A Rational Molecular Design of β-Phase Polydiarylfluorenes: Synthesis, Morphology, and Organic Lasers

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• 作者：Jin-Yi Lin ; Wen-Sai Zhu ; Feng Liu ; Ling-Hai Xie ; Long Zhang ; Ruidong Xia ; Gui-Chuan Xing ; Wei Huang
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：February 11, 2014
• 年：2014
• 卷：47
• 期：3
• 页码：1001-1007
• 全文大小：431K
• ISSN：1520-5835

文摘

Rational molecular design allows for manipulating the chain conformations of polymer semiconductors by cooperative arrangement of bulky groups with steric hindrance effect and supramolecular groups with noncovalent attractions. Herein, a model polyfluorene with 尾-phase, poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenylfluoren-2,7-diyl] (PODPF), has been synthesized successfully via key Baeyer鈥揤illiger rearrangement reaction. Its thin film exhibited excellent spectral stability without green band emission after thermal annealing at 200 掳C under air and nitrogen ambients. The 尾-phases of PODPF in the concentrated toluene solution, organogels, and films have been characterized and confirmed by UV absorption and PL spectra as well as grazing-incidence X-ray scattering. The results suggest that the octyloxy substituents enable backbone planarization via van der Waals forces of the in-plane alkyl chains to overcome intrachain repulsion between fluorene monomers. Organic lasers using 尾-phase PODPF exhibit lower threshold than those of poly(9,9-dioctylfluorene), suggesting promising optical gain media. This observation suggested that supramolecular steric hindrance (SSH) is a promising molecular design of polymer semiconductors, and supramolecular steric polymers are one kind of model to get insight into the structure鈥揻unction relationships for electrically pumped organic lasers in organic electronic and photonics.