Light Trapping in Thin-Film Silicon Solar Cells with Periodic Structures

The fundamental optics of microcrystalline thin-film silicon solar cells with integrated 1D line grating couplers, 2D and 3D pyramidal interfaces were investigated by means of numerical modelling. The simulated QE for a 1D grating is in good agreement with experimental data. The discussion of the blue response based on the measured and calculated reflection shows that a binary shaped grating does not lead to a significantly improved light in-coupling whereas the shape of the grating has a significant influence on the blue light incoupling properties of the solar cell. Only in the case of an insufficient diffraction at the textured TCO/p-interface an additional scattering at the back contact can improve the light trapping properties of the cell. As an alternative to randomly textured layers periodically textured structures were integrated in thin-film solar cells and their optical properties were investigated. The simulations predict that the highest current densities can be achieved for a solar cell with a 3D pyramidal interface