Comparison of the Mechanical Properties of a Conjugated Polymer Deposited Using Spin Coating, Interfacial Spreading, Solution Shearing, and Spray Coating
Comparison of the Mechanical Properties of a Conjugated Polymer Deposited Using Spin Coating, Interfacial Spreading, Solution Shearing, and Spray Coating
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DOI：
10.1021/acsami.1c13043
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发表时间：
2021-10-22
影响因子：
9.5
通讯作者：
Lipomi, Darren J.
中科院分区：
文献类型：
--
作者：
Choudhary, Kartik;Chen, Alexander X.;Lipomi, Darren J.
π-共轭（半导体）聚合物的机械性能是设想用于能源和医疗保健应用的器件的稳定性和可制造性的关键决定因素。这些性能，包括模量，延展性，韧性和强度，是由固体膜的形态，这取决于加工方法的影响。迄今为止，大多数关于半导体聚合物的机械性能的工作都是在通过旋涂沉积的薄膜上进行的，这是一种不适合制造大面积薄膜的工艺。在这里，我们比较的机械性能的区域规则的聚（3-庚基噻吩）（P3 HpT）薄膜生产的三个可扩展的沉积过程-界面扩展，溶液剪切，喷涂和旋涂（作为参考）。我们的研究结果导致四个主要结论。(1)喷涂膜由于缺陷和不均匀的厚度而具有差的机械鲁棒性。(2)剪切膜显示出最高的模量、强度和韧性，这可能是由于自由体积的减少。(3)界面扩展膜显示出较低的模量，但更大的断裂应变比旋涂膜。(4)在使用不同沉积工艺浇铸的膜的拉伸行为中观察到的趋势对于P3 HpT和聚（3-丁基噻吩）（P3 BT）（具有较高玻璃化转变温度的类似物）两者都成立。掠入射X射线衍射和紫外-可见光谱揭示了许多显着的差异，在固体结构的P3 HpT薄膜产生的所有四个过程。虽然这些形态的差异提供了可能的解释，在电子特性（空穴迁移率）的差异，我们发现，薄膜的机械性能的自由体积和表面形貌为主。在场效应晶体管中，铺展膜的迁移率比任何其他膜都大1个数量级以上，这可能是由于结晶域中相对高比例的边缘纹理和长相干长度。总的来说，铺展膜提供了变形性和电荷传输特性的最佳组合。
The mechanical properties of pi-conjugated (semiconducting) polymers are a key determinant of the stability and manufacturability of devices envisioned for applications in energy and healthcare. These properties-including modulus, extensibility, toughness, and strength-are influenced by the morphology of the solid film, which depends on the method of processing. To date, the majority of work done on the mechanical properties of semiconducting polymers has been performed on films deposited by spin coating, a process not amenable to the manufacturing of large-area films. Here, we compare the mechanical properties of thin films of regioregular poly(3-heptylthiophene) (P3HpT) produced by three scalable deposition processes-interfacial spreading, solution shearing, and spray coating-and spin coating (as a reference). Our results lead to four principal conclusions. (1) Spray-coated films have poor mechanical robustness due to defects and inhomogeneous thickness. (2) Sheared films show the highest modulus, strength, and toughness, likely resulting from a decrease in free volume. (3) Interfacially spread films show a lower modulus but greater fracture strain than spin-coated films. (4) The trends observed in the tensile behavior of films cast using different deposition processes held true for both P3HpT and poly(3-butylthiophene) (P3BT), an analogue with a higher glass transition temperature. Grazing incidence X-ray diffraction and ultraviolet-visible spectroscopy reveal many notable differences in the solid structures of P3HpT films generated by all four processes. While these morphological differences provide possible explanations for differences in the electronic properties (hole mobility), we find that the mechanical properties of the film are dominated by the free volume and surface topography. In field-effect transistors, spread films had mobilities more than 1 magnitude greater than any other films, likely due to a relatively high proportion of edge-on texturing and long coherence length in the crystalline domains. Overall, spread films offer the best combination of deformability and charge-transport properties.