Accurate and fast simulation of solar cell efficiency enhancement through excitation of plasmons at metal nanostructures.

It has been proposed to use metallic nanostructures for efficiency enhancement of energy conversion in solar cells (see e.g. Rockstuhl et al).
JCMsuite can be efficiently applied to simulate light scattering off periodic arrays of silver nanodiscs on a layer of amorphous silicon.

Fig. 1: Discretized geometry of a silver nano-disc (diameter: 140 nm, height: 65 nm) on a layer of amorphous silicon. The efficiency of the solar cell is enhanced by plasmonic light trapping.


Fig. 2: Relative error of the simulated absorption in amorphous silicon versus total computation time on a standard PC (single-processor usage, up to 4 GB RAM).With adaptive, higher-order FEM, very well converged results can be obtained in short times on a personal computer. Figure 1 shows a part of the discretization of the computational domain. Figure 2 shows how the accuracy of FEM simulations converges. Here, the convergence was investigated for light with a wavelength of 500 nm and perpendicular incidence. The different values were obtained using finite-element ansatz functions of polynomial order 1 to 5. Results with a relative error as low as 1 percent are obtained on a standard PC in roughly 10 seconds with a memory consumption of RAM of about 0.6 GB.






Fig. 3: Plasmon enhanced energy absorption spectrum, weighted with a sum of direct and circumsolar spectrum. The strong absorption peak around 500 nm is due to the excited plasmonic resonance.

Figure 3 shows the absorption spectrum of the photovoltaic (PV) cell. Computing such spectra using standard methods like FDTD or RCWA/Fourier modal methods can call for rather long computation times on supercomputers (see, e.g., Rockstuhl et al). Speed and accuracy advantages of FEM / JCMsuite compared to standard methods allow for design optimizations of metallic nanostructures on solar cells on a larger parameter space. JCMsuite also allows to perform such computations using relatively cheap and less energy-consuming standard personal computers.
Rockstuhl et al - Publication on Absorption enhancement in solar cells by localized plasmon polaritons.
FEM / JCMsuite - Simulation method for improved accuracy in nanooptics design.