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With the goal of reducing manufacturing costs and material inputs and increasing solar cell efficiencies, research into solar cells is increasingly focused on new cell design concepts including thin film, organic, and textured surface solar cells. When incorporating nanophotonic elements like metallic nanoparticles with plasmon resonances tuned to efficiently scatter the light into the absorbing layer, or nanotextured surface anti-reflection coatings to reduce undesirable back reflections that degrade cell performance, solar cell performance can be dramatically improved.
Simulation of solar cells is essential to predict the behavior of these devices. As the design of photovoltaic cells increase in complexity, it becomes more difficult to obtain analytic solutions for their performance. In the real device, non-ideal processes such as bulk and surface recombination of electrical charge carriers (electrons and holes) reduce the electrical efficiency of the solar cell. A combination of optical and electrical simulations which account for these non-ideal processes are necessary to accurately characterize the photovoltaic efficiency of the solar cell.
FDTD Solutions is a high performance optical solver that can be used to simulate the interaction of light with a wide variety of solar cell designs. These designs can range from simple planar geometries to very complex patterning, and can include a wide variety of materials such as organics and metals.
The result of the optical simulation is the spatial absorption in the substrate region, from which one can calculate the generation rate. This generation rate can be used in an electrical simulation in DEVICE to determine the responsivity and the photovoltaic efficiency of the solar cell. The CHARGE solver in DEVICE will account for the distribution of dopants that give rise to the built-in electric fields, the mobility of free carriers and the physical processes that result in the recombination of charge.
The solar cell workflow starts with optical simulations in FDTD Solutions. Taking the solar spectrum into account, the generation rate is calculated from the optical absorption and used as a source in the subsequent electrical simulation in DEVICE to calculate the quantum efficiency.
•Build a 3D model of your textured surface solar cell design
•Generate highly-accurate material models over the entire solar spectrum using Lumerical's proprietary multi-coefficient materials
•Accurately model semiconductor materials accounting for surface and bulk recombination through detailed models. Define your own semiconductor material models, or use predefined models for common semiconductors like silicon.
•Obtain accurate broadband results at multiple wavelengths in a single simulation
•Characterize the solar cell for incoherent and unpolarized response, properly accounting for the spectral intensity (e.g. AM1.5) of the sun
•Calculate the spectral transmittance into the solar cell
•Calculate the spatial absorption profiles and resulting quantum efficiency for different surface patterns
•Calculate the collection efficiency of electron/hole carriers for arbitrary optical generation spatial profiles, imported from 3D FDTD simulations or other optical simulation tools
•Characterize your device and calculate device performance metrics like energy conversion efficiency, quantum efficiency, fill factor and maximum power point
•Optimize your solar cell using the build-in parameter sweep and optimization utility See a simple example for an anti-reflecting multilayer stack.