Manipulating Conjugated Polymer Backbone Dynamics through Controlled Thermal Cleavage of Alkyl Side Chains
Manipulating Conjugated Polymer Backbone Dynamics through Controlled Thermal Cleavage of Alkyl Side Chains
复制标题
通过烷基侧链的受控热裂解控制共轭聚合物主链动力学
DOI：
10.1002/marc.202200533
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发表时间：
2022
影响因子：
4.6
通讯作者：
You, Wei
中科院分区：
文献类型：
--
作者：
Zhao, Haoyu;Shanahan, Jordan J.;Samson, Stephanie;Li, Zhaofan;Ma, Guorong;Prine, Nathaniel;Galuska, Luke;Wang, Yunfei;Xia, Wenjie;You, Wei
有机光伏（OPV）器件的形态稳定性受到器件工作温度附近发生的施主和受主动力学的极大影响。这些动力学可以通过共轭聚合物（CP）的玻璃化转变温度（Tg）来量化。由于柔性侧链具有快得多的动力学，烷基侧链的裂解将降低链动力学，导致更高的Tg。在本工作中，系统地研究了控制侧链断裂的CP的Tg。发现在140 °C下等温退火具有热可裂解侧链的聚噻吩在24小时内去除95%以上的烷基侧链，并将主链Tg从23 ° C提高到75 °C。粗粒分子动力学模拟用于了解Tg对侧链裂解的依赖性。X射线散射表明，在等温退火过程中，相对结晶度保持不变。有效共轭长度不受热裂解的影响;然而，在完全去除烷基侧链后，发色团的密度加倍。在热裂解过程中提高Tg和保持晶体结构的组合效应可以提供一种改善未来OPV器件光电性能稳定性的途径。
The morphological stability of an organic photovoltaic (OPV) device is greatly affected by the dynamics of donors and acceptors occurring near the device's operational temperature. These dynamics can be quantified by the glass transition temperature (Tg) of conjugated polymers (CPs). Because flexible side chains possess much faster dynamics, the cleavage of the alkyl side chains will reduce chain dynamics, leading to a higherTg. In this work, theTgs for CPs are systematically studied with controlled side chain cleavage. Isothermal annealing of polythiophenes featuring thermally cleavable side chains at 140 °C, is found to remove more than 95% of alkyl side chains in 24 h, and raise the backboneTgfrom 23 to 75 °C. Coarse grain molecular dynamics simulations are used to understand theTgdependence on side chain cleavage. X‐ray scattering indicates that the relative degree of crystallization remains constantduring isothermal annealing process. The effective conjugation length is not influenced by thermal cleavage; however, the density of chromophore is doubled after the complete removal of alkyl side chains. The combined effect of enhancingTgand conserving crystalline structures during the thermal cleavage process can provide a pathway to improving the stability of optoelectronic properties in future OPV devices.