Origin of Sn(<scp>ii</scp>) oxidation in tin halide perovskites

Pascual, Jorge; Nasti, Giuseppe; Aldamasy, Mahmoud H.; Smith, Joel A.; Flatken, Marion; Phung, Nga; Girolamo, Diego Di; Turren‐Cruz, Silver‐Hamill; Li, Meng; Dallmann, André; Avolio, Roberto; Abate, Antonio

doi:10.1039/d0ma00245c

Cited by 149 publications

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“…Following the same method, we added SnF 2 to a Sn IV ‐containing solution after being aged by heating at 100 °C for 3 h. Saidaminov et al. and we recently described that this thermal treatment promotes Sn II oxidation in DMSO solutions [7, 8] . The color of the aged solution goes from an intense red to a pale yellow to that of the fresh sample.…”

Section: Resultsmentioning

confidence: 99%

“…This affinity of fluorides towards Sn IV can have several important implications that may reduce Sn IV content in the final film. For instance, the strong preference for Sn IV means that fluorides could complex it as soon as it is generated, whether from O 2 in the environment or DMSO‐driven oxidation [7, 8, 11] . In fact, one should think if SnF 2 would be as valuable for other solvents as in DMSO, as fluorides could be critical in sequestrating Sn IV as soon as it is oxidized by this solvent, making it less harmful.…”

Section: Resultsmentioning

confidence: 99%

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Fluoride Chemistry in Tin Halide Perovskites

et al. 2021

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Fluoride Chemistry in Tin Halide Perovskites

et al. 2021

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“…Introducing tin into the perovskite lattice, however, can adversely affect the device performance [8][9][10] -primarily by self-doping due to the oxidation of Sn(II) to Sn(IV). This process readily occurs through reactions with the solvent 11,12 or trace oxygen 13,14 . Suppressing these oxidation processes is therefore the key to realizing high device performance.…”

Section: Introductionmentioning

confidence: 99%

Optimized Carrier Extraction at Interfaces for 23.6% Efficient Tin–Lead Perovskite Solar Cells

Otsuka

Murdey

et al. 2021

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Carrier extraction is a key issue which limits the efficiency of perovskite solar cells. In this work, carrier extraction is improved by modifying the perovskite layers with a combination of ethylenediammonium diiodide post-treatment and glycine hydrochloride additive. Ethylenediammonium dications primarily affect the top surface of the perovskite films, while glycinium cations preferentially accumulate at the bottom region. The top and bottom interface modifications improve the crystallinity of the perovskite films and lower the density of electrical traps via surface passivation effects, resulting in long charge carrier lifetimes. The orientated aggregation of the ethylenediammonium and glycinium cations at the charge collection interfaces result in the formation of surface dipoles, which facilitate charge extraction. The performance of the treated solar cell devices also increases. The fill factor rose to 0.82, and the power conversion efficiency reaches 23.6% (23.1% certified). The open circuit voltage reaches 0.91 V, just 0.06 V below the Shockley–Queisser limit. The unencapsulated devices also show improved stability under AM 1.5G, retaining over 80% of the initial efficiency after 200 h continuous operation in inert atmosphere. Our strategy is also successfully applied to centimeter-scale devices, with efficiencies up to 21.0%.

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“…Daher postulieren wir, dass SnF 2 an einer weiteren Art chemischen Reaktion beteiligt sein muss.I nf r ühen Stadien der Entwicklung von Zinn-Halogenid-Perowskiten dachte man, dass eine Gelbfärbung der Lçsung die Eliminierung von Sn IV durch dessen Reduktion mittels SnF 2 impliziert. [28] Anhand von NMR decken wir auf,dass zwischen Sn IV [7,8] Die Farbe der gealterten Lçsung geht von einem intensiven Rot zu einem blassen Gelb,wie auch bei der frischen Probe, über. Im Gegensatz zur frischen Lçsung wissen wir, dass jedoch ein gewisser Gehalt an Sn IV in der gealterten Lçsung vorhanden ist.…”

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Fluoridchemie in Zinn‐Halogenid‐Perowskiten

et al. 2021

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Zinn ist der Top-Favorit fürden Ersatz von giftigem Blei in Perowskit-Solarzellen. Allerdings kommt es dabei verstärkt zu der unerwünschten Oxidation von Sn II zu Sn IV .Die herkçmmlichen Verfahren verwenden SnF 2 in der Perowskit-Vorläuferlçsung,u md ie Bildung von Sn IV zu verhindern. Dennochb leibt der Wirkmechanismus des Additivs unklar. Um diesen eingehender zu erläutern, untersuchen wir die Fluoridchemie in Zinn-Halogenid-Perowskiten mit einander ergänzenden Analyseverfahren. NMR-Spektroskopie der Vorläuferlçsung offenbart eine stark bevorzugte Affinitätd er Fluoridanionen fürS n IV gegenüber Sn II ,w odurchd ieses selektiv als SnF 4 komplexiert wird.H arte Rçntgenphotoelektronenspektroskopie an Dünnschichten zeigt die geringere Bereitschaft von SnF 4 gegenüber SnI 4 ,i nd ie Perowskit-Struktur eingebaut zu werden und verhindert somit den Einschluss von Sn IV in der Dünnschicht. Abschließend offenbart Rçntgen-Kleinwinkelstreuung den starken Einfluss vom Fluorid auf die kolloidale Chemie der Vorläuferlçsungen, der sich direkt auf die darauffolgende Kristallisation auswirkt.

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Origin of Sn(ii) oxidation in tin halide perovskites

Abstract:
Tin-halide perovskites have great potential as photovoltaic materials, but their performance is hampered by undesirable oxidation of Sn(II) to Sn(IV). In this work, we use nuclear magnetic resonance spectroscopy (NMR)...

Cited by 149 publications

References 21 publications

Fluoride Chemistry in Tin Halide Perovskites

Fluoride Chemistry in Tin Halide Perovskites

Optimized Carrier Extraction at Interfaces for 23.6% Efficient Tin–Lead Perovskite Solar Cells

Fluoridchemie in Zinn‐Halogenid‐Perowskiten

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Origin of Sn(ii) oxidation in tin halide perovskites

Abstract: Tin-halide perovskites have great potential as photovoltaic materials, but their performance is hampered by undesirable oxidation of Sn(II) to Sn(IV). In this work, we use nuclear magnetic resonance spectroscopy (NMR)...

Cited by 149 publications

References 21 publications

Fluoride Chemistry in Tin Halide Perovskites

Fluoride Chemistry in Tin Halide Perovskites

Optimized Carrier Extraction at Interfaces for 23.6% Efficient Tin–Lead Perovskite Solar Cells

Fluoridchemie in Zinn‐Halogenid‐Perowskiten

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Abstract:
Tin-halide perovskites have great potential as photovoltaic materials, but their performance is hampered by undesirable oxidation of Sn(II) to Sn(IV). In this work, we use nuclear magnetic resonance spectroscopy (NMR)...