Gu Kaichen, Snyder Chad R, Onorato Jonathan, Luscombe Christine K, Bosse August W, Loo Yueh-Lin
Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States.
Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.
ACS Macro Lett. 2018 Nov 20;7(11):1333-1338. doi: 10.1021/acsmacrolett.8b00626. Epub 2018 Nov 1.
Intercrystallite molecular connections are widely recognized to tremendously impact the macroscopic properties of semicrystalline polymers. Because it is challenging to directly probe such connections, theoretical frameworks have been developed to quantify their concentrations and predict the mechanical properties that result from these connections. Tie-chain connectivity similarly impacts the electrical properties in semicrystalline conjugated polymers. Yet, its quantitative impact has eluded the community. Here, we assess the Huang-Brown model, a framework commonly used to describe the structural origins of mechanical properties in polyolefins, to quantitatively elucidate the effect of tie chains on the electrical properties of a model conjugated polymer. We found that a critical tie-chain fraction of 10 is needed to support macroscopic charge transport, below which intercrystallite connectivity limits charge transport, and above which intracrystallite disorder is the bottleneck. Extending the Huang-Brown framework to conjugated polymers enables the prediction of macroscopic electrical properties based on experimentally accessible morphological parameters. Our study implicates the importance of long and rigid polymer chains for efficient charge transport over device length scales.
人们普遍认为，微晶间分子连接对半结晶聚合物的宏观性能有巨大影响。由于直接探测这种连接具有挑战性，因此已经开发了理论框架来量化它们的浓度，并预测由这些连接产生的机械性能。连接链的连通性同样会影响半结晶共轭聚合物的电学性能。然而，其定量影响尚未得到该领域的明确认识。在这里，我们评估了黄-布朗模型（一种常用于描述聚烯烃机械性能结构起源的框架），以定量阐明连接链对一种模型共轭聚合物电学性能的影响。我们发现，需要10%的临界连接链分数来支持宏观电荷传输，低于该分数时，微晶间连通性限制电荷传输，高于该分数时，晶内无序成为瓶颈。将黄-布朗框架扩展到共轭聚合物能够基于实验可获取的形态参数预测宏观电学性能。我们的研究表明，长而刚性的聚合物链对于在器件长度尺度上实现高效电荷传输至关重要。
