Enhanced optical absorption and electrical performance of silicon solar cells due to embedding of dielectric nanoparticles and voids in the active absorber region
Dielectric nanoparticles and voids have been embedded in the active silicon layer of standard silicon nitride-coated planar solar cells with a view to decouple the scattering properties of the nano entities (dielectric nanoparticles and voids) from their antireflection properties. However, it was found that complete decoupling between the two is not obtained. Our study shows that the additional reflection losses due to embedding may be partially or fully offset by the enhanced scattering, leading to net increase in absorption inside the solar cell for many embedding configurations depending on the nano entity material, size, area coverage, and depth of embedment. Optical simulation results were then incorporated into the electrical device model to obtain the solar cell parameters. Relative improvement of 7.1% in the efficiency of 20 μm thick solar cell has been obtained for 200 nm radius voids embedded 300 nm deep with 30% coverage. The relative improvement in efficiency is lower (1.9%) for 200 μm cells and higher (27.5%) for 2 μm cells.