4 research outputs found
Fluoride Chemistry in Tin Halide Perovskites
Tin is the frontrunner for substituting toxic lead in perovskite solar cells. However, tin suffers the detrimental oxidation of SnII to SnIV. Most of reported strategies employ SnF2 in the perovskite precursor solution to prevent SnIV formation. Nevertheless, the working mechanism of this additive remains debated. To further elucidate it, we investigate the fluoride chemistry in tin halide perovskites by complementary analytical tools. NMR analysis of the precursor solution discloses a strong preferential affinity of fluoride anions for SnIV over SnII, selectively complexing it as SnF4. Hard X-ray photoelectron spectroscopy on films shows the lower tendency of SnF4 than SnI4 to get included in the perovskite structure, hence preventing the inclusion of SnIV in the film. Finally, small-angle X-ray scattering reveals the strong influence of fluoride on the colloidal chemistry of precursor dispersions, directly affecting perovskite crystallization
Fluoridchemie in ZinnâHalogenidâPerowskiten
Zinn ist der Top-Favorit fĂŒr den Ersatz von giftigem Blei in Perowskit-Solarzellen. Allerdings kommt es dabei verstĂ€rkt zu der unerwĂŒnschten Oxidation von SnII zu SnIV. Die herkömmlichen Verfahren verwenden SnF2 in der Perowskit-VorlĂ€uferlösung, um die Bildung von SnIV zu verhindern. Dennoch bleibt der Wirkmechanismus des Additivs unklar. Um diesen eingehender zu erlĂ€utern, untersuchen wir die Fluoridchemie in Zinn-Halogenid-Perowskiten mit einander ergĂ€nzenden Analyseverfahren. NMR-Spektroskopie der VorlĂ€uferlösung offenbart eine stark bevorzugte AffinitĂ€t der Fluoridanionen fĂŒr SnIV gegenĂŒber SnII, wodurch dieses selektiv als SnF4 komplexiert wird. Harte Röntgenphotoelektronenspektroskopie an DĂŒnnschichten zeigt die geringere Bereitschaft von SnF4 gegenĂŒber SnI4, in die Perowskit-Struktur eingebaut zu werden und verhindert somit den Einschluss von SnIV in der DĂŒnnschicht. AbschlieĂend offenbart Röntgen-Kleinwinkelstreuung den starken Einfluss vom Fluorid auf die kolloidale Chemie der VorlĂ€uferlösungen, der sich direkt auf die darauffolgende Kristallisation auswirkt.European Research Council (ERC)Peer Reviewe
Interface defect formation for atomic layer deposition of SnO2 on metal halide perovskites
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Unveiling the Potential of Ambient Air Annealing for Highly Efficient Inorganic CsPbI3 Perovskite Solar Cells
Iqbal Z, FĂ©lix R, Musiienko A, et al. Unveiling the Potential of Ambient Air Annealing for Highly Efficient Inorganic CsPbI3 Perovskite Solar Cells. Journal of the American Chemical Society. 2024.Here, we report a detailed surface analysis of dry- and ambient air-annealed CsPbI3 films and their subsequent modified interfaces in perovskite solar cells. We revealed that annealing in ambient air does not adversely affect the optoelectronic properties of the semiconducting film; instead, ambient air-annealed samples undergo a surface modification, causing an enhancement of band bending, as determined by hard X-ray photoelectron spectroscopy measurements. We observe interface charge carrier dynamics changes, improving the charge carrier extraction in CsPbI3 perovskite solar cells. Optical spectroscopic measurements show that trap state density is decreased due to ambient air annealing. As a result, air-annealed CsPbI3-based n-i-p structure devices achieved a 19.8% power conversion efficiency with a 1.23 V open circuit voltage