Utilization of water/alcohol-soluble polyelectrolyte as an electron injection layer for fabrication of high-efficiency multilayer saturated red-phosphorescence polymer light-emitting diodes by solution processing

Highly efficient multilayer red polymer light-emitting diodes were fabricated by solution process-ing from iridium complex, bis(1-(3-(9,9-dimethyl-fluorene-2-yl)phenyl)isoquinoline-C2,N′) iridium(III)acetylacetonate, doped into polyfluorene as a host and with a water/alcohol-soluble polymer, poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)propyl)-2,7-fluorene)-2,7-(9,9-dioctylfluorene)-4,7-(2,1,3-benzoselenadiazole)]dibromide (PFN) as electron injection layer. The device with the structure ITO∕PEDOT-PSS(50nm)∕PVK(40nm)∕PFO:PBD:Ir(DMFPQ)2acac(2%,75nm)∕PFN(20nm)∕Ba(4.5nm)∕Al(150nm) showed an external quantum efficiency of 18.0% and luminance efficiency of 9.8Cd∕A at a current density of 1.1mA∕cm2, a peak emission at λmax=636nm, and Commission International de I’Eclairage coordinates of (0.665, 0.319). The efficiency remained as high as QE=11.1%, and LE=6.0cd∕A, at a current density of 100mA∕cm2, and a luminance of 6140cd∕m2.

[1]  D. Moses,et al.  Water/Methanol‐Soluble Conjugated Copolymer as an Electron‐Transport Layer in Polymer Light‐Emitting Diodes , 2005 .

[2]  G. Malliaras,et al.  Photovoltaic measurement of the built-in potential in organic light emitting diodes and photodiodes , 1998 .

[3]  A. Jen,et al.  Highly efficient red electrophosphorescent devices based on an iridium complex with trifluoromethyl-substituted pyrimidine ligand , 2004 .

[4]  T. Sano,et al.  Fabrication process and device characteristics of multi-layered polymer light-emitting diodes , 2004 .

[5]  T. Wen,et al.  High efficiency red electrophosphorescent polymer light-emitting diode , 2006 .

[6]  Yong Cao,et al.  New iridium complex as high-efficiency red phosphorescent emitter in polymer light-emitting devices , 2006 .

[7]  M. Hashimoto,et al.  Substituent effects of iridium complexes for highly efficient red OLEDs. , 2005, Dalton transactions.

[8]  Efficient blue electroluminescent device using tetra(β-naphthyl)silane as a hole-blocking material , 2005 .

[9]  Hongbin Wu,et al.  Novel Electroluminescent Conjugated Polyelectrolytes Based on Polyfluorene , 2004 .

[10]  Yun Chi,et al.  Highly Efficient Electrophosphorescent Devices with Saturated Red Emission from a Neutral Osmium Complex , 2005 .

[11]  Dongge Ma,et al.  Highly efficient phosphorescent bis-cyclometalated iridium complexes based on quinoline ligands , 2005 .

[12]  Fei Huang,et al.  High-efficiency inverted top-emitting polymer light-emitting diodes , 2005 .

[13]  Effect of metal chelate layer on electroluminescent and current-voltage characteristics , 2005 .

[14]  Chin‐Ti Chen,et al.  Evolution of Red Organic Light-Emitting Diodes: Materials and Devices , 2004 .

[15]  Fei Huang,et al.  Efficient Electron Injection from a Bilayer Cathode Consisting of Aluminum and Alcohol‐/Water‐Soluble Conjugated Polymers , 2004 .

[16]  Jiaxing Jiang,et al.  Synthesis, photophysics, and electroluminescence of high-efficiency saturated red light-emitting polyfluorene-based polyelectrolytes and their neutral precursors , 2005 .

[17]  Hongbin Wu,et al.  High-efficiency, environment-friendly electroluminescent polymers with stable high work function metal as a cathode: green- and yellow-emitting conjugated polyfluorene polyelectrolytes and their neutral precursors. , 2004, Journal of the American Chemical Society.

[18]  Toshinao Yuki,et al.  Red‐phosphorescent OLEDs employing bis(8‐quinolinolato)phenolato‐aluminum(III) complexes as emission‐layer hosts , 2005 .

[19]  C. Shu,et al.  Tuning the emission and morphology of cyclometalated iridium complexes and their applications to organic light-emitting diodes , 2005 .

[20]  Franco Cacialli,et al.  LiF/Al cathodes and the effect of LiF thickness on the device characteristics and built-in potential of polymer light-emitting diodes , 2000 .

[21]  Junbiao Peng,et al.  High‐Efficiency, Saturated Red‐Phosphorescent Polymer Light‐Emitting Diodes Based on Conjugated and Non‐Conjugated Polymers Doped with an Ir Complex , 2004 .

[22]  F. Huang,et al.  Synthesis and optical and electroluminescent properties of novel conjugated polyelectrolytes and their neutral precursors derived from fluorene and benzoselenadiazole , 2006 .

[23]  Fei Huang,et al.  High-efficiency electron injection cathode of Au for polymer light-emitting devices , 2005 .

[24]  B. Tang,et al.  Polymer electrophosphorescent light-emitting diode using aluminum bis(2-methyl-8-quinolinato) 4-phenylphenolate as an electron-transport layer , 2004, IEEE Journal of Selected Topics in Quantum Electronics.