Device model investigation of single layer organic light emitting diodes

We present calculations of single layer organic light emitting diode (LED) characteristics using a device model which includes charge injection, transport, recombination, and space charge effects in the organic material. Contact limited and ohmic contacts, high and low carrier mobilities, and device thicknesses from 5 to 200 nm are considered. The scaling of device current with applied voltage bias and organic film thickness is described for contact limited and ohmic contacts. Calculated device current, light output, and quantum and power efficiency are presented for representative cases of material and device parameters. These results are interpreted using the calculated spatial variation of the electric field, charge density, and recombination rate density in the devices. We find that efficient single layer organic LEDs are possible for a wide range of organic material and contact parameters. (C) 1998 American Institute of Physics. [S0021-8979(98)03814-6]