Nanopyramid Texture Formation by One‐Step Ag‐Assisted Solution Process for High‐Efficiency Monocrystalline Si Solar Cells

Abstract

In monocrystalline Si solar cells, pyramidal surface textures with the size of a few micrometers (micropyramids) are commonly applied for light in‐coupling and trapping. Recently, there is a growing need to reduce the size of pyramids below 1 μm. Herein, an original method to fabricate nanometer‐sized pyramids (nanopyramids) featuring an average size of ≈500 nm or even smaller by using a simple one‐step Ag‐assisted solution process is proposed. The texture size can be controlled by the concentration of AgNO3 in the alkaline etching solution where the generated Ag nanoparticles act as an etching mask as well as promoting the detachment of H2 bubbles from the reacting Si surface. This process enables the formation of uniformly distributed Si nanopyramids with a lower reflectance below 10% and a smaller etching margin less than 1.7 μm compared with the conventional micropyramids. Silicon heterojunction solar cells employing Si nanopyramids outperform those with the conventional micropyramids owing to the reduced optical reflectance while preserving excellent surface passivation and carrier transport properties. These results demonstrate the advantages of our method and the high potential of Si nanopyramids for various applications such as thin crystalline Si solar cells and perovskite/Si tandem solar cells.