Bis trifluoromethylsulfonyl amine lithium salt

Solubility tests were conducted by dissolving a few milligrams of Li-BL in N-methyl-2-pyrrolidone (Sigma Aldrich), de-ionized water, a mixture of ethylene carbonate (Sigma Aldrich): dimethyl carbonate (Sigma Aldrich) 1 : 1 v/v, dioxolane (Sigma Aldrich), dimethoxymethane (Sigma Aldrich) and tetraethylene glycol dimethyl ether (Sigma Aldrich). Electrochemical measurements were conducted using CR2032-type coin cells (MTI) with quartz membrane (Whatman) as a separator. The electrolyte was prepared by mixing bis(trifluoromethylsulfonyl) amine lithium salt (Sigma Aldrich) in tetraethylene glycol dimethyl ether (TEGDME). Fabrication of coin cells was conducted in an argon-filled glove box. Cyclic voltammetry and electrochemical impedance spectroscopy were measured with an Autolab PGSTAT 302 N potentiostat. Galvanostatic charge–discharge tests were performed on LAND CT2001A battery tester and on an Arbin Instruments BT-2000 battery cycler.

SnO₂ -ETL was fabricated with the SnO₂ colloid precursor (tin (IV) oxide, 15% in H₂O colloidal dispersion) purchased from Alfa Aesar. For the fabrication of the PSCs, formamidinium iodide (>99.99%) and methylammonium bromide (>99.99%) were purchased from Greatcell Solar. Lead bromide (PbBr₂, >98%) and lead (II) iodide (PbI₂, 99.99%) were obtained from TCI chemicals. Bis(trifluoromethylsulfonyl)amine lithium salt (Li-TFSI, 99.95%), methylammonium chloride (MACl, >98%), dimethyl sulfoxide (DMSO, 99.9% anhydrous), dimethylformamide (DMF, 99.8%), hexane (>98%), ethyl acetate (>99%), 4-tertbutylpyridine (t-BP, 98%), iodine (≥99.99%) and copper (99.999%) were obtained from Sigma-Aldrich and used without any purification. 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene, (Spiro-OMeTAD, >99%) for the deposition of the hole-transport layer (HTL) was obtained from Lumtech. Polydimethylsiloxane (PDMS) (Sylgard 184, Dow) was used for the PDMS stamp fabrication.