Increased efficient copolymers with PFV and PPDFV for light emitting diodes

New electroluminescent copolymers with fluoro groups in vinylene unit, poly(9,9-di-hexylfluorene-2, 7-vinylene-co-pphenylenedifluorovinylene) (PFVPDFV), have been synthesized by the GILCH polymerization. The fluoro groups were introduced on vinylene units to increase the electron affinities of the copolymers. The PFVPDFVs exhibit absorption spectra with maximum peaks at 371 ~ 413 nm. In the PL spectra of PFVPDFVs, as the PDFV content increases up to 50% in the copolymer system, fwhm was decreased by 4 - 38 nm as compared to PFV. The HOMO energy levels of the copolymers were about 5.25 - 5.50 eV, and the LUMO energy levels were about 2.67-2.97 eV. The polymer LEDs (ITO/PEDOT/polymer/Al) of PFVPDFVs showed emission with maximum peaks at around 472 - 538 nm. By adjusting the feed ratios of PDFV in the copolymers, it was possible to tune the emission colors from greenish yellow to orange depending on the obtained CIE coordinates. The luminescence efficiencies of the copolymers at room temperature are about 0.1-1.47 cd/A. The introduction of up to 50 % of PDFV in PFVPDFVS can enhance the device performance to result in high current density, brightness and efficiency due to the increased electron injection ability caused by the presence of fluoro groups in the vinylene units.

[1]  Arno Kraft,et al.  Electroluminescent Conjugated Polymers — Seeing Polymers in a New Light , 1998 .

[2]  Franco Cacialli,et al.  Novel poly(arylene vinylene)s carrying donor and acceptor substituents , 1996 .

[3]  Hong-Ku Shim,et al.  Green light-emitting diodes from poly(2-dimethyloctylsilyl-1,4-phenylenevinylene) , 1996 .

[4]  Jung-Il Jin,et al.  Synthesis and electrical properties of poly(2-bromo-5-methoxy-1,4-phenylenevinylene) and copolymers , 1992 .

[5]  Gerrit Klaerner,et al.  Oxidative Stability and Its Effect on the Photoluminescence of Poly(Fluorene) Derivatives: End Group Effects , 1999 .

[6]  F. E. Karasz,et al.  Red light emitting push-pull disubstituted poly(1,4-phenylenevinylenes) , 1996 .

[7]  R. H. Friend,et al.  Efficient light-emitting diodes based on polymers with high electron affinities , 1993, Nature.

[8]  Jinwoo Kim,et al.  Design, Synthesis, and Electroluminescent Property of CN-Poly(dihexylfluorenevinylene) for LEDs , 2003 .

[9]  Donal D. C. Bradley,et al.  Poly(p-phenylenevinylene) light-emitting diodes : enhanced electroluminescent efficiency through charge carrier confinement , 1992 .

[10]  Yongsup Park,et al.  Highly Efficient Light‐Emitting Diodes Based on an Organic‐Soluble Poly(p‐phenylenevinylene) Derivative Carrying the Electron‐Transporting PBD Moiety , 1998 .

[11]  Jean-Luc Brédas,et al.  Influence of donor and acceptor substituents on the electronic characteristics of poly(paraphenylene vinylene) and poly(paraphenylene) , 1994 .

[12]  Jin Young Kim,et al.  Poly(fluorenevinylene) Derivative by Gilch Polymerization for Light-Emitting Diode Applications , 2002 .

[13]  Donal D. C. Bradley,et al.  A New Electron-withdrawing Group Containing Poly(1,4-phenylenevinylene) , 1999 .

[14]  Chun Wang,et al.  Recent development of polyfluorene-based RGB materials for light emitting diodes , 2004, Microelectron. J..

[15]  R. N. Marks,et al.  Light-emitting diodes based on conjugated polymers , 1990, Nature.

[16]  Laurence Lutsen,et al.  The Gilch polymerisation towards OC1C10-PPV: indications for a radical mechanism , 2001 .

[17]  Ullrich Scherf,et al.  Semiconducting Polyfluorenes—Towards Reliable Structure–Property Relationships , 2002 .

[18]  Byung-Jun Jung,et al.  Synthesis and characterization of thermally stable blue light-emitting polyfluorenes containing siloxane bridges , 2003 .

[19]  F. E. Karasz,et al.  Polymerization of 1,4-bis(tetrahydrothiopheniomethyl)-2-cyano-5-methoxybenzene dibromide: synthesis of electronically ‘push-pull’ substituted poly(p-phenylene vinylene)s , 1994 .

[20]  Ullrich Mitschke,et al.  The electroluminescence of organic materials , 2000 .

[21]  Tetsuo Tsutsui,et al.  Sterically hindered fluorenyl-substituted poly(p-phenylenevinylenes) for light-emitting diodes , 2002 .

[22]  Shizuo Tokito,et al.  Highly efficient pure blue electroluminescence from polyfluorene: Influence of the molecular weight distribution on the aggregation tendency , 2000 .

[23]  A. Heeger,et al.  Flexible light-emitting diodes made from soluble conducting polymers , 1992, Nature.

[24]  Heinrich Becker,et al.  Soluble Phenyl‐Substituted PPVs—New Materials for Highly Efficient Polymer LEDs , 1998 .

[25]  Donal D. C. Bradley,et al.  High brightness and efficiency blue light-emitting polymer diodes , 1998 .

[26]  James J. O'Brien,et al.  Progress with Light‐Emitting Polymers , 2000 .

[27]  Heinrich Becker,et al.  New Insights into the Microstructure of GILCH-Polymerized PPVs , 1999 .

[28]  Abhishek P. Kulkarni,et al.  Blue light-emitting diodes with good spectral stability based on blends of poly(9,9-dioctylfluorene): Interplay between morphology, photophysics, and device performance , 2003 .

[29]  Jinwoo Kim,et al.  Novel electroluminescent polymers with fluoro groups in vinylene units , 2004 .

[30]  A. Heeger,et al.  Visible light emission from semiconducting polymer diodes , 1991 .

[31]  I. S. Millard,et al.  High-efficiency polyfluorene polymers suitable for RGB applications , 2000 .

[32]  Qibing Pei,et al.  Efficient blue electroluminescence from a fluorinated polyquinoline , 1994 .

[33]  Mats Andersson,et al.  Synthesis and Characterization of Highly Soluble Phenyl-Substituted Poly(p-phenylenevinylenes). , 2000 .

[34]  William R. Salaneck,et al.  Calcium electrodes in polymer LEDs , 1995 .

[35]  Abhishek P. Kulkarni,et al.  Electron Transport Materials for Organic Light-Emitting Diodes , 2004 .