Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 45: Hybrid Perovskite and Photovoltaics I (joint session CPP/HL)

HL 45.3: Talk

Wednesday, March 18, 2020, 10:00–10:15, ZEU 260

Unraveling origin of performance instability in mixed perovskite solar cells — •Małgorzata Kot¹, Chittaranjan Das², Tim Hellmann², Carolin Wittich², Iwan Zimmermann³, Mohammad Khaja Nazeeruddin³, Wolfram Jaegermann², and Jan Ingo Flege¹ — ¹BTU Cottbus-Senftenberg, Germany — ²TU Darmstadt, Germany — ³EPFL Lausanne, Switzerland

A degradation mechanism of mixed perovskite solar cells is mostly attributed to the segregation of halide phases in the perovskite film. However, our studies have revealed, that the mixed perovskites degrade due to the migration of iodine and methylammonium ions across the solar cell. Nonetheless, an ultrathin RT-ALD-Al₂O₃ layer deposited on top of perovskite can very effectively limit this migration thanks to the reactive property of this interface.[1-3] Namely, there is a closed cycle of the charge transfer between ALD and perovskite films. Such ALD film doesn’t cause any drastic changes in the perovskite morphology, chemical composition, optoelectronic properties or crystallinity. What more, it helps to preserve the initial properties of the film during exposure to the light and ambient air under real operating conditions and thus improves the stability of the solar cells. This ultra-thin Al₂O₃ layer prepared in an unusual RT process for ALD method significantly increases the lifetime of perovskite solar cells at a very low cost bringing thus the introduction of the perovskite solar cells into mass production. [1] M. Kot et al., ChemSusChem 11 (2018) 3640. [2] M. Kot et al., Energy Technol. 7 (2019) 1900975. [3] D. Schmeißer et al., J. Phys. Chem. C 123 (2019) 23352.