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White‐Light Emission from a Single Polymer with Singlet and Triplet Chromophores on the Backbone
Author(s) -
Zhen Hongyu,
Xu Wei,
Yang Wei,
Chen Qiliang,
Xu Yunhua,
Jiang Jiaxing,
Peng Junbiao,
Cao Yong
Publication year - 2006
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200600565
Subject(s) - polyfluorene , electroluminescence , pedot:pss , materials science , chromophore , polymer , singlet state , phosphorescence , light emission , photochemistry , oled , luminous efficacy , optoelectronics , fluorescence , chemistry , optics , nanotechnology , excited state , physics , composite material , atomic physics , layer (electronics)
Summary: A strategy to generate an efficient white‐light emission has been developed by mixing fluorescence and phosphorescence emission from a single polymer. Fluorene is used as the blue‐emissive component, benzothiadiazole (BT) and the iridium complex [(btp) 2 Ir(tmd)] are incorporated into a polyfluorene backbone, respectively, as green‐ and red‐emissive chromophores by Suzuki polycondensation. By changing the contents of BT and [(btp) 2 Ir(tmd)] in the polymer, the electroluminescence spectrum from a single polymer can be adjusted to achieve white‐light emission. A white polymeric light‐emitting diode (WPLED) with a structure of ITO/PEDOT:PSS/PVK/PFIrR1G03/CsF/Al shows a maximum external quantum efficiency of 3.7% and the maximum luminous efficiency of 3.9 cd · A −1 at the current density of 1.6 mA · cm −2 with the CIE coordinates of (0.33, 0.34). The maximum luminance of 4 180 cd · m −2 is achieved at the current density of 268 mA · cm −2 with the CIE coordinates of (0.31, 0.32). The white‐light emissions from such polymers are stable in the white‐light region at all applied voltages, and the electroluminescence efficiencies decline slightly with the increasing current density, thus indicating that the approach of incorporating singlet and triplet species into the polymer backbone is promising for WPLEDs.Structure of PFIrR1G04 and the EL spectra of its devices under various voltages. Device structure: ITO/PEDOT:PSS/PVK/polymer/CsF/Al.