Intrinsic stretchable light-emitting conjugated polymers (LCPs) with low modulus play increasingly significant roles in flexible or skin-like displays. In this work, we focus on investigating the optoelectronic and mechanical properties of polyfluorene-based blue LCPs, of which the polymer side chains were straight alkyl chains (octyl) and branched alkyl chains (2-hexyldecyl). Comparatively, the solution-processed film of the polymer with branched alkyl chains exhibited substantially improved photoluminescence quantum yield (PLQY) from 18.9% to 46.5%. Benefiting from the internal plasticization of branched alkyl chains, the elastic modulus of polymer film reduced from 350 MPa to 180 MPa, confirming the validity of enhancing the alkyl/π ratio in lowering film stiffness and necessity for characterizing the intrinsic mechanical properties. Finally, polymer light-emitting diodes (PLED) that exhibited stable blue emission were achieved with the polyfluorene-based LCPs functionalized by branched alkyl chains. Overall, these observations manifest the feasibility of side-chain branching in tuning the mechanical properties of LCPs, and provide in-depth insights for developing intrinsic stretchable semiconductors.

中文翻译：

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具有低模量和更好的EL光谱稳定性的蓝光共轭聚合物


低模量的本征可拉伸发光共轭聚合物（LCP）在柔性或类皮肤显示器中发挥着越来越重要的作用。在这项工作中，我们重点研究聚芴基蓝色液晶聚合物的光电和机械性能，其聚合物侧链为直链烷基链（辛基）和支链烷基链（2-己基癸基）。相比之下，具有支化烷基链的聚合物的溶液加工膜的光致发光量子产率（PLQY）从18.9％显着提高到46.5％。受益于支化烷基链的内部增塑，聚合物薄膜的弹性模量从350 MPa降低至180 MPa，证实了提高烷基/π比在降低薄膜刚度方面的有效性以及表征固有机械性能的必要性。最后，利用支链烷基链功能化的聚芴基液晶聚合物实现了具有稳定蓝光发射的聚合物发光二极管（PLED）。总的来说，这些观察结果证明了侧链支化在调节 LCP 机械性能方面的可行性，并为开发本征可拉伸半导体提供了深入的见解。