Indium-tin oxide treatments for single- and double-layer polymeric light-emitting diodes: The relation between the anode physical, chemical, and morphological properties and the device performance

We report combined studies of the influence of chemical and physical treatments on the properties of indium–tin oxide (ITO) thin films. The ITO films were also used as transparent anodes of polymeric light-emitting diodes (LEDs) incorporating poly(p-phenylene vinylene) (PPV) as the emitter material, with, or without, doped poly(3,4-ethylene dioxythiophene) (PEDOT) as a hole-injection/transport layer. Structures based on a soluble green derivative of PPV, poly(4,4′-diphenylene diphenylvinylene) were also tested. We studied chemical (aquaregia, degreasing, RCA protocol) and physical (oxygen and argon plasmas, Teflon, and paper rubbing) treatments and, in contrast to recently published work, we find that for Balzer Baltracon ITO, oxygen plasma and not aquaregia yields the highest efficiencies and luminances and the lowest drive voltages. For oxygen-plasma-treated anodes, the device efficiency clearly correlates with the value of the ITO surface work function, which in turn depends on the time of treatment. I...

[1]  Hany Aziz,et al.  A degradation mechanism of organic light-emitting devices , 1996 .

[2]  J. C. Scott,et al.  Enhanced luminance in polymer composite light emitting devices , 1997 .

[3]  Klavs F. Jensen,et al.  Photo-oxidation of polymers used in electroluminescent devices , 1995 .

[4]  F. Jonas,et al.  Poly(alkylenedioxythiophene)s—new, very stable conducting polymers , 1992 .

[5]  R. Friend,et al.  Structural order in poly(p-phenylene vinylene) , 1993 .

[6]  Julian Carter,et al.  Operating stability of light-emitting polymer diodes based on poly(p-phenylene vinylene) , 1997 .

[7]  S. M. Sze,et al.  Physics of semiconductor devices , 1969 .

[8]  C. C. Wu,et al.  Surface modification of indium tin oxide by plasma treatment: An effective method to improve the efficiency, brightness, and reliability of organic light emitting devices , 1997 .

[9]  C. J. Adkins,et al.  Intrinsic performance limits in transparent conducting oxides , 1992 .

[10]  F. Jonas,et al.  Conductive modifications of polymers with polypyrroles and polythiophenes , 1991 .

[11]  Richard H. Friend,et al.  An improved experimental determination of external photoluminescence quantum efficiency , 1997 .

[12]  Marie Angelopoulos,et al.  Polymeric anodes for improved polymer light-emitting diode performance , 1997 .

[13]  Kuen-Ru Chuang,et al.  Failure phenomena and mechanisms of polymeric light‐emitting diodes: Indium–tin–oxide damage , 1996 .

[14]  William R. Salaneck,et al.  The electronic structure of poly(3,4-ethylene-dioxythiophene): studied by XPS and UPS , 1997 .

[15]  R. Friend,et al.  Optical absorption and luminescence in poly(4,4′-diphenylenediphenylvinylene) , 1985 .

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

[17]  Yuji Hamada,et al.  Influence of the Emission Site on the Running Durability of Organic Electroluminescent Devices , 1995 .

[18]  B. Cumpston,et al.  Electromigration of aluminum cathodes in polymer‐based electroluminescent devices , 1996 .

[19]  I. Hamberg,et al.  Evaporated Sn‐doped In2O3 films: Basic optical properties and applications to energy‐efficient windows , 1986 .

[20]  S. Karg,et al.  Synthesis, electrical conductivity and electroluminescence of poly(p-phenylene vinylene) prepared by the precursor route , 1993 .

[21]  J. C. Scott,et al.  MEH-PPV Light-Emitting Diodes: Mechanisms of Failure , 1996 .

[22]  Ifor D. W. Samuel,et al.  Measurement of absolute photoluminescence quantum efficiencies in conjugated polymers , 1995 .

[23]  C. Tang,et al.  Organic Electroluminescent Diodes , 1987 .

[24]  Joseph Shinar,et al.  Effects of aquaregia treatment of indium-tin-oxide substrates on the behavior of double layered organic light-emitting diodes , 1997 .

[25]  M. Matsumura,et al.  Effect of a plasma treatment of ITO on the performance of organic electroluminescent devices , 1997 .

[26]  J. C. Scott,et al.  Degradation and failure of MEH‐PPV light‐emitting diodes , 1996 .

[27]  V. Cimrová,et al.  Anomalous electrical characteristics, memory phenomena and microcavity effects in polymeric light-emitting diodes , 1996 .

[28]  Takao Ishida,et al.  Structures and properties of electron-beam-evaporated indium tin oxide films as studied by x-ray photoelectron spectroscopy and work-function measurements , 1993 .

[29]  J. J. M. Vleggaar,et al.  Stability of polymer LEDs , 1998 .

[30]  Ching Wan Tang,et al.  Doped organic electroluminescent devices with improved stability , 1997 .

[31]  Chihaya Adachi,et al.  Molecular design of hole transport materials for obtaining high durability in organic electroluminescent diodes , 1995 .

[32]  M. Herold,et al.  Influence of the elimination temperature on light emitting devices prepared from poly(p‐phenylene vinylene) , 1996 .

[33]  Siegfried Karg,et al.  Bipolar charge and current distributions in organic light-emitting diodes , 1997 .

[34]  Franco Cacialli,et al.  Characterization of properties of polymeric light-emitting diodes over extended periods , 1994 .

[35]  Siegfried Karg,et al.  Increased brightness and lifetime of polymer light-emitting diodes with polyaniline anodes , 1996 .

[36]  C. R. Brundle,et al.  Electron Spectroscopy: Theory, Techniques and Applications , 1979 .

[37]  P. A. Cox.  The Electronic Structure And Chemistry Of Solids , 1987 .

[38]  Shigeo Fujita,et al.  Surface Treatment of Indium-Tin-Oxide Substrates and Its Effects on Initial Nucleation Processes of Diamine Films , 1997 .

[39]  Peter van de Weijer,et al.  Polymer light-emitting diodes: from materials to devices , 1997, Optics & Photonics.