Title: Bright-white light-emitting devices based on a single polymer exhibiting simultaneous blue, green, and red emissions
Authors: Chuang, Chu-Ying
Shih, Ping-I
Chien, Chen-Han
Wu, Fang-Iy
Shu, Ching-Fong
Department of Applied Chemistry
Issue Date: 23-Jan-2007
Abstract: We have developed efficient white-light-emitting polymers through the incorporation of low band gap green-light-emitting benzothiadiazole and red-light-emitting bisthiophenylbenzothiadiazole moieties into the backbone of a blue-light-emitting bipolar polyfluorene copolymer. Partial energy transfer from the blue-fluorescent polyfluorene backbone to the green- and red-fluorescent components resulted in individual emissions from the three emissive species. By carefully controlling the concentrations of the low-energy-emitting species in the resulting copolymers, the emission of white light, with contributions from each of the three primary colors, was achieved. Efficient polymer light-emitting devices prepared using these copolymers exhibited luminance efficiencies as high as 4.87 cd/A with color coordinates (0.37, 0.36) that were very close to the ideal CIE chromaticity coordinates for pure white light (0.33, 0.33). In addition, the color coordinates remained almost unchanged over a range of operating potentials. A mechanistic study suggested that energy transfer from the fluorene segments to the low band gap units, rather than charge trapping, was the main operating process involved in the electroluminescent process.
URI: http://dx.doi.org/10.1021/ma062192+
ISSN: 0024-9297
DOI: 10.1021/ma062192+
Volume: 40
Issue: 2
Begin Page: 247
End Page: 252
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