分子
光化学
芴
带隙
绿灯
荧光
电致发光
兴奋剂
半导体
二极管
量子纠缠
聚合物
材料科学
光电子学
化学
纳米技术
物理
有机化学
量子
光学
蓝光
量子力学
图层(电子)
作者
Bo Yang,Yuyu Liu,Hamid Soleimaninejad,Mengna Yu,Linghai Xie,Trevor A. Smith,Kenneth P. Ghiggino,Wei Huang
标识
DOI:10.1021/acs.jpca.9b00188
摘要
Blue-light-emitting semiconductors based on polyfluorenes often exhibit an undesired green emission band. In this report, three well-defined oligofluorenes corresponding to three types of “defects” attributed to aggregation, keto formation, and chain entanglement, respectively, are systemically investigated to unveil the origins of the green emission band in fluorene-based materials. First, the optical properties of defect molecules in different states are studied. The defect associated with aggregation is absent in dilute solutions and in films doped at 0.01 wt % with poly(methyl methacrylate). Second, the dependence of the emission spectra on the solvent was monitored to compare the effects of the “keto-” and “chain-entanglement defect” molecules. The green emission of keto defects exhibited a strong dependence on solvent polarity, whereas this cannot be observed in case of chain-entanglement defect. Third, energy transfer between poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenyl-fluoren-2,7-diyl] and the keto or chain-entanglement defect molecules is illustrated. Compared to those of the chain-entanglement defect, the spectra of the keto defect molecule (1:10–3) show signs of defect emission at lower proportions. These investigations not only provide insight into the photophysics of oligofluorenes but also supply a new strategy to explore defects in semiconductor polymers, which will aid in the development of effective approaches to obtain stable, pure blue organic light-emitting diodes based on polyfluorenes.
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