Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility
Quantitative Study on β-Phase Heredity Based on Poly(9,9-dioctylfluorene) from Solutions to Films and the Effect on Hole Mobility
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基于聚(9,9-二辛基芴)从溶液到薄膜的β相遗传的定量研究及其对空穴迁移率的影响
DOI：
10.1021/acs.jpcc.6b08941
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发表时间：
2016-12-15
影响因子：
3.7
通讯作者：
Lu, Dan
中科院分区：
文献类型：
--
作者：
Bai, Zeming;Liu, Yang;Lu, Dan
本文研究了β相从溶液到基于聚（9，9-二辛基芴）（PFO）的薄膜的遗传性的定量关系、β相的形成机理以及β相含量对空穴迁移率的影响。通过紫外-可见吸收光谱表征了PFO从溶液到薄膜的遗传性。结果表明，在干燥成膜过程中，β相可以完全从溶液转移到膜中。PFO β相是稳定的，并且可以管理从液态到薄膜状态的动态变化。稀释溶液中β相含量较高，并通过动态光散射揭示了原因。因此，一个新的结构模型被构建，并呈现在PFO β相形成过程中不必要的聚合物链聚集。β相的能量状态低于α相。因此，PFO链自动组装成有序的。低浓度溶液的化学环境比高浓度溶液的化学环境更适宜。前者中的聚合物链可以比后者中的聚合物链更自由地适应平坦的几何形状，以促进链间堆叠。然后通过透射电子显微镜观察链聚集。还进行了具有线性增加电压的光诱导电荷提取，以检查PFO的电荷密度和空穴迁移率。当β相从0%增加到5.4%时，空穴迁移率可以提高一个数量级。因此，少量有序结构域的存在，可以形成互连的通道，可以大大提高材料的载流子传输在有序性差的有机薄膜，如PFO。这种条件可能对光电器件有利，而溶液中PFO链形成平坦几何形状的自适应性是促进系统有序性的主要因素。
In this work, the quantitative relationship in the heredity of beta-phase from a solution to a thin film based on poly(9,9-dioctylfluorene) (PFO), the mechanism of beta-phase formation, and the effects of beta-phase contents on hole mobility were investigated. The heredity based on PFO beta-phase from the solution to the thin film was characterized through UV-vis absorption. Results indicated that beta-phase can be completely transferred from solutions to films during drying to form films. PFO beta-phase was stable and could manage the dynamic changes from a liquid state to a thin-film state. The beta-phase content was higher in the diluted solutions, and the reason was revealed through dynamic light scattering. Thus, a new structure model was constructed, and polymer chain aggregation was rendered unnecessary during PFO beta-phase formation. The energy status of the beta-phase was lower than that of the a-phase. Consequently, PFO chains were autonomously assembled to become orderly. The chemical environment of the low-concentration solution was more suitable than that of the high-concentration solution. The polymer chains in the former could more freely adapt to a flat geometry than those in the latter to facilitate interchain stacking. Chain aggregation was then observed through transmission electron microscopy. Photoinduced charge extraction with a linear increase in voltage was also performed to examine the charge density and hole mobility of PFO. Hole mobility could be enhanced by an order of magnitude when beta-phase was increased from 0% to 5.4%. Thus, the presence of a small amount of ordered domains that can form interconnected channels could strongly enhance the carrier transport of materials in poorly ordered organic thin films, such as PFO. This condition is possibly beneficial for photoelectronic devices, and the adaptive nature of PFO chains in solutions to form a flat geometry is the main factor that promotes the order of the system.