CPV (Concentrated Photovoltaics) is an emerging technology for developing high-efficiency, low-cost solar cells. CPV uses optics such as mirrors or lenses to capture the sunlight in a more effective manner. In this study, closed-packed arrays of nanoscale dielectric spheres (nanospheres, NS) located on top of the cell, can be utilized as lenses which increase the absorption of c-Si solar cells. NS can reduce the reflection and suppress the transmission by changing the incident light into a set of collimated beams. NS can focus the light inside the photovoltaic layer which causes an increase in the absorption and consequently in the photovoltaic current. The fabrication of such light-trapping structure is low-cost and less complicated than standard alternatives such as vacuum evaporated multilayer anti-reflection coatings. We find that by using silica NS, the efficiency improvement is limited by the spherical shape of the NS causing premature focussing due to sphere shape. For that reason, we proceeded with polystyrene NS in which we were able to show further improvement in the solar cell efficiency by annealing based shape adjustment of NS.
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