Fabrication of micro-nano surface texture by CsCl lithography with antireflection and photoelectronic properties for solar cells

A pyramid and nanopillar micro-nano surface texture of silicon wafer, which has pyramid arrays about 4–8 μm with different nanopillars of average diameter from 100 to 500 nm and height from 500 nm to 1.5 μm, is fabricated by Cesium Chloride (CsCl) self-assembly lithography and dry etching for solar cell. This micro-nano surface texture with 100 and 200 nm average diameter has very good antireflection with reflectance below 5% for the wavelength ranging from 400 to 1000 nm and much lower than that of single pyramid or nanopillar arrays with the same average diameter. The reflected distribution of this micro-nano structure illuminated with white parallel light at incidence angle of 45° is tested by a irradiatometer at the reflected angle from 10 to 80 degree and shows a total diffuse and very low reflection at different reflected angles, which benefits from both the advantages of nanopillar and pyramid structure. The solar cell with this micro-nano texture has been finished with thermal diffusion of Phosphorus for P–N junction and printing silver plasma for front electrode poles, and its photovoltaic conversion efficiency is about 7.05% which is higher than that of solar cell only with the planar, single pyramid or nanopillar and made with the same fabricating process.