Fabrication of silicon nanopillar arrays by cesium chloride self-assembly and wet electrochemical etching for solar cell

- CsCl self-assembly and wet electrochemical etching can make nanopillars texture.
- Nanoporous gold film as the catalyst is formed by CsCl nanoislands lift-off.
- Wafer scale nanopillars of height from 3 to 12 μm are obtained by this method.
- The lowest reflection brought by 9 μm height nanopillars is below 3%.
- The best PCE brought by 3 μm height nanopillar based solar cell is 14.19%.

A simple technology with cesium chloride (CsCl) self-assembly lithography and wet electrochemical etching is introduced to fabricate the wafer scale, disordered, well-aligned, and high aspect ratio silicon nanopillars. The original nano structures of CsCl islands with diameters of 500-2000 nm are formed by self-assembly and used as template of lift-off for the nanoporous gold film for wet electrochemical etching as the catalyst in etching solution of HF and H2O2. The average diameter of silicon nanopillars is determined by the CsCl nanoislands with 500-2000 nm, and the height of silicon nanopillars is mainly determined by the etching time in etching solution with 3-12 μm. The aspect ratio can achieve to 60. The solar cells with different height nanopillars are made for the research of photovoltaic conversion efficiency (PCE). The reflectance of the nanopillars with different height is measured from the wavelength of 400 to 1000 nm and the 9 μm height silicon nanopillars has the lowest one which is below 3%. The PCE shows the highest value of 14.19% at the condition of 3 μm height nanopillars and 12.18% of planar one with the same fabrication process.