Crystal system: orthorhombic
| Photoluminescence peak position, nm |
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Starting materials: PbI2, HI, C4H9NH2
Product: Orange-yellow sheetlike crystals
Description: Grow the crystals under slowly-cooled aqueous hydriodic acid solutions. Perform all synthetic steps and crystal manipulations after synthesis in an inert atmosphere to prevent oxidation. Dissolve 0.534 g (1.16 mmol) of PbI2 in 2 mL of concentrated (57 wt %) aqueous HI solvent under flowing argon at 90 °C. In a separate tube, dissolve 2.32 mmol of (C4H9NH2).HI in 3 mL of concentrated HI solution and add to the metal halide solution. Ramp the solution temperature at 2 °C/h from 90 to -10 °C, filter the crystals formed under argon or nitrogen and dry in argon at 80 °C.
Method: Photoluminescence
Description: Collect the photoluminescence spectra within several hours after the crystals were synthesized, and maintain the samples in an argon-filled cell during measurement to prevent degradation. The photoluminescence spectra were excited by 457.9 nm (2.71 eV) light from an argon ion laser. This light was strongly absorbed by each sample, ensuring that the observed luminescence came from the front side of the samples. The excitation density was below 1 W cm-2. Refer to Page 794 for details.
Crystal system: orthorhombic
| Photoluminescence peak position, nm |
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Starting materials: PbI2, toluene, butyric acid, butylamine, butylammonium iodide
Product: Powder film on glass substrate
Description: PbI2, butyric acid, toluene, and butylamine were mixed in a capped flask. Separately, butylammonium iodide was dissolved in toluene with butylamine and butyric acid. The two solutions were combined and stirred until an insoluble yellow solid precipitated. The solid was removed by centrifuging at 6000 rpm for 3 minutes. The yellow solid was redispersed in toluene and centrifuged a second time, to produce the final products. 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: Photoluminescence spectra
Description: A Horiba-Jobin Yvon Fluorolog-3 instrument was used on the powder films to measure photoluminescence spectra. Excitation was perpendicular to the sample and emission was collected at an angle of ~15 degrees. The data was corrected according to the lamp and detector details by using algorithms from the equipment software.