Spiro ometad

60 mM Spiro-OMeTAD (Xi'an Polymer Light Technology Corp., ≥99.8%) solution was obtained by dissolving 72.3 mg Spiro-OMeTAD, 28.8 μL TBP and 17.5 μL LiTFSI stock solution (520 mg mL⁻¹ in acetonitrile) into 1 mL of chlorobenzene. FeCl₃ (Alfa Aesar, 98%) solution (100 mg mL⁻¹ in acetonitrile) was added into Spiro-OMeTAD solution to achieve the desired doping concentration. The hole transporting layer was deposited atop perovskite substrate through spin coating above mentioned solutions at 6000 rpm for 30 s. Finally, a 80 nm-thick Au top electrode was thermally evaporated onto substrates. For FK209 doping device, the film was deposited by spin coating the mixed solution of 68.6 μL FK209 solution (300 mg mL⁻¹ in acetonitrile) and 1 mL Spiro-OMeTAD solution.

N,N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), IPA, and SnO₂ colloid precursor are from Alfa Aesar. Spiro-OMeTAD, acetonitrile (ACN), bis(trifluoromethanesulfonyl)imide lithium (Li-TFSI), tert-butylpyridine (tBP), CsI, p-PBA, and m-PBA were purchased from Sigma-Aldrich. PbI₂ was purchased from Tokyo Chemical Industry. 3-Phenyl-2-propenammonium iodine (PPEAI), methylammonium chloride (MACl), methylammonium bromide (MABr), and formamidinium iodide (FAI) were synthesized as previously reported (52 ). Tris(2-(1H-pyrazol-1-yl)-4-tertbutylpyridine)-cobalt(III) tris(bis(trifluoromethylsulfonyl)imide) (FK209) was purchased from Xi’an Polymer Light Technology Corp. Chlorobenzene (CB) was obtained from Arcros. All reagents were purchased from commercial vendors and used as received.