Bright-White Light-Emitting Devices Based on a Single Polymer Exhibiting Simultaneous Blue, Green, and Red Emissions

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• 作者：Chu-Ying Chuang ; Ping-I Shih ; Chen-Han Chien ; Fang-Iy Wu ; Ching-Fong Shu
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：January 23, 2007
• 年：2007
• 卷：40
• 期：2
• 页码：247 - 252
• 全文大小：118K
• 年卷期：v.40,no.2(January 23, 2007)
• ISSN：1520-5835

文摘

We have developed efficient white-light-emitting polymers through the incorporation of low bandgap green-light-emitting benzothiadiazole and red-light-emitting bisthiophenylbenzothiadiazole moieties into thebackbone of a blue-light-emitting bipolar polyfluorene copolymer. Partial energy transfer from the blue-fluorescentpolyfluorene backbone to the green- and red-fluorescent components resulted in individual emissions from thethree emissive species. By carefully controlling the concentrations of the low-energy-emitting species in theresulting copolymers, the emission of white light, with contributions from each of the three primary colors, wasachieved. Efficient polymer light-emitting devices prepared using these copolymers exhibited luminance efficienciesas high as 4.87 cd/A with color coordinates (0.37, 0.36) that were very close to the ideal CIE chromaticitycoordinates for pure white light (0.33, 0.33). In addition, the color coordinates remained almost unchanged overa range of operating potentials. A mechanistic study suggested that energy transfer from the fluorene segmentsto the low band gap units, rather than charge trapping, was the main operating process involved in theelectroluminescent process.