Tdmasn

ALD SnO₂ is deposited on top of the perovskite
at 10^–5 mbar in a homebuilt reactor, with specifications
discussed in a previous publication.^{13 (link),14 (link)} The metal–organic
precursor used for the deposition of the SnO₂ films is
tetrakis(dimethylamido)-Sn(IV), TDMA-Sn, 99.9%, from STREM Chemicals,
which is kept at 50 °C. As a co-reactant, water is used. Both
the precursor and co-reactant are supplied to the ALD chamber in a
vapor-drawn mode. The ALD cycle, carried out at 100 °C, consists
of a 500 ms TDMA-Sn dose, followed by a purge step of 15 s, then an
H₂O vapor dose of 25 ms, followed by a purge step of 15
s. The selected dosing and purge times correspond to self-limiting
conditions for the ALD process. The thickness, and refractive index,
of the ALD SnO₂ layers, grown on the c-Si substrate, is
determined by means of spectroscopic ellipsometry (SE) using a Cauchy
model in the region between 1.2 and 2.7 eV. The SE used is a J.A.
Woollam, Inc. M2000 UV ellipsometer, and the measured growth per cycle
is 0.11 (±0.01) nm.

The atomic layer deposition of SnO₂ was carried out in a Savannah 100 instrument (Cambridge Nanotech Inc.). Tetrakis(dimethylamino)-tin(IV) (TDMASn, 99.99% Sn, Strem Chemicals) was used as the precursor of Sn and DI water was used as the oxidizing agent, respectively. N₂ (99.9999%, Carbagas) was used as the carrier gas with a flow rate of 5 cm³ min^–1. The temperature of TDMASn precursor and deposition chamber were respectively held at 60 °C and 110 °C during each deposition. Each cycle of SnO₂ deposition includes following steps: (a) pulsing TDMASn for 30 s, equilibrating for 15 s and purging for 60 s, (b) evacuating followed by pulsing DI water for 1 s, equilibrating for 15 s before purging for 20 s. This cycle was repeated for the desired number for preparing SnO_{2 ALD} overlayer with different thickness.

Lead iodide (PbI₂, TCI, 99.99%), lead bromide (PbBr₂, TCI), formamidinium iodide (FAI, GreatCell Solar), formamidinium bromide (FAI, GreatCell Solar), methylammonium chloride (MACl, Dyenamo), cesium iodide (CsI, Alfa Aesar), cesium bromide (CsBr, Alfa Aesar), [2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz, TCI), fullerene (C₆₀, Sigma Aldrich, 99.5%), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, Lumescence Technology), lithium fluoride (LiF, Luminescence Technology), magnesium fluoride (MgF₂, Sigma Aldrich), dimethylformamide (DMF, Sigma Aldrich, anhydrous, 99.8%), dimethyl sulfoxide (DMSO, Sigma Aldrich, anhydrous, ≥99.9%), ethyl ethanoate (EA, Sigma Aldrich, anhydrous, 99.8%), ethanol (VWR Chemicals, absolute, 99.8%), tetrakis(dimethylamino)tin(iv) (TDMASn, 99.99%-Sn, Strem Chemicals), indium tin oxide (ITO) or indium zinc oxide (IZO), hydrogen-doped indium oxide (IOH) (using InO/ZnO target, Kurt J. Lesker Company, 90/10 wt%, 99.99%), nickel oxide (NiO_x) (using NiO_x target, Kurt J. Lesker Company, 99.995%).