Ter(9,9-diarylfluorene)s:  Highly Efficient Blue Emitter with Promising Electrochemical and Thermal Stability

• Published in: Journal of the American Chemical Society Vol. 124; no. 39; pp. 11576 - 11577
• Main Authors: Wong, Ken-Tsung, Chien, Yuh-Yih, Chen, Ruei-Tang, Wang, Chung-Feng, Lin, Yu-Ting, Chiang, Huo-Hsien, Hsieh, Ping-Yuan, Wu, Chung-Chih, Chou, Chung Hsien, Su, Yuhlong Oliver, Lee, Gene-Hsiang, Peng, Shie-Ming
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 02.10.2002; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Physical Sciences; Science & Technology; POLYFLUORENE DERIVATIVES; POLYMERS; DEVICES; POLYESTER; OLIGOMERS; SUBSTITUTED TERFLUORENE
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0269587

Novel ter(9,9-diarylfluorene)s were synthesized by a Suzuki-coupling reaction of 2-bromofluorene (1) and 2,7-fluorenediboronic ester derivatives (3) with high isolated yields (63−86%). The X-ray structure analysis of ter(9,9‘-spirobifluorene) (4aa) revealed that the conjugated chromophore adopts a helical conformation. This conformation effectively releases the steric interaction between the fluorene moieties and prevents inter-chromophore interactions. The introduction of aryl groups at the C9 position of fluorene was highly beneficial to the thermal and morphological stability of these oligomers. These terfluorenes exhibit intense blue fluorescence with excellent quantum yields both in solution (∼100%) and in solid state (66−90%), and possess interesting reversible redox properties. Highly efficient blue light-emitting OLED devices were fabricated using 4aa and 4 cc as emitters as well as hole transporters. The devices exhibit low turn-on voltage (∼3 V) and high EL external quantum efficiency (2.5−3%).