2 layers versus 3 layers OLED

organicex04.in : 2 layers versus 3 layers OLED

Requires: Blaze/Organic Display
Minimum Versions: Atlas 5.24.1.R

A conventional 2 layer organic light emitting diode consists of a Hole Transport Layer (HTL) and an electron transport layer (ETL). A good OLED structure requires sufficient carrier injection so that large exciton density is generated when the carriers recombine. However, a 2-layer OLED structure has a low injection current due to the poor metal/organic material interface and therefore has a low device output efficiency. Commercial OLED structures are multi-layers and this example compare 2 layers versus 3-layers OLED.

This example is based on the following reference:

J.Staudigel et al, "A quantitative numerical model of multilayer vapor-deposited organic light emitting diodes" Journal of Applied Physics Vol. 86, Number 7 October 1999

In the first part on this example a hole-only unipolar organic device is simulated and simulation result is compared to measurement. Schottky contacts are defined for both anode and cathode electrodes and defect states are defined whithin the organic material using the odefect statement. A good fit is obtained between simulation and measurement.

The second part of the deck compare a 2 layers OLED versus a 3 layers OLED.

To demonstrate why the 3-layer OLED has a higher efficiency than a 2-layer device, we need to take into account interface defect between organic/organic material. To do so we have defined interface defect states using the ointdefect statement combined with interface thermionic emission model. The main effect of the organic/organic interface is to add trap states which reduces the energy barrier height and enhance carriers injection.

Simulation results indeed show thatthe 3 layers OLED has a lower anode current as expected but a higher luminescent power due to higher Langevin recombination rate. The same simulations done without interface defect states show opposite behavior (i.e luminescent power is higher in 2 layers OLED).

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.