How the Deep Defects and Light Trapping Limit the Cell Voltage and How to Measure Them
Jakub Holovský a b, Branislav Dzurňák a, Meng-Hsueh Kuo a, Lucie Landová a b, Ivana Beshajová Pelikánová a, Neda Neykova a b
a Centre for Advanced Photovoltaics, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic, Technická, 2, Czech Republic
b Institute of Physics of the Czech Academy of Sciences, Czech Republic
Proceedings of Device Physics Characterization and Interpretation in Perovskite and Organic Materials (DEPERO)
VALÈNCIA, Spain, 2023 October 3rd - 5th
Organizers: Sandheep Ravishankar, Juan Bisquert and Evelyne Knapp
Invited Speaker, Jakub Holovský, presentation 011
Publication date: 14th September 2023

Recently we suggested a new solar cell loss analysis by using the absorptance or simple 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 this newly established 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 [1]. Newly, the reciprocity between photoluminescence and absorptance will be discussed and the method of experimental determination of light trapping correction factor will be introduced and experimentally validated on the perovskite layers deposited on substrates with different roughness.

The work was supported by the Czech Science Foundation grant no 23-06543S

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