Below the Urbach Edge: Solar Cell Loss Analysis Based on Full External Quantum Efficiency Spectra

We suggest a new solar cell loss analysis using the external quantum efficiency (EQE) measured with sufficiently high sensitivity to also account for defects. Unlike common radiative-limit methods, where impact of deep defects is ignored by exponential extrapolation Urbach absorption edge, our considers full EQE including states below edge and uses corrections band-filling light-trapping. validate this metric on whole range photovoltaic materials verify its accuracy electrical simulations. Any deviations between experimental open-circuit voltage are due presence spatially localized explained as violations assumption flat quasi-Fermi levels through device.