Fig. 1. Fabrication procedure diagram of two-dimensional （2D） composite grating

Fig. 2. SEM images of the as-prepared grating

Fig. 3. Reflected spectra of flat PDMS， 1D PDMS grating and 2D PDMS composite grating

Fig. 4. Rreflected spectra of epoxy resin encapsulated Si solar cell with flat surface， 1D grating and 2D composite grating

Fig. 5. J-V curves of epoxy-resin-encapsulated solar cells with flat surface， 1D grating and 2D composite grating antireflection coatings， respectively

Fig. 6. Contact angle of a 2-μL deionized water droplet on flat epoxy resin， 1D grating and 2D composite grating

Fig. 7. Surface cleanliness photos of epoxy resin with or without 2D composite grating structure after pollution， nitrogen blowing and water washing