suppliers
without further purification. Tin dioxide(IV) and 15% hydrocolloid
dispersion (SnO2) were purchased from Alfa Aesar. Nickel(II)
acetate tetrahydrate (Ni(OCOCH3)2·4H2O, 99.995% trace metals basis), PbI2, spiro-OMeTAD
(purity ≥99.8%), sodium dodecylbenzene sulfonate (SDBS), isopropanol
(IPA), N,N-dimethylformamide (DMF),
dimethyl sulfoxide (DMSO), chlorobenzene (CB), acetonitrile (ACN),
4-tert-butylpyridine (tBP), lithium bis(trifluoromethane
sulfonyl)imide (Li-TFSI), and FK 209 Co(III) TFSI salts were from
Sigma-Aldrich. Formamidinium iodide (FAI), methylammonium chloride
(MACl), and methylammonium bromide (MABr) were obtained from GreatCell
Solar.