Characterize your optoelectronic device or design it to satisfy given requirements. Setfos allows for easy modeling, optimizing, tuning of the device performances and let you share the results with your colleagues or project partners.
Among the different characterization tasks:
- emission color matching
- luminance maximization
- Analysis of optical modes and photon statistics
- exciton kinetics
- emission zone extraction in OLEDs and many more...
Emission color matching
Setfos optimization routines can be exploited to design the right combination of layer thicknesses that lead to a particular emission color in OLEDs.
Instead of systematically varying the HTL layer thickness in order to find which configuration emits the needed color, let Setfos find the optimum in few seconds.
- CIE color diagram for different HTL thicknesses in the structure depicted above.
- Calculated emitted color for different HTL thicknesses in the structure depicted above.
Setfos optimization routines finds after few seconds the optimum HTL thickness to emit green light with CIE_x coordinate 0.3 to be 24.7 nm. Operating such a device at 10 mA/cm2 you get following key figures:
# Radiance: 1826.22 W/m2/sr
# Luminance: 12.1156 cd/A
# Peak Intens.: 19.5874 W/m2/nm/sr
# Peak at: 526 nm
# CIE_x: 0.3
# CIE_y: 0.579996
# Lum.Effcy: 453.117 lm/W
# CRI: 21.5081
# SEIR: 0.203299
# SIA: 0.52237.
- Emission spectrum of the optimized structure and visualized colors for reflected light, device emission and intrinsic material luminescence.
Analysis of Emission Modes in OLEDs
Besides light emission spectra and key figures like Color Rendering Index (CRI) or Luminous Efficacy, Setfos can quantify the power emitted into different optical modes of the multilayer structure.
- Figure 1: Average contribution of the generated optical power to the different extraction modes as a funktion of the mean dipole position.
The powerful features of Setfos allow to optimize the device structure for improved outcoupled optical power radiated by the emitting dipoles.
Quantify top and bottom emitted power, absorption loss, energy trapped in the layer stack and coupling to evanescent modes at metal interfaces! Study the dipole dynamics and gather interference induced lifetimes and quantum yield of the emitting state.
OLED Efficiency Optimization with High-index Substrates
It has become evident that the light-outcoupling efficiency of OLEDs can be improved dramatically if a) the light can escape from the multilayer thin films into the glass substrate and b) the substrate mode can be coupled out by suitable outcoupling structures at the substrate-air interface. Mikami and Koyanagi (Mikami, SID 2009 proceedings paper) demonstrated that efficiencies beyond 200 lm/W can be reached.
- Left: Setfos simulation result for the OLED emission modes dependent on the substrate refractive index.
- Right: Reference calculation result by Mikami et al. (SID 2009 proceedings).
Once the light has reached the substrate, it is often difficult to get it out of there without 3 dimensional over-structures like surface gratings and/or micro-lenses.
Setfos allows you to quantify the characteristic grating period matching the k_inplane vector of the majority of the photons within the glass. Alternatively you can quantify the angle under which most photons are propagating at, in order to separately design the suitable micro-lens.
- Left: for a structure that captures 27.3% of the optical power in the substrate glass, potentially 10% of the photons can be extracted with a grating with a pitch Λ=420 nm (K~0.015nm-1).
- Right: for a structure that captures 27.3% of the optical power in the substrate glass, potentially 13% of the photons propagate within the glass under an angle of 60° (n_eff=1.3).
- Figure: Dipole lifetime calculation for a thin Eu+ layer on a dielectric film on silver. The thickness of the dielectric film was varied, c.f. Chance et al.
Radiative Lifetime of Emissive Dipoles
Setfos can quantify the power dissipated in each emission mode for a multiple set of parameters (e.g. wavelength, layer thicknesses and refractive indices) and for several emission zones.
Setfos reproduces calculation results published by R. R. Chance et al., "Fluorescence and energy transfer near interfaces: The complete...", J. of Chemical Physics, Vol. 63, (1975) [fig. 6], who published the original dipole emission model that was used to describe fluorescence lifetimes of Eu+ separated by a fatty acid layer from a silver layer.
Extraction of the Emission Profile from Angle-resolved Radiance
Setfos allows to optimize scalar quantities like the Radiance, which is the integration of the emission spectrum. Further, it can find an optimal combination of parameters which represents a measured radiance as a function of the observation angle best. We measured the radiance of a PLED at different angles ranging from 0 deg to 88 deg in steps of 4 deg. The assumed dipole distribution has Gaussian characteristics (the user can alternatively choose an exponential shape, of a delta distribution). Setfos searches for the center of the peak and the width of the distribution that produce an emission characteristics fitting with the measured one.
- Left: Reference emission intensities to be fitted through the optimization algorithm.
- Right: Fitted emission intensities where the extracted dipole distribution parameters are 0.7 for the dipole location and 30 nm for the shape width.
