Fate of excitations in conjugated polymers: single-molecule spectroscopy reveals nonemissive "dark" regions in MEH-PPV individual chains.

Lin, Hongzhen; Tian, Yuxi; Zapadka, Karolina; Persson, Gustav; Thomsson, Daniel; Mirzov, Oleg; Larsson, Per-Olof; Widengren, Jerker et al. · Nano Lett · 2009

basic_science · Level V

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Abstract

Single chains of the conjugated polymer MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) were studied with wide-field fluorescence microscopy (dispersion in inert polymer matrices) and with fluorescence correlation spectroscopy (chloroform solution). The fluorescence yield of individual molecules in matrices was found to be 1-2 orders of magnitude lower than that in solution and it decreased substantially with increasing chain length. It suggests that isolation of MEH-PPV molecules in polymer matrices creates favorable conditions for photogeneration of nonemissive primary excited states.

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