织构通常对使用这些材料的器件性能至关重要。尽管存在用于量化有序性的框架，但解释往往只是定性的，导致术语使用不精确。在这里，我们再次强调根据结晶度（有序的体积分数）和有序质量及其与有序区域尺寸尺度的关系来量化分子有序性的重要性。部分原因是我们自己过去对术语的使用不精确且不一致，以及需要有一本入门指南或教程参考来教导新成员。我们努力在结晶度、半结晶度、准结晶度及相关特性方面开发和使用一致的术语。为了考虑沿不同方向的有序质量差异极大的情况，我们将准晶体分为二维和三维准晶体，并使用准晶微晶来描述1 - 10纳米范围内分子有序的空间范围。我们表明，通过结合掠入射广角X射线散射和差示扫描量热法，可以更深入地理解分子有序性，尽管这些测量的并非所有方面都是一致的，并且一些分类似乎取决于方法。基于对准晶无序参数（）和热转变的定量分析，我们将在常见加工条件下的一系列代表性聚合物分为五类。给出了一个包含13种从非晶到半准晶的代表性共轭和绝缘聚合物的小型数据库。最后，我们概述了合理设计更完美聚合物晶体的挑战，并提出了一种新的分子设计方法，该方法设想了类似于经典（化合物）半导体薄膜生长中的应变和非应变异质外延的概念性分子接枝。
