title: Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs.
abstract: By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene) (PFO), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed. The insertion of the NSI unit into the PFO backbone leads to the increase of local effective conjugation length, to form low-energy fluorene-NSI-fluorene (FNF) segments that serve as exciton trapping sites, to which the energy transfers from the high-energy PFO segments. This causes these copolymers to show red-shifted emissions compared with PFO, with a high efficiency and good color stability and purity. The best device performance with a luminance efficiency of 3.43 cd · A(-1) , a maximum brightness of 6 539 cd · m(-2) , and CIE coordinates of (0.152, 0.164) was achieved.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China; Graduate School of Chinese Academy of Sciences, Beijing 100039, P. R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Cheng
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Xie
authors.forename: Yanhou
authors.initials: Y
authors.lastname: Geng
authors.forename: Lixiang
authors.initials: L
authors.lastname: Wang
authors.forename: Xiabin
authors.initials: X
authors.lastname: Jing
authors.forename: Fosong
authors.initials: F
authors.lastname: Wang