Laser textured substrates for light in-coupling in thin-film solar cells

In this work, we investigate the use of a picosecond (ps) laser used for monolithic connection to texture three commercially available and frequently used multicomponent glasses, Corning EAGLE XG®, Schott BOROFLOAT® 33 and Saint-Gobain SGG DIAMANT®. The results show that the ablated crater profile and degree of texturing are glass composition dependent. This might be attributed to the different laser-induced electron collision times and recombination rates, and thus the critical electron density evolution leading to ablation. The surface texture is altered from periodic to random with decreasing scribing speed. The transmission of the textured substrates gradually decreases, whereas the multireflection on the surface increases as a consequence of the topological and morphological changes. The angular resolved measurements illustrate that the textured glass substrates scatter the light toward greater angles, which is necessary to increase the effective optical path in the absorber layer. Simulation results show that textured glass increases the absorption in the absorber material and the slightly modified refractive index region around the crater does not counteract the light in-coupling effect. The results suggest that these substrates can be used in various photovoltaic technologies and show potential for the application of alternative front contacts, such as carbon nanotubes.