Hierarchical robust textured structures for large scale self-cleaning black silicon solar cells

Abstract

Hierarchically textured Si is explored for low reflection, and self-cleaning solar cells, which was fabricated from micropyramids with nanostructures that were added by Au-assisted electroless chemical etching. Such a structure creates a graded effective refractive index from air to Si and leads to a black appearance due to broadband reflection suppression in the 300–1200nm range. A front average weighted reflectance of 1.4% was achieved, which is one of the lowest values reported for black Si solar cells. Variation in the size of the nano-scale texture was found to have greater impact on the reflectance of the hierarchal structure than the size of the micro-scale pyramid texture. The hierarchial texturing was applied to a cost effective screen-printed, aluminum back-surface field solar cell resulting in a conversion efficiency of 16.5%. In addition, the hierarchical structure features mechanical robustness and self-cleaning properties.