Excimer and Exciton Fusion of Blends and Molecularly Doped Polymers--A New Morphological Tool.

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Abstract

Exciton-exciton and exciton-excimer triplet fusion kinetics is monitored in medium molecular weight P1VN/PMMA solvent cast films with concentrations from 0.005 to 100% (weight), at temperatures of 77 to 300 K, via time resolved fluorescence and phosphorescence (10 ns to 10 sec). The heterogeneity exponent (h) is 0.5 for isolated P1VN chains, zero (classical) for pure P1VN and “fractal-like” throughout certain concentration regimes. However, h is not monotonic with blend concentration but rather oscillates between zero and 0.5. Correlation is made with morphology changes (phase separation, filamentation). As expected, the triplet exciton kinetics is dominated by short-range hops (about 5 A) and thus monitors the primary topology of the chains. At concentrations below 0.01%, the excitons are constrained to a truly one-dimensional topology. At higher concentrations there is a fractal-like topology. Similar studies were conducted on naphthalene-doped PMMA (1-20% weight). The lower concentration samples are neither segregated nor random solution phases.

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Correspondence to Zhong-You Shi.

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Shi, ZY., Li, CS. & Kopelman, R. Excimer and Exciton Fusion of Blends and Molecularly Doped Polymers--A New Morphological Tool.. MRS Online Proceedings Library 171, 245–254 (1989). https://doi.org/10.1557/PROC-171-245

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