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Competition between Host Aggregates and Isolated Guest Chromophores in Trapping Excitons in Polybenzazole Copolymers and Blends
Author(s) -
Wang Shanfeng,
Chen Yan,
Zhuang Qixin,
Li Xinxin,
Wu Pingping,
Han Zhewen
Publication year - 2006
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200600469
Subject(s) - chromophore , exciton , excited state , photoluminescence , trapping , acceptor , materials science , ground state , copolymer , photochemistry , chemical physics , chemistry , polymer , optoelectronics , physics , atomic physics , condensed matter physics , ecology , composite material , biology
Abstract Summary: Host–guest systems have been prepared using the blends and copolymers consisting of the host molecule poly( p ‐phenylene benzobisoxazole) (PBO) with a higher bandgap of 2.93 eV and the guest molecule poly(2,5‐thienylbenzobisoxazole) (PBOT) with a lower bandgap of 2.57 eV. These systems have been investigated using photoluminescence (PL) spectra and time‐resolved PL decay dynamics. Both PBOT‐PBO copolymers and PBOT/PBO blends with the PBOT compositions less than 20% demonstrate higher intensities and narrower bandwidths in solid‐state emission compared to that of PBOT, as well as larger fractions of the shorter lifetime component in PL decay dynamics. A general scheme on intrachain and interchain exciton migration and trapping mechanism has been proposed to interpret the phenomena in both solutions and thin films. Particularly, a competition in trapping exciton between PBO aggregates and isolated PBOT chromophores has been revealed.General scheme of exciton migration and trapping paths for host (D: donor)–guest (A: acceptor) systems involving the isolated chromophores (A and D) and aggregates (AA and DD) in both ground state and excited state marked without or with an asterisk.