Origin of Sn(ii) oxidation in tin halide perovskites

Abstract

<p>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)...</p>

Fluoride Chemistry in Tin Halide Perovskites

“…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.…”

“…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.…”

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

“…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.…”

Fluoridchemie in Zinn‐Halogenid‐Perowskiten

“…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.…”