substrate (7 Ω sq–1) was purchased from Ruilong.
Cesium chloride (CsCl, 99.99%), lead iodide (PbI2, 99.9985%),
cesium iodide (CsI, 99.9%), nickel(II) nitrate (99.9985%), ethylenediamine
(99%), ethylene glycol (99%), and bathocuproin (BCP, 99.7%) were purchased
from Alfa Aesar. Methylammonium chloride (MACl, 99%) was purchased
from Thermo Scientific. Formamidinium iodide (FAI, >99.5%) was
purchased
from Lumtec. Butane-1,4-diammonium iodide (BDAI2, 98%),
dimethyl sulfoxide (DMSO, 99.5%), N,N-dimethylformamide (DMF, 99.5%), and fullerene (C60, 99.95%)
were purchased from Uni-Onward.