Impact of Cation Multiplicity on Halide Perovskite Defect Densities and Solar Cell Voltages

Martin Ledinský, Aleš Vlk, Tereza Schönfeldová, Jakub Holovský, Erkan Aydin, Hoang X. Dang, Zdeňka Hájková, Lucie Landová, Jan Valenta, Antonín Fejfar, Stefaan De Wolf

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17 Scopus citations


Metal-halide perovskites feature very low deep-defect densities, thereby enabling high operating voltages at the solar cell level. Here, by precise extraction of their absorption spectra, we find that the low deep-defect density is unaffected when cations such as Cs+ and Rb+ are added during the perovskite synthesis. By comparing single crystals and polycrystalline thin films of methylammonium lead iodide/bromide, we find these defects to be predominantly localized at surfaces and grain boundaries. Furthermore, generally, for the most important photovoltaic materials, we demonstrate a strong correlation between their Urbach energy and open-circuit voltage deficiency at the solar cell level. Through external quantum yield photoluminescence efficiency measurements, we explain these results as a consequence of nonradiative open-circuit voltage losses in the solar cell. Finally, we define practical power conversion efficiency limits of solar cells by taking into account the Urbach energy.
Original languageEnglish (US)
JournalThe Journal of Physical Chemistry C
StatePublished - Dec 8 2020


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