A typical preparation procedure of silica nanoparticles is as
follows [32]: ammonia solution and anhydrous ethanol (NH3OH:
ethanol=3/50, in volume) were stirred at 70 °C for 30 min, then
TEOS with the same volume to ammonia solution was slowly
added into the mixture and then stirred vigorously for 1.5 h. The
resultant silica nanoparticle sol was kept in an oven at 30 °C for
about 7 h to let SiOH further react each other and to increase
the viscosity of the sol. The silica film was fabricated by dipcoating
the cleaned glass in the silica sol with a withdrawal
speed of approximately 2.5 mm/s. The coating was dried under
ambient condition for 10 min and then treated at 200 °C for 1 h.
Then the silica films were UV-irradiated in ozone for 20 min.
Thus, the superhydrophilic films with antifogging property
formed. To improve the robustness of the silica film, the resultant
film was calcinated at 500 °C for 1 h in the oven. To investigate
the antireflective effect of the prepared film on the output of
solar modules, full sized cover glass was roller coated with the
silica sol and then was manufactured on the solar panels in
CEEG (Shanghai) Solar Science & Technology Co., Ltd.