  Intermediate band solar cells (IBSCs) pursue the increase in efficiency by
absorbing below-bandgap energy photons while preserving the output voltage.
Experimental IBSCs based on quantum dots have already demonstrated that both
below-bandgap photon absorption and the output voltage preservation, are
possible. However, the experimental work has also revealed that the
below-bandgap absorption of light is weak and insufficient to boost the
efficiency of the solar cells. The objective of this work is to contribute to
the study of this absorption by manufacturing and characterizing a quantum dot
intermediate band solar cell with a single quantum dot layer with and without
light trapping elements. Using one-dimensional substrate texturing, our results
show a three-fold increase in the absorption of below bandgap energy photons in
the lowest energy region of the spectrum, a region not previously explored
using this approach. Furthermore, we also measure, at 9K, a distinguished split
of quasi-Fermi levels between the conduction and intermediate bands, which is a
necessary condition to preserve the output voltage of the cell.
