Optical Modeling of Ultrathin Silicon Solar Cells with PC1D

Abstract

We show that the optical diffusion model embedded in the numerical simulation program PC1D systematically underestimates light-generated currents in thin textured Si solar cells. The demonstration exploits the exact analytical solution to minority-carrier transport in uniformly doped regions and the fact that, at the first pass of internal light, the average optical propagation angle, θ, with respect to the device normal is determined by surface texture. We provide a simple correction procedure to remove the aforementioned systematical error. One can so reliably model with PC1D the optical performance of textured thin devices at standard Lambertian regimen (θ = 60° at all wavelengths, λ) that starts at either the first or the second pass of trapped light. We exploit such a possibility to scrutinize with PC1D a reported non-standard Lambertian optical model, where θ varies with λ.