Bismuth iodide

Bismuth iodide (BiI₃), bismuth
bromide (BiBr₃), copper iodide (CuI), titanium diisopropoxide
bis(acetylacetonate) (TDBA, 75 wt % in isopropanol), dimethylsulfoxide
(DMSO), hydroiodic acid (HI, 57%), chlorobenzene (CB, extra dry, 99.8%),
acetonitrile (99.9%), 4-tert-butylpyridine (4-tBP),
and bis(trifluoromethane)sulfonimide lithium salt (LiTFSI, 99.95%)
were purchased from Sigma-Aldrich. Tris[2-(1H-pyrazol-1-yl)-4-tert-butylpyridine]cobalt(III)tri[bis(trifluoromethane)sulfonimide]
(FK209 Co(III), >98%) was purchased from Dyenamo. Dimethylformamide
(DMF), silver iodide (AgI), and toluene were purchased from Alfa Aesar.
2,2′,7,7′-Tetrakis(N,N-di-p-methoxy phenylamino)-9,9-spirobifluorene (Spiro-OMeTAD)
was purchased from Lumtec. Fluorine-doped tin(IV) oxide (FTO)-coated
glass substrates of 2 cm × 2 cm were purchased from Yingkou Opv
Tech New Energy Technology Co.

Bismuth iodide (BiI_3, 99%), 4-tert-butylpyridine (TBP), tris (2-(1H-pyrazol-1-yl)-4-tert-butylpyridine-cobalt (III)Tris(bis(trifluoromethylsulfonyl)imide)) (FK 209), Bis(tri-fluoromethane) sulfonimide lithium salt (99.95%, Li-TFSI, trace metals basis), and chlorobenzene (99.8%, anhydrous) were obtained from Sigma Aldrich (St. Louis, MO, USA). Acetylacetone (C₅H₈O₂, 99.0%) and Tetra-isopropyl orthotitanate (C₁₂H₂₈O₄Ti, s.g 0.97) were from TCI (Tokyo, Japan). Acetonitrile, Ti0₂ paste 30NR-D, and cobalt (III)tris(trifluoromethylsulfonyl)imide) were from Greatcell solar materials (Queanbeyan, NSW, Australia). Cesium iodide (CsI, 99.99%) was obtained from Acros (Geel, Belgium), while ethanol absolute (99.9%) was from Innochem (Pyeongtaek, Republic of Korea). Isopropanol, methanol, dimethyl sulphoxide (DMSO, anhydrous, ≥99.9%), and N, N-dimethylformamide (DMF, anhydrous, 99.8%) were obtained from Alfer Asar (Ward Hill, MA, USA). 2,2,7,7-Tetrakis (N, N-p-dimethoxyphenylamino)-9,9-spirobifluorene (spiro-OMeTAD) Spiro OMeTAD was from Xi’an Polymer Light Technology Corp (Xi’an, China). All chemicals and reagents were used without further purification.