Theoretical short-circuit current density for different geometries and organizations of silicon nanowires in solar cells

Radial junction solar cells are providing promising advantages of efficient light trapping and high built-in field when compared to their thin films or wafer based counter parts. In this work, we model short-circuit current densities for a wide range of nanowire arrays in order to define their optimal configurations. The modeling focuses on the fundamental nanowire properties, such as the nanowire length and the diameter, but also on their organization and on their density. The short-circuit current density is evaluated using rigorous coupled-waves analysis and normalizing the spectral absorptance by the standard AM 1.5 G solar spectrum. Results show that the nanowire density and length have the major impact on the device performance, while the nanowire organization is less important. Efficient light trapping properties of individual nanowires play an important role in the device performance and they have been further exploited in double-diameter nanowire arrays. An introduction of two different nanowire diameters into the same structure allowed for a separated optimization in two different spectral regions. As a result, we are reporting 10% increase in the short-circuit current density when double-diameter nanowire arrays were used.