Abstract:
Silicon solar cell photovoltaics offer the possibility of harvesting almost limitless
electromagnetic energy radiated from the sun. However, wide-spread adoption
of these solar cells requires that greater conversion efficiencies can be attained at
cheaper costs than that available with current bulk silicon solar cell technologies.
Fundamental loss mechanisms such as the transparency of the materials at longer
wavelengths and carrier thermalization effects can be greatly reduced by realizing
tandem solar cells. On the other hand, a thin film solar cell with proper photon
management can absorb adequate light with low material consumption. Subwavelength
nanostructures, especially plasmonic nanostructures have emerged as
an exciting research area to increase the light trapping in thin film solar cells. In
this thesis, we have investigated light management of a-Si/ c-Si tandem thin film
solar cells with metallic nanostructures supporting plasmonics usingFDTDnumerical
tool. Our study shows that coupling light to the bottom active region ( c-Si) is
challenging at shorter visible wavelength regime of solar spectrum in a a-Si/ c-Si
tandem structure due to high absorption coefficient in a-Si top active layer and light
management structures are required to enhance bottom layer absorption. Monolithically
grown tandem solar cells are susceptible to current mismatch in different
active region. We have investigated intermediate metal contact layer with light
opening for the bottom active layer as an new approach to make tandem structure
insensitive to current mismatch. In our study, we found an overall absorption of
61% in 300 nm of active material of silicon.
