Simulate IV Curves with Drift-Diffusion

The electrical performance of OLEDs & solar cells is governed by the Drift-Diffusion equations. Setfos' Drift-Diffusion module calculates the IV curve, charge concentration, electric fields and recombination zone of OLED & PV devices. The charge transport in organic semiconductor materials is expressed by the mobility & HOMO/LUMO of the organic molecules. A range of material properties can be simulated in Setfos.

  • Simulate IV-curves, impedance spectroscopy and transient responses (incl. photo-CELIV).
  • State-of-the art mobility models: Poole Frenkel, EGDM/ECDM, constant mobility
  • Conductive doping & charge trapping mechanisms
  • Injection properties
  • Exciton recombination, generation, quenching, roll-off, diffusion, fully coupled to optical emission and absorption

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DC, AC & Transient Simulation

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Setfos calculates the IV curve of OLED & PV devices using mobility and energy level positions including traps, doping, recombination and illumination.

Setfos Impedance solver calculates the equivalent impedance and capacitance. The physical equations are solved instead of an equivalent circuit approximation.

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Transient simulations reveal material dynamics not visible in IV curves. Simulate experiments like transient electroluminescence (TEL), dark injection transient (DIT), CELIV, exciton decay rate...

Doping & Trapping

Simulated IV Curves with and without using shockley-read-hall recombination.

Simulated IV Curves with and without using shockley-read-hall recombination.

Addition of doping material is a key method to improve conductivity. Impurities in the evaporated or solution processed materials introduce trap states that influence the charge transport. Deep traps act as recombination centers via the Shockley-Read-Hall mechanism (SRH). A permanent polarity of the charge transport layer can effectively improve the injection.

Use Setfos simulations to reproduce, quantify and understand the influence of these effects.

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Exciton Physics

Excitons form the link between electrical charges and emission and absorption of light. Setfos' coupled opto-electrical simulation models the recombination and dissociation of electron-hole pairs.  As well as their diffusion, radiative and non-radiative decay paths are calculated. Setfos even models transfer between different excitons like in TADF emitters.

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Exciton Processes in OLEDs

Setfos simulates the full formation and decay process of excitons in an OLED.

  • Radiative decay and light emission including Purcell quenching effects.
  • Non-radiative decay and IQE
  • Formation, diffusion and dissociation of excitons
  • Efficiency roll-off via triplet-triplet (TTA) and triplet-polaron (TPQ) interaction.
  • Exciton transfer via TADF
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Exciton Processes in Solar Cells

The absorbed photons create an electron-hole pair inside the solar cell. The electron hole pair dissociates to generate the photo-current of a solar cell.

  • Langevin or Onsager-Braun recombination model
  • Calculate the optimal thickness of the absorbing layer
  • Calculate recombination losses & fill factor

Comprehensive Device Modeling

Experiments seldom match with theoretical expectations that are based on simplified device models. By detailed simulation of the experiments, the empirical behaviour of the sample can be closely modeled. Not just one experiment but a series of measurements can be investigated to build a comprehensive device model.

Setfos-Paios Integration integrates the Setfos Drift-Diffusion solver to the DC, AC and transient measurement performed with Paios. Closer reproduction of the measured curves means greater confidence in extracted parameters and more consistent material characterization.

 

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EMISSION

EMISSION

Absorption

Absorption

Light ScaTTering

Light ScaTTering