Wetting Properties of Black Silicon Layers Fabricated by Different Techniques

The wettability of black silicon (BSi) layers fabricated by reactive ion etching (RIE), metal‐assisted chemical etching (MACE), and laser‐induced etching (LIE) techniques is studied. The contact angles of wetting on the samples with deionized water and methylammonium iodide‐based perovskite solutions are determined. It is found that the element composition and the enlargement area factor of BSi layers have a significant effect on their wettability. When tested with water, the RIE and MACE BSi layers exhibit hydrophobic properties, while the LIE BSi layer demonstrates hydrophilic properties due to the SiOx‐rich surface structures. It is also shown that aging leads to a decrease in the water contact angle. Upon exposure to perovskite solution droplets, BSi layers become highly lyophilic. Based on the Wenzel and Cassie–Baxter models, the mechanisms responsible for the wetting states of the fabricated samples are identified. In the results obtained, valuable insights are provided into the potential of using these layers in tandem perovskite/silicon solar cells.