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White Electroluminescence from a Single‐Polymer System with Simultaneous Two‐Color Emission: Polyfluorene Blue Host and Side‐Chain‐Located Orange Dopant
Author(s) -
Liu J.,
Guo X.,
Bu L. J.,
Xie Z. Y.,
Cheng Y. X.,
Geng Y. H.,
Wang L. X.,
Jing X. B.,
Wang F. S.
Publication year - 2007
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200600988
Subject(s) - polyfluorene , materials science , electroluminescence , side chain , polymer , dopant , indium tin oxide , luminous efficacy , chromophore , photochemistry , polymer chemistry , optoelectronics , doping , thin film , nanotechnology , layer (electronics) , chemistry , composite material
Four single polymers with two kinds of attachment of orange chromophore to blue polymer host for white electroluminescence (EL) were designed. The effect of the side‐chain attachment and main‐chain attachment on the EL efficiencies of the resulting polymers was compared. The side‐chain‐type single polymers are found to exhibit more efficient white EL than that of the main‐chain‐type single polymers. Based on the side‐chain‐type white single polymer with 4‐(4‐alkyloxy‐phenyl)‐7‐(4‐diphenylamino‐phenyl)‐2,1,3‐benzothiadiazoles as the orange‐dopant unit and polyfluorene as the blue polymer host, white EL with simultaneous orange (λ max = 545 nm) and blue emission (λ max = 432 nm/460 nm) is realised. A single‐layer device (indium tin oxide/poly(3,4‐ethylenedioxythiophene)/polymer/Ca/Al) made of these polymers emits white light with the Commission Internationale de l'Éclairage coordinates of (0.30,0.40), possesses a turn‐on voltage of 3.5 V, luminous efficiency of 10.66 cd A –1 , power efficiency of 6.68 lm W –1 , and a maximum brightness of 21 240 cd m –2 .