Blue light-emitting hyperbranched polymers used fluorene-co-dibenzothiophene-S,S-dioxide as branch Ting Guo, Lei Yu, Lei Ying, Wei Yang, Yong Cao State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, China 510640，pswyang@scut.edu.cn
ABSTRACT
Polymer light-emitting diodes (PLEDs) have gained tremendous attention due to their broad application prospects in full-color flat-panel electroluminescence (EL) displays, and next-generation solid-state lighting sources[1]. Among the currently available conjugated polymers as the emissive layer for PLEDs, blue light-emitting polymers remain a great challenge in terms of luminous efficiency and spectra stability with respect to the green and red light-emitting counterparts[2-4]. We present current progress on the realization of blue-emitting polyfluorenes with high efficiency used fluorene-co-dibenzothiophene-S,S-dioxide as the branch and triazine, benzene or triphenylamine as the core,respectively. All resulted hyperbranched polymers exhibited quite comparable thermal properties with the glass transition temperatures in the range of 59–68 oC and relatively high decomposition temperatures over 420 oC. Polymer light-emitting devices demonstrated blue emission with excellent stability of electroluminescence. Copolymers based on smaller core units of benzene and triphenylamine exhibited superior performances to triphenyltriazine. With the configuration of ITO/PEDOT:PSS/polymer/CsF/Al, a maximum luminous efficiency of 4.5cd/A with a corresponding external quantum efficiency of 2.7% was obtained with CIE coordinates of (0.16, 0.19) for the polymer PFSO15B. These results indicate that hyperbranched structure is very promising to obtain spectrally stable blue-light-emitting polymers with high efficiency. Acknowledgements This work was financially supported by the National Nature Science Foundation of China (No. 21074038) and the State Key Basic Research Project of China (No.2009CB623600).
References
1. H. B. Wu, L. Ying, W. Yang, Y. Cao, Chem. Soc. Rev. 38, 3391( 2009).
2. J. Liu, J. H. Zou, W. Yang, H. B. Wu, C. Liu, Y. Cao, Chem. Mater. 20, 4499 (2008).
3. H. P. Xiao, L. Yu, Y. H. Li, B. Zhang, W. Yang, Y. Cao, Polymer 53, 2873 (2012).
4. L. Yu, J. Liu, S. J. Hu, R. F. He, W. Yang, H. B. Wu, J. B. Peng, R. D. Xia and D. D. C. Bradley, Adv. Funct. Mater. 23, 4366 (2013).