Energy transfer dynamics in wire-type dendrimers having oligophenylene peripheries |
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Authors: | Ichiro Akai Masayuki Higuchi Katsuichi Kanemoto Tsutomu Karasawa Hideki Hashimoto Mutsumi Kimura |
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Institution: | 1. Shock Wave and Condensed Matter Research Center, Kumamoto University, Kumamoto 860-8555, Japan;2. Department of Physics, Osaka City University, Osaka 558-8585, Japan;3. Department of Functional Polymer Science, Shinshu University, Ueda 386-8567, Japan;1. Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid, Spain;2. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, 28049 Madrid, Spain;3. Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid, Spain |
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Abstract: | Energy transfer and shielding effect are studied in wire-type dendrimers (GnPPV: nth generation dendrimer with poly-(p-phenylenevinylene) backbone; n=1, 2) having oligophenylene light-harvesting (LH) antenna. Following the excitation of the LH-antennae, backbone-polymers in GnPPV give rise to intense photoluminescence (PL) bands. This is due to the presence of highly efficient energy transfer from the LH-antennae to the backbone-polymers. The intensity of backbone-PL increases faster than the decay of the antenna-PL. This result indicates that rapid energy transfer from antenna to backbone takes place utilizing the overlap of wavefunctions in the excited states. In G2PPV having larger LH-antenna, shielding effect against inter-backbone interactions is recognized more effectively than G1PPV. In solid films of GnPPV, red shifts of the backbone-PL bands are observed. This is caused by inter-backbone interactions of the wire-type dendrimers due to aggregation. The extent of the red shift in G2PPV is smaller than that of G1PPV. This result suggests that the larger LH-antenna in G2PPV substantially wraps its backbone-polymer and shields the inter-backbone interactions. |
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