Green polymer-light-emitting-diodes based on polyfluorenes containing N-aryl-1,8-naphthalimide and 1,8-naphthoilene-arylimidazole derivatives as color tuner
✍ Scribed by Jung-Feng Lee; Steve Lien-Chung Hsu
- Book ID
- 104088067
- Publisher
- Elsevier Science
- Year
- 2009
- Tongue
- English
- Weight
- 498 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0032-3861
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✦ Synopsis
A novel series of green light emitting single polymers were prepared by end-capping of N-aryl-1,8-naphthalimide and 1,8-naphthoilenearylimidazole derivatives into polyfluorene. The electroluminescence (EL) spectra of polymers (P1 w P5) exhibit greenish-blue, bluish-green, pure green, and yellowish-green emission (l max ¼ 465 nm, 490 nm, 500 nm, and 545 nm, respectively) from compounds (M1 w M5). It was found that by the introduction of a small amount of compounds (M1 w M5) (5 mol-%) into polyfluorene, the emission color can be tuned from the blue to green region. The color tuning was found to have gone through charge trapping and Fo ¨rster energy transfer. The device of P4 emits pure green light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.20, 0.41), and exhibits a maximum brightness of 11500 cd/m 2 at 12 V with a structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) [PEDOT:PSS]/PVK/emission layer/Ca/Ag. The device of P5 emits yellowish green light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.36, 0.56), and exhibits a maximum brightness of 6534 cd/m 2 at 17 V.