  Broadband and omnidirectional antireflection coating is a generally effective
way to improve solar cell efficiency, because the destructive interference
between the reflected and input waves could maximize transmission light in the
absorption layer. Several theoretical calculations have been developed to
optimize the anti-reflective coating to maximize the average transmittance.
However, the solar irradiances of the clear sky spectral direct beam on a
receiver plane at different positions and times are variable greatly. Here we
report a new theoretical calculation of anti-reflective coating with incident
quantum efficiency {\eta}in as evaluation function for practical application.
The two-layer and three-layer anti-reflective coatings are optimized over
{\lambda} = [300, 1100] nm and {\theta} = [0{\deg}, 90{\deg}] for cities of
Quito, Beijing and Moscow. The {\eta}in of two-layer anti-reflective coating
increases by 0.26%, 1.37% and 4.24% for these 3 cities, respectively, compared
with that other theoretical calculations due to better match between the local
actual solar spectrum and quantum efficiency spectrum. Our numerical simulation
and comparison data with other optimization methods suggest that this
optimization method combining ant colony algorithm method with SPCTRL2 solar
spectral irradiance can effectively push the efficient solar cell toward higher
quantum efficiency, thus enabling high utilization efficiency of solar
irradiance.
