Laoss is a powerful software to simulate large area semiconductor devices (OLEDs, thin-film PVs), taking into account the voltage drop in the electrodes due to important resistive effects when the size of the device increases.
Simulation of large area semiconductor devices (OLED, thin-film PV)
Coupling law input: analytical or tabulated (experimental or simulated) IV curve
Device optimization (electrode material, device geometry etc...)
High speed computation
Coupled Electro-Thermal Modeling
Laoss contains a coupled electro-thermal model which simulates the two-way interaction between heat generation and electrical properties of the semiconductor. Heat is generated by the organic semiconductor stack itself and by Joule heating in the electrodes. In turn the current voltage characteristics change depending on the local temperature of the semiconductor device.
Laoss has been successfully tested, confronting its results with several experimental results contained in the paper: K. Neyts et al.: “Inhomogeneous luminance in organic light emitting diodes related to electrode resistivity", J. App. Phys., 100, 114513(2006).
Here we present one of the results, which shows a clear agreement between Laoss simulation results and Neyts’ luminance position dependence.
Applications such as geometry optimization and material choice can be realized with Laoss, leading to substantial time and resource savings.
Metal finger width optimization:
metal finger (metal grid) can be added to the transparent electrode of a PV cell in order to improve its conductivity, and as a consequence to improve the device efficiency. In this case the width of the metal finger has been optimized in order to find the best compromise between two counter-acting effects: shadowing due to the metal finger and low conductivity due to the absence of a metal finger.
Electrode material choice:
Two important electrodes properties are its transparency and conductivity. Choosing the most efficient material is not an easy task since the relative impact of the conductivity and transparency change with the device size. In this case is shown how Laoss can be easily used to produce a chart of the best material choice for a PV cell depending on the device size.
Sample 1: Transparency = 85%, σ = 1.14x10^6 S/m
Sample 2: Transparency = 90%, σ = 6.67x10^5 S/m
Laoss modeling for OLEDs and PVs can produce a wide range of different output data, such as IV curves, Fill Factor vs. conductivity graphs, 2D visualization of electrodes electric potential, current density and dissipation, total output power….
Electric potential in an electrode with a metal grid for conductivity improvement.
Laoss produces accurate IV curves for device characterization, which allows for the extraction of its main parameters: Voc, Isc, FF, Pmax.
Electric potential along the horizontal axis of an electrode with a metal grid for conductivity improvement.
Fill factor study in function of the conductivity, converging towards the ideal case of a perfectly conducting electrode.
Current density flowing in an electrode with a metal grid for conductivity improvement.