Issue 29, 2007
From the journal:

Journal of Materials Chemistry

Luminescence of fluorenes 2,7-conjugatively extended with pyrenylvinylene and pyrenylvinylene-phenylenevinylene

Ali Cirpan,a   Hemali P. Rathnayake,b   Paul M. Lahti*b  and  Frank E. Karasz*a  

* Corresponding authors

a Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
E-mail: fekarasz@polysci.umass.edu
Fax: +1-413-253-5295
Tel: +1-413-545-4783

b Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
E-mail: lahti@chem.umass.edu
Fax: +1-413-253-5295
Tel: +1-413-545-4783

Abstract

2,7-Bis(1′-pyrenylvinylene)-9,9-diethylfluorene (1) and 2,7-bis(1′-pyrenylvinylene-4″-phenylenevinylene)-9,9-diethylfluorene (2) were synthesized and their static luminescence behavior assessed. They show solution photoluminescence (PL) maxima in chloroform at 475 nm and 467 nm, with quantum efficiencies of 54% and 52%, respectively. Double-layer LED devices with configuration ITO/PEDOT-PSS/(1 or 2)/Ca–Al emitted blue-green light with turn-on voltages of 2.5 V and emission maxima at 500 nm (2.48 eV); their luminance efficiencies were 0.36 and 0.30 cd A−1, respectively. Blending of 1 at 20% (w/w) in PVK improved the luminance efficiency to 1.81 cd A−1 for the same device configuration, with only a small increase in turn-on voltage to 3 V; the emission maximum was 497 nm (blue-green emission), the maximum luminance 7600 cd m−2 with CIE color coefficients of (0.12, 0.45). For a 10% (w/w) blend of 2 in PVK using the same device configuration, the luminance efficiency was 1.47 cd A−1, turn-on voltage 3 V, maximum luminance 2600 cd m−2 with CIE coefficients of (0.13, 0.45). Simple π-MO calculations show that structural extension of the nominal conjugation length in 2 does not significantly decrease the effective band gap relative to 1, consistent with the observed lack of red shift in 2.

Graphical abstract: Luminescence of fluorenes 2,7-conjugatively extended with pyrenylvinylene and pyrenylvinylene-phenylenevinylene

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Article information

DOI
https://doi.org/10.1039/B703180G
Article type
Paper
Submitted
06 Mar 2007
Accepted
26 Apr 2007
First published
18 May 2007

J. Mater. Chem., 2007,17, 3030-3036

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Luminescence of fluorenes 2,7-conjugatively extended with pyrenylvinylene and pyrenylvinylene-phenylenevinylene

A. Cirpan, H. P. Rathnayake, P. M. Lahti and F. E. Karasz, J. Mater. Chem., 2007, 17, 3030 DOI: 10.1039/B703180G

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