Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 43: Perovskite and Hybrid Photovolatics II (joint session HL/CPP)
HL 43.3: Talk
Thursday, April 4, 2019, 15:30–15:45, H36
Reversible Bandgap Instabilities in Multiple-Cation Mixed-Halide Perovskite Solar Cells — •Fabian Ruf1, Pascal Rietz1, Meltem F. Aygüler2, Pablo Docampo3, Heinz Kalt1, and Michael Hetterich1,4 — 1Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Department of Chemistry and CeNS, University of Munich (LMU), 81377 München, Germany — 3Physics Department, School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom — 4Light Technology Institute, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
Multiple-cation mixed-halide perovskites have demonstrated their great potential as promising candidates for next-generation thin-film photovoltaics due to further improved power-conversion efficiency and stability. In this contribution, we investigate the stability of the compositional and resulting electronic structure of Cs0.05(FA0.83 MA0.17)0.95Pb(I0.83Br0.17)3 solar cell absorbers using electroreflectance (ER) spectroscopy as sensitive and non-invasive measurement technique. Despite the enhanced compositional stability, these compounds show a decrease of the bandgap up to 70 meV under AM1.5 illumination and applied voltage. We attribute this to segregation of the intermixed perovskite into iodide-rich and bromide-rich domains which is also confirmed by in-situ X-ray diffraction. A detailed study under operation-relevant conditions (illumination and bias) is conducted in various environments (different oxygen contents and relative humidity) to evaluate the consequences for photovoltaic applications.