Crystallization-Arrested Viscoelastic Phase Separation in Semiconducting Polymer Gels
Crystallization-Arrested Viscoelastic Phase Separation in Semiconducting Polymer Gels
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DOI：
10.1021/acsapm.8b00195
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发表时间：
2018-11
影响因子：
5
通讯作者：
Jing He;Xiaoqing Kong;Yuhao Wang;Michael Delaney;D. Kalyon;Stephanie S. Lee
中科院分区：
文献类型：
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作者：
Jing He;Xiaoqing Kong;Yuhao Wang;Michael Delaney;D. Kalyon;Stephanie S. Lee
通过流变学表征和变温成像方法的结合，在半导体聚合物的稀溶液中发现了一种新的凝胶化途径，以实现具有分层孔隙度的相互连接的晶体网络。在快速冷却后，区域规则聚（3-己基噻吩）（rp - p3ht）在邻二氯苯中的溶液形成热可逆凝胶。变温共聚焦显微镜显示冷却诱导的结构重排通过粘弹性相分离进行。由于链内结晶，在RR-P3HT基体中形成微米级富溶剂“孔”时，相分离过程过早停止。低温扫描电镜结果显示，P3HT凝胶的纤维间网络具有纳米孔径。值得注意的是，当在溶液中加入第三种成分（小分子苯基C61丁酸甲酯（PCBM）或非结晶区随机(Rra)-P3HT）时，这些网络形成了相等的凝胶强度。用相分离溶液沉积活性层的有机太阳能电池的效率比对照电池高45%。
Through a combination of rheological characterization and temperature-variable imaging methods, a novel gelation pathway in dilute solutions of a semiconducting polymer to achieve interconnected, crystalline networks with hierarchical porosity is reported. Upon rapid cooling, solutions of regioregular poly(3-hexylthiophene) (RR-P3HT) in ortho-dichlorobenzene formed thermoreversible gels. Temperature-variable confocal microscopy revealed cooling-induced structural rearrangement to progress through viscoelastic phase separation. The phase separation process arrested prematurely during the formation of micron-sized solvent-rich "holes" within the RR-P3HT matrix due to intrachain crystallization. Cryogen-based scanning electron microscopy of RR P3HT gels revealed the existence of an interfibrillar network exhibiting nano-sized pores. Remarkably, these networks formed to equal gel strengths when a third component, either small molecule phenyl C61 butyric acid methyl ester (PCBM) or non-crystallizing regiorandom (Rra)-P3HT, was added to the solution. Organic solar cells in which the active layers were deposited from phase-separated solutions displayed 45% higher efficiency compared to reference cells.