LION, Huygens-Kamerlingh Onnes Laboratory, Leiden University , Niels Bohrweg 2, 2300RA Leiden, The Netherlands.
Chemical Physics and Nano Lund, Lund University , P.O. Box 124, 22100 Lund, Sweden.
Nano Lett. 2017 Mar 8;17(3):1575-1581. doi: 10.1021/acs.nanolett.6b04726. Epub 2017 Feb 27.
We simultaneously measured the absorption and emission of single conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) molecules in a poly(methyl methacrylate) (PMMA) matrix using near-critical xenon to enhance the photothermal contrast for direct absorption measurements. We directly measured the number of monomers and the quantum yield of single conjugated polymer molecules. Simultaneous absorption and emission measurements provided new insight into the photophysics of single conjugated polymers under optical excitation: quenching in larger molecules is more efficient than in smaller ones. Photoinduced traps and defects formed under prolonged illumination lead to decrease of both polymer fluorescence and absorption signals with the latter declining slower.
我们同时使用近临界氙气来增强光热对比度，以测量聚甲基丙烯酸甲酯（PMMA）基质中单个共轭聚合物聚[2-甲氧基-5-（2-乙基己氧基）-1,4-亚苯基乙烯基]（MEH-PPV）分子的吸收和发射。我们直接测量了单个共轭聚合物分子的单体数量和量子产率。同时进行吸收和发射测量为光学激发下单个共轭聚合物的光物理提供了新的见解：较大分子中的猝灭比较小分子中的更有效。在长时间光照下形成的光致陷阱和缺陷导致聚合物荧光和吸收信号都下降，而后者的下降速度较慢。
