Mechanochemical Synthesis of Sn(II) and Sn(IV) Iodide Perovskites and Study of Their Structural, Chemical, Thermal, Optical, and Electrical Properties

Abstract

Phase‐pure CsSnI3, FASnI3, Cs(PbSn)I3, FA(PbSn)I3 perovskites (FA = formamidinium = HC(NH2)2+) as well as the analogous so‐called vacancy‐ordered double perovskites Cs2SnI6 and FA2SnI6 are mechanochemically synthesized. The addition of SnF2 is found to be crucial for the synthesis of Cs‐containing perovskites but unnecessary for hybrid ones. All compounds show an absorption onset in the near‐infrared (NIR) region, which makes them especially relevant for photovoltaic applications. The addition of Pb(II) and SnF2 is crucial to improve the electronic properties in 3D Sn(II)‐based perovskites, in particular their charge carriers mobility (≈0.2 cm2 Vs−1) which is enhanced upon reduction of the dark carrier conductivity. Stokes‐shifted photoluminescence is observed on dry powders of Sn(II)‐based perovskites, which makes these materials promising for light‐emitting and sensing applications. Thermal stability of all compounds is examined, revealing no significant degradation up to at least 200 °C. This meets the requirements for standard operation conditions of most optoelectronic devices and is potentially compatible with thermal vacuum deposition of polycrystalline thin films.

Making by Grinding: Mechanochemistry Boosts the Development of Halide Perovskites and Other Multinary Metal Halides

“…While most halide perovskites use Pb(II) as unique B‐cation, the partial or total replacement of Pb(II) by Sn(II) has also been investigated by MCS . Saski et al reported pure‐tin mixed‐halide perovskites ASn(Br:I) 3  with good phase purity under inert atmosphere .…”

Oriented Perovskite Crystal towards Efficient Charge Transport in FASnI3 Perovskite Solar Cells

“…We notice that the 36 h storage of the FASnI 3 film leads to the total degradation of perovskite without SnI 4 or FA 2 SnI 6 characteristic peaks being observed. [ 67,68 ] The improved film stability originates from dense and smooth high‐quality perovskite films with a lower Sn 4+ content with 2,3‐DAPAC treatment, and it is also related to slightly decreased hydrophilicity (Figure S7, Supporting Information). Finally, we compare the PCE and lifetime of our champion PSC with the recently reported passivation works using FASnI 3 as the light absorber.…”

Recent Advances and Perspectives on Powder‐Based Halide Perovskite Film Processing

“…[ 31–33 ] By the addition of appropriate organic molecules, it is possible to synthesize perovskite nanocrystals. [ 34 ] Furthermore, the mechanochemical synthesis of lead‐free perovskites based on tin, [ 16,35,36 ] copper, [ 37 ] or bismuth [ 38 ] on the B position was demonstrated as well. Mechanochemistry is a solvent‐free synthesis method.…”