Starting materials: PbI2, toluene, butyric acid, butylamine, formamidinium acetate
Product: Powder film on glass substrate
Description: PbI2, toluene, butyric acid, and butylamine were mixed in a capped flask. Separately, formamidinium acetate was dissolved in toluene and butyric acid. The solutions are combined and stirred until a red solid precipitated. The solid was removed by centrifuging at 6000 rpm for 3 minutes. It was then re-dispersed in hexane and centrifuged again to obtain the final paintlike paste. The paintlike paste was then deposited on a glass substrate. A Pasteur pipette was used to spread the paste over the surface and was then allowed to dry.
Method: Diffuse Reflectance Spectra
Description: Diffuse reflectance spectra were measured in a Shimadzu UV 2450 instrument. A Ba2SO4 powder palette was the reference used.
Starting materials: PbI2, toluene, butyric acid, butylamine, formamidinium acetate, anhydrous acetonitrile
Product: Thin film on glass substrate
Description: PbI2, toluene, butyric acid, and butylamine were mixed in a capped flask. Separately, formamidinium acetate was dissolved in toluene and butyric acid. The solutions are combined and stirred until a red solid precipitated. The solid was removed by centrifuging at 6000 rpm for 3 minutes. It was then re-dispersed in hexane and centrifuged again to obtain the final paintlike paste. The solid material was dissolved in acetonitrile to a desired concentration and then was spin-coated onto a glass substrate at 3000 rpm for 30 seconds.
Method: UV-vis absorption
Description: An Agilent Carry 60 UV-vis instrument was used in transmission mode to measure the absorbance. A blank glass substrate was used as the baseline.
Starting materials: PbO (99.9%), FA acetate, hydroiodic acid (HI, 57 wt % in H2O, distilled, stabilized, 99.95%), butylamine, hypophosphorous acid solution (H3PO2, 50 wt % in H2O)
Product: red plate-shaped crystals
Description: First, PbO (223 mg, 1 mmol) and FA acetate (52.1 mg, 0.5 mmol) were added to 1.5 mL of concentrated HI solution. These substances were dissolved under constant stirring and heating. Then, BA (89.1 μL, 0.9 mmol) was added to 0.25 mL of concentrated aqueous H3PO2 in a separate vial. This solution was stirred and was soon added to the initial solution. The temperature was lowered to 125º C until crystals began to form. The temperature was lowered again to 80ºC, the hot plate was turned off after 60 minutes, and after 30 minutes thereafter, the crystals were collected.
Method: UV-vis absorption
Description: A Shimadzu UV-3600 UV-vis NIR spectrometer was used. BaSO4 was used as a reference of 100% reflectance for all measurements.