Role of Postdeposition Thermal Annealing on Intracrystallite and Intercrystallite Structuring and Charge Transport in Poly(3-hexylthiophene)
Role of Postdeposition Thermal Annealing on Intracrystallite and Intercrystallite Structuring and Charge Transport in Poly(3-hexylthiophene)
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DOI：
10.1021/acsami.0c16676
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发表时间：
2021-01-13
影响因子：
9.5
通讯作者：
Loo, Yueh-Lin
中科院分区：
文献类型：
--
作者：
Gu, Kaichen;Wang, Yucheng;Loo, Yueh-Lin
以共轭聚合物为有源层的电子器件的性能不仅取决于材料的本征特性，还取决于外在工艺条件的细节。在本研究中，我们研究了沉积后热处理对聚(3-己基噻吩基)(P3HT)薄膜微结构的影响及其对其电学性能的影响。不出所料，我们发现P3HT薄膜的热退火通常会增加其结晶度和微晶相干长度，同时保持相同的晶体结构。然而，尽管聚合物有源层的结构得到了如此有利的改善，但高温热退火会导致晶体管迁移率的净降低，这意味着这些半晶体有源层的晶间非晶区在退火时发生了结构变化，结晶度控制电荷传输的简单图景并不总是有效的。相反，我们的结果表明，在晶体生长和热处理后的完善过程中发生的结链拉出控制电荷传输，特别是在结链分数较低的低分子体系中。通过论证晶内和晶间结构在决定宏观电荷传输方面的相互作用，我们阐明了名义上相同的聚合物的结构演变和电荷传输性质如何随加工细节的不同而变化。
The performance of electronic devices comprising conjugated polymers as the active layer depends not only on the intrinsic characteristics of the materials but also on the details of the extrinsic processing conditions. In this study, we examine the effect of postdeposition thermal treatments on the microstructure of poly(3-hexylthiophene) (P3HT) thin films and its impact on their electrical properties. Unsurprisingly, we find thermal annealing of P3HT thin films to generally increase their crystallinity and crystallite coherence length while retaining the same crystal structure. Despite such favorable structural improvements of the polymer active layers, however, thermal annealing at high temperatures can lead to a net reduction in the mobility of transistors, implicating structural changes in the intercrystallite amorphous regions of these semicrystalline active layers take place on annealing, and the simplistic picture that crystallinity governs charge transport is not always valid. Our results instead suggest tie-chain pullout, which occurs during crystal growth and perfection upon thermal annealing to govern charge transport, particularly in low-molecular-weight systems in which the tie-chain fraction is low. By demonstrating the interplay between intracrystallite and intercrystallite structuring in determining the macroscopic charge transport, we shed light on how structural evolution and charge-transport properties of nominally the same polymer can vary depending on the details of processing.