Relaxation dynamics of 2,7- And 3,6-distyrylcarbazoles in solutions and in solid films: Mechanism for efficient nonradiative deactivation in the 3, 6-linked carbazole

Tsai Te Wang, Szu Min Chung, Fang Iy Wu, Ching Fong Shu, Wei-Guang Diau*

*Corresponding author for this work

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

We performed time-resolved spectral investigations of two distyrylcarbazole derivatives, 2,7- and 3,6-distyrylcarbazole (2,7-DPVTCz and 3,6-DPVTCz, respectively), in dilute toluene solution and in solid films mixed with poly(methyl methacrylate) (PMMA). The lifetime of 2,7-DPVTCz in its excited state in solution is ~100 times as great as that of 3,6-DPVTCz, consistent with their photophysical nature. The former shows intense emission, but the latter is nearly nonfluorescent in a free environment. Moreover, the lifetime of 3,6-DPVTCz in its excited state increased also ~100 times when the molecule was encapsulated in a 3,6-DPVTCz/PMMA solid film, indicating that intramolecular motion of the molecule significantly affects the observed relaxation dynamics in a confined environment. Calculations on the excited states indicate that an efficient intersystem crossing is activated upon twisting of the bridged C-C single bond in a free 3,6-linked carbazole; such efficient deactivation is impractical in 2,7-linked carbazole or for 3,6-linked carbazole in a PMMA matrix. Information obtained from experiments on femtosecond fluorescence enables us to distinguish crucial relaxation processes in the excited state for a profound understanding of the details of vibrational and electronic relaxations of 3,6-DPVTCz in solution.

Original languageEnglish
Pages (from-to)23827-23835
Number of pages9
JournalJournal of Physical Chemistry B
Volume109
Issue number50
DOIs
StatePublished - 22 Dec 2005

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