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Local Voltage Mapping of Solar Cells in the Presence of Localized Radiative Defects



Brianna Conrad, Behrang Hamadani


Hyperspectral electroluminescence and photoluminescence imaging of photovoltaic materials and devices produces three-dimensional spatially- and spectrally-resolved luminescence data which can be calibrated to an absolute scale, enabling the extraction of high resolution maps of quantities such as the local voltage or quasi-Fermi-level splitting. This extraction requires supplemental measurements of external quantum efficiency (EQE), but these do not have the same spatial resolution. Previously, assumptions have been made to overcome this limitation. In this work we evaluate these assumptions for the case of InGaAs solar cells containing small regions with elevated concentrations of radiative defects, and therefore significant spatial variation in the luminescence spectrum shape. Although appropriate for small variations in spectral shape, we nd that with more significant variation, these assumptions can result in non-physical EQEs and too-low voltages. Combining multiple methods can help alleviate this, or a minimum voltage map can be extracted, which will be similar to the actual voltage when EQE is high.
Applied Physics Letters


Electroluminescence, Photoluminescence, Hyperspectral Imaging, Photovoltaic Cells


Conrad, B. and Hamadani, B. (2022), Local Voltage Mapping of Solar Cells in the Presence of Localized Radiative Defects, Applied Physics Letters, [online],, (Accessed April 19, 2024)
Created July 18, 2022, Updated February 28, 2024