Ambient-air-stable inorganic Cs2SnI6 double perovskite thin films via aerosol-assisted chemical vapour depositionElectronic supplementary information (ESI) available. See DOI: 10.1039/c8ta03133a
Air-stable caesium tin iodide double perovskite (Cs 2 SnI 6 ) thin films have been fabricated via aerosol-assisted chemical vapour deposition (AACVD). We compare the properties of the double perovskite films made using AACVD with those made by the widely used spin-coating method. Films with purer cr...
Saved in:
Main Authors | , , , , , , |
---|---|
Format | Journal Article |
Language | English |
Published |
19.06.2018
|
Online Access | Get full text |
Cover
Loading…
Summary: | Air-stable caesium tin iodide double perovskite (Cs
2
SnI
6
) thin films have been fabricated
via
aerosol-assisted chemical vapour deposition (AACVD). We compare the properties of the double perovskite films made using AACVD with those made by the widely used spin-coating method. Films with purer crystalline phase (less CsI impurity) and far better stability in ambient air can be obtained by AACVD compared with spin coating. The AACVD-grown Cs
2
SnI
6
films retain high phase purity for at least ∼100 days aging in air with negligible CsI impurities detected over this time, as determined by X-ray diffraction. The films exhibit an optical band gap energy (
E
g
) of
ca.
1.3 eV and a homogeneous morphology with the expected nominal stoichiometry within error, as probed by energy-dispersive X-ray spectroscopy. Overall, the characteristics of the Cs
2
SnI
6
films are highly process-dependent,
e.g.
they are influenced by the presence of hydroiodic acid (HI) in the precursor solution. Without HI addition, an iodine-deficient film with more CsI is produced, which also exhibits a larger
E
g
of
ca.
1.6 eV. In addition to bulk properties, we utilise X-ray photoelectron spectroscopy (XPS) to scrutinise the surface characteristics in detail. We find excess Sn and I located at the surfaces. This can be attributed to the presence of SnI
4
from the deposition precursor vapour. Furthermore, following aging in air, an increase in CsI impurity for the AACVD (+HI)-grown film is observed, along with a reduction in SnI
4
at the surfaces. Near-ambient pressure XPS (NAP-XPS) is used to examine the surface stability of AACVD (+HI)-grown films on exposure to O
2
and H
2
O. No enhancement in the amount of CsI impurity is observed after both H
2
O vapour (9 mbar) and O
2
(5 mbar) exposure. Nevertheless, the concentrations of tin and iodine change after exposure, suggesting that SnI
4
protects Cs
2
SnI
6
from degradation. This passivation effect of SnI
4
on Cs
2
SnI
6
surfaces is proposed to explain the additional stability of Cs
2
SnI
6
fabricated
via
AACVD.
Air-stable caesium tin iodide double perovskite (Cs
2
SnI
6
) thin films have been fabricated
via
aerosol-assisted chemical vapour deposition (AACVD). |
---|---|
Bibliography: | 10.1039/c8ta03133a Electronic supplementary information (ESI) available. See DOI |
ISSN: | 2050-7488 2050-7496 |
DOI: | 10.1039/c8ta03133a |