Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 61: Perovskite and Hybrid Photovolatics II (joint session HL/CPP)

CPP 61.3: Vortrag

Donnerstag, 4. April 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 Hetterich^1,4 — 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 Cs_0.05(FA_0.83 MA_0.17)_0.95Pb(I_0.83Br_0.17)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.