Predictive electrical simulation
Using SimOLED's calculation features you can predict the device performance of even complex OLEDs. In the following example we have reproduced experimental data for current density and luminance in forward direction of a 5-layer phosphorescent OLED. The electrical material parameters have been determined in a similar way as described in Material characterization.
Device setup (click to enlarge)
The device is 5-layer p-i-n-type OLED with electrically doped transport layers and a green phosphorescent host-guest emitter layer (TCTA:Irppy). The OLED has been measured using three different thicknesses of the emitter layer in order to prove the predictive character of the electrical simulation. Our goal is to model the experimental data by one consistent parameter set for all thicknesses used.
Comparison between experimental data (lines) and simulations (symbols) (click to enlarge)
We could successfully reproduce the experimental data using only one consistent parameter set. This shows that by carefully determining the material parameters, predictive electrical simulations are possible.
Optical optimization of red OLED
With SimOLED you can easily optimize device performance. As an example we simulate maximum current-, power and external quantum efficiencies for a 5-layer red phosphorescent OLED using only the optical module.
Device setup for the example (click to enlarge)
It is a conventional p-i-n bottom emission OLED with electrically doped transport layers and NPD:Ir(MDQ)2(acac) as host-guest emitter system. Additionally, we have introduced a thin silver layer on top of the ITO to enhance outcoupling (see R. Meerheim et al., Appl. Phys. Let., Vol. 93, No. 4, 2008).
Varying the thicknesses of the doped hole transport layer and the silver layer at the same time using SimOLED's automatic parameter variation you can quickly find optimal values for current, power and quantum efficiency from the simulations.
Simulated luminous flux (proportional to Power Efficiency) as function of hole transport layer thickness (click to enlarge). Layer 2 (x-axis) is the HTM, layer 1 (y-axis) the Ag layer.
These values have been confirmed by the corresponding experiments. Note that we have introduced only one global scaling factor to bring the optical simulation into agreement with the experiments.
Total: comparision between experimental data (lines) and simulations (symbols) for current, power and external quantum efficiency, respectively (click to enlarge)
The excellent agreement between simulation and experiment confirms our optical modeling features implemented in SimOLED OPTIC.
Color maintanence of white hybrid OLED
In SimOLED PLUS you can calculate the color of your OLED as a function of applied voltage. For a white OLED this is quite important since its color may drastically change with varying voltage. The following example plots show simulation results of a white hybrid OLED calculated with the fully coupled (electrical + optical) mode of SimOLED PLUS.
Device setup for a white hybrid OLED with a green and red phsophorescent and a blue fluorescent emitter layer (click to enlarge)
By changing the thickness of the green and blue emitter using SimOLED's automatic parameter variation, you can quickly minimize the color shift with applied voltage.
Color point of the white hybrid OLED as a function of voltage. Left: large shift using 20 nm thick green emitter layer and 5 nm thin blue emitter layer, right: small shift using 5 nm green emitter layer thickness and 20 nm blue emitter layer thickness (click to enlarge).