White Polymer Light-Emitting Diodes Based on Star-Shaped Polymers with an Orange Dendritic Phosphorescent Core

• Published in: Macromolecular rapid communications. 2014-12, Vol.35 (24), p.2071-2076
• Main Authors: Zhu, Minrong, Li, Yanhu, Cao, Xiaosong, Jiang, Bei, Wu, Hongbin, Qin, Jingui, Cao, Yong, Yang, Chuluo
• Format: Article
• Language: English
• Subjects: Applied sciences; Backbone; Charge; Current efficiency; Dendrimers; Dendrimers - chemistry; Devices; Electronics; Exact sciences and technology; Fluorenes - chemistry; Light; Light-emitting diodes; Luminescence; Optoelectronic devices; Organic polymers; phosphorescent dendrimers; Physicochemistry of polymers; Polymers - chemical synthesis; Polymers - chemistry; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Spectrophotometry, Ultraviolet; star-shaped polymers; Trapping; White light; white polymer light-emitting diodes
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201400420

A series of new star‐shaped polymers with a triphenylamine‐based iridium(III) dendritic complex as the orange‐emitting core and poly(9,9‐dihexylfluorene) (PFH) chains as the blue‐emitting arms is developed towards white polymer light‐emitting diodes (WPLEDs). By fine‐tuning the content of the orange phosphor, partial energy transfer and charge trapping from the blue backbone to the orange core is realized to achieve white light emission. Single‐layer WPLEDs with the configuration of ITO (indium‐tin oxide)/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/polymer/CsF/Al exhibit a maximum current efficiency of 1.69 cd A−1 and CIE coordinates of (0.35, 0.33), which is very close to the pure white‐light point of (0.33, 0.33). To the best of our knowledge, this is the first report on star‐shaped white‐emitting single polymers that simultaneously consist of fluorescent and phosphorescent species. Star‐shaped single polymers with orange phosphorescent dendrimer as core and polyfluorene as arms are developed toward white polymer light‐emitting diodes (WPLEDs). The single‐layer white emissive device is realized with a current efficiency of 1.69 cd A−1, a maximum external quantum efficiency of 1.76%, and CIE coordinates of (0.35, 0.33).