Numerical simulations of the electrical characteristics and the efficiencies of single-layer organic light emitting diodes

We have used numerical methods to calculate the current and the efficiency of single-layer organic light emitting diodes, taking into account field-dependent mobilities, diffusion, and thermionic injection at the metal/organic interfaces. It is shown that when the barrier for charge injection from the metal to the organic is lower than 0.3 eV, the contact is, for practical purposes Ohmic, supplying the bulk of the organic layer with a space charge limited current. Determination of the carrier mobility by fitting experimental current–voltage data is discussed and the voltage dependence of the current and the efficiency are analyzed. The recombination profile is shown to evolve with voltage, shifting towards the electrode which injects the carrier with the lower mobility. The numerical results are compared with experimental data from poly[2-methoxy,5-(2-ethylhexoxy)-1,4-phenylene vinylene] (MEH-PPV) based devices.

[1]  George G. Malliaras,et al.  Charge injection and recombination at the metal–organic interface , 1999 .

[2]  E. H. Rhoderick,et al.  Metal–Semiconductor Contacts , 1979 .

[3]  Smith,et al.  Direct measurement of conjugated polymer electronic excitation energies using metal/polymer/metal structures. , 1996, Physical review letters.

[4]  Siegfried Karg,et al.  Charge carrier mobility in poly(p-phenylenevinylene) studied by the time-of-flight technique , 1997 .

[5]  K. Kao.  Double injection in solids with non-ohmic contacts. I. Solids without defects , 1984 .

[6]  Yongsup Park,et al.  Dramatic photoluminescence quenching of phenylene vinylene oligomer thin films upon submonolayer Ca deposition , 1996 .

[7]  Dunlap,et al.  Charge-Dipole Model for the Universal Field Dependence of Mobilities in Molecularly Doped Polymers. , 1996, Physical review letters.

[8]  P. Blom,et al.  Temperature dependent electron-hole recombination in polymer light-emitting diodes , 1997 .

[9]  P. Murgatroyd,et al.  Theory of space-charge-limited current enhanced by Frenkel effect , 1970 .

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

[11]  S. Shaheen,et al.  A model for the current–voltage characteristics and the quantum efficiency of single-layer organic light emitting diodes , 1997 .

[12]  H. Bässler,et al.  Models of organic light-emitting diodes , 1997 .

[13]  V. M. Kenkre,et al.  Dispersive aspects of the high-field hopping mobility of molecularly doped solids with dipolar disorder , 1997 .

[14]  M. Lampert,et al.  Current injection in solids , 1970 .

[15]  P. Blom,et al.  Electrical characterization of polymer light-emitting diodes , 1998 .

[16]  H. Grubin.  The physics of semiconductor devices , 1979, IEEE Journal of Quantum Electronics.

[17]  Vladimir Arkhipov,et al.  Charge injection into light-emitting diodes: Theory and experiment , 1998 .

[18]  George G. Malliaras,et al.  Electrical characteristics and efficiency of single-layer organic light-emitting diodes , 1998 .

[19]  George G. Malliaras,et al.  The roles of injection and mobility in organic light emitting diodes , 1998 .

[20]  Peter A. Torpey,et al.  Double‐carrier injection and recombination in insulators, including diffusion effects , 1984 .

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

[22]  Jie Yang,et al.  Physical mechanisms in double-carrier trap-charge limited transport processes in organic electroluminescent devices: A numerical study , 1998 .

[23]  I. Campbell,et al.  Device model investigation of single layer organic light emitting diodes , 1998 .

[24]  Paul Davids,et al.  Device model for single carrier organic diodes , 1997 .

[25]  George G. Malliaras,et al.  Injection, transport, and recombination in organic light-emitting diodes , 1998, Optics & Photonics.