General purpose
Setfos is a versatile numerical tool that allows you to fit measurement curves of both optical and electrical experiments to extract important physical parameters like:
- exciton lifetime
- refractive index dispersion
- charge mobilities
- intrinsic luminescence spectra and many others...
Exciton/dipole lifetime and quantum efficiency
Measuring the radiation kinetics of Eu+ ions depending on the distance from a metallic surface allows one to calculate their intrinsic lifetime and quantum efficiency. We present here the fit of the lifetime curve to the measured data published by Chance et al., Journal of Chemical Physics, Vol. 63, pp. 1589ff, (1975).
The published values for the Eu+ ion lifetime and quantum efficiency are 632 us and 0.76, respectively. Setfos finds τ=634.382 us and q0=0.747945.
Mobility extraction from IV curve measurements
The fast steady-state solver implemented in Setfos allows one to fit IV curves of single-layer devices faster than ever. Material characterization is now therefore accessible directly after a simple measurement.
Extracted Poole-Frenkel hole mobility parameters for the investigated MEH-PPV compound are μ0=8e-08 cm^2/Vs and γ=0.00400098 cm^0.5/V^0.5.
Mobility parameter extraction from transient measurements, Photo-CELIV
Charge extraction by linearly increasing voltage (CELIV, Juska et al., Phys. Rev. Lett. 84, 21, (2000)) has become a powerful experimental technique for determining the charge carrier mobilities and recombination effects in solar cells. Setfos can simulate photo-CELIV and CELIV photocurrents and provide superior analysis of measured data.
The value added by simulation to the characterization procedure is the clear distinction between fast and slow carriers: The first sharp peak of the measured current (red solid line) relates to the fast electron extraction at the cathode while the second blunt peak is due to the slow holes extracted at the anode.
- Single layer polymeric structure investigated for the PL measurement experiment.
- Measured (red dots) and calculated (blue line) emission spectra.
Extraction of the intrinsic PL spectrum
Measured luminescence spectra from thin films suffer from interference effects due to multilayer structures that shift the actual, material specific radiation spectrum.
Setfos gets rid of the interference effects and calculates the intrinsic PL (source) spectrum of your emissive material from a simple photo-luminescence measurement. In addiction, the spatial emission zone is also extracted.
Fits can be performed for a fixed observation angle or be combined in a spectral-angular extraction procedure.
Notice the red-shift of the measurable emission spectrum with respect to the intrinsic source spectrum. A clear sharpening of the peak due to resonant effects is also observed.
- Extracted intrinsic luminescence spectrum of the investigated emissive polymer.
- Extracted emission distribution of the radiating dipoles.
- Experimental structure with a thin polymeric film on a thick glass substrate.
Refractive index dispersion parameters
In Setfos the user can express the refractive index dispersion through tabulated values or by means of an analytical formula: implemented models are: Cauchy, Sellmeier, and Tauc-Lorentz.
The parameters characterizing such dispersion functions are varied by the software to fit e.g. Reflection and Absorption spectra.
Depending on the purposes and required precision, several oscillators from different models can be combined to reproduce the material dispersion best.
Here a single Sellmeier oscillator is assumed to reproduce the dispersion of P3HT-PCBM as tabulated by Monestier et al., Solar Energy Materials and Solar Cells, vol. 91 (5), pp. 405-410 (2007) from reflection and absorption measurements.
- Graph of the tabulated P3HT-PCBM dispersion.
- Graph of the extracted analytical dispersion from a single Sellmeier oscillator.
