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

Jakub Holovský, Katarína Ridzoňová, Amalraj Peter Amalathas, Brianna Conrad, Rupendra Kumar Sharma, Xin Yu Chin, Ebin Bastola, Khagendra Bhandari, Randy J. Ellingson, Stefaan De Wolf

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


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 the impact of deep defects is ignored by exponential extrapolation of the Urbach absorption edge, our loss analysis considers the full EQE including states below the Urbach edge and uses corrections for band-filling and light-trapping. We validate this new metric on a whole range of photovoltaic materials and verify its accuracy by electrical simulations. Any deviations between the new metric and experimental open-circuit voltage are due to the presence of spatially localized defects and are explained as violations of the assumption of flat quasi-Fermi levels through the device.
Original languageEnglish (US)
Pages (from-to)3221-3227
Number of pages7
JournalACS Energy Letters
StatePublished - Jul 3 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-07-07
Acknowledgements: This work was supported by Czech Ministry of Education, Youth and Sports grant no. CZ. 02.1.01/0.0/0.0/15_003/0000464 – “Centre of Advanced Photovoltaics” and Czech Science Foundation grant number no. 23-06285S. E.B., K.B., and R.J.E. acknowledge support from the Air Force Research Laboratory under agreement number FA9453-18-2-0037. We acknowledge here also a fruitful discussion with Thomas Kirchartz.


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