Theoretical solar cell efficiency limits increase with optical concentration of sunlight while the usage of expensive absorber material decreases. In practice, the efficiency of concentrator solar cells peaks already at a few hundred Suns and drops sharply thereafter due to a trade-off between shading losses due to the front metal grid and resistive heating losses of the cell. In this work we deposit a transparent polymer layer with V-shaped grooves, imprinted above the cell’s metal fingers, which redirects light away from the metal and onto the absorber material. This renders the contacts effectively transparent and breaks the trade-off, thus allowing for higher concentration ratios and higher efficiency. We will demonstrate how performance of a Si solar cell with 25% front metal grid coverage and an initial short-circuit current density (JSC) of 29.95 mA/cm2 can be improved to a JSC of 39.12 mA/cm2 after adding the patterned polymer, mitigating shading losses almost completely. Furthermore, we investigate the performance of this layer with respect to varying angles of incidence and find that as long as the V-grooves are parallel to the line that describes the motion of the sun across the hemisphere, there is no loss in performance as a function of angle. In fact, based on the electronic and optical angular performance of the designed structure, we obtain an effective shading of 0.6% for a solar cell with 25% front metal grid coverage at 1000 suns, for a realistic concentration geometry. Lastly, we plan on presenting experimental IV-data of highly efficient III-V cells with V-grooves under concentration.
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