Journal
MATERIALS HORIZONS
Volume 9, Issue 2, Pages 577-606Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/d0mh00837k
Keywords
-
Funding
- ONR [N000141712204, N000142012155]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]
- National Natural Science Foundation of China [52073207]
Ask authors/readers for more resources
The molecular ordering in semiconducting polymers plays a critical role in device performance. The article emphasizes the importance of quantifying molecular ordering and introduces consistent terminology for describing crystallinity, semi-crystallinity, and paracrystallinity. By combining X-ray scattering and calorimetry, a deeper understanding of molecular ordering can be achieved, leading to the classification of polymers based on quantitative analysis of disorder parameters and thermal transitions. Challenges in designing perfect polymer crystals are outlined, along with a proposed molecular grafting approach akin to epitaxy in classic semiconductor thin film growth.
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 (g) 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available