Competition between Host Aggregates and Isolated Guest Chromophores in Trapping Excitons in Polybenzazole Copolymers and Blends
✍ Scribed by Shanfeng Wang; Yan Chen; Qixin Zhuang; Xinxin Li; Pingping Wu; Zhewen Han
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 464 KB
- Volume
- 207
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
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.
magnified imageGeneral 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.