  In developing photovoltaic devices with high efficiencies, quantitative
determination of the carrier loss is crucial. In conventional solar-cell
characterization techniques, however, photocurrent reduction originating from
parasitic light absorption and carrier recombination within the light absorber
cannot be assessed easily. Here, we develop a general analysis scheme in which
the optical and recombination losses in submicron-textured solar cells are
evaluated systematically from external quantum efficiency (EQE) spectra. In
this method, the optical absorption in solar cells is first deduced by imposing
the anti-reflection condition in the calculation of the absorptance spectrum,
and the carrier extraction from the light absorber layer is then modeled by
considering a carrier collection length from the absorber interface. Our
analysis method is appropriate for a wide variety of photovoltaic devices,
including kesterite solar cells [Cu2ZnSnSe4, Cu2ZnSnS4, and Cu2ZnSn(S,Se)4],
zincblende CdTe solar cells, and hybrid perovskite (CH3NH3PbI3) solar cells,
and provides excellent fitting to numerous EQE spectra reported earlier. Based
on the results obtained from our EQE analyses, we discuss the effects of
parasitic absorption and carrier recombination in different types of solar
cells.
