Crystal system: unknown
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: CH3NH3I [from synthesis], SnI2 [from synthesis], distilled HI 57% aqueous (99.95%), H3PO2 (50% aqueous)
Product: Black MASnI3 crystals
Description: Charge 100 ml 2-necked round bottom flask with a mixture of aqueous HI (6.8 ml, 7.58M) and aqueous H3PO2 (1.7 ml, 9.14M). The liquid was degassed by passing a stream of nitrogen through it for 1 min and keeping it under a nitrogen atmosphere throughout the experiment. Dissolve SnI2 (372 mg, 1 mmol) in the mixture upon heating the flask to 120 °C using an oil bath, under constant magnetic stirring, forming a bright yellow solution. Add solid CH3NH3I (159 mg, 1 mmol). Evaporate solution to approximately half its original volume by heating at 120 °C. Discontinue stirring and leave the solution to cool back to room temperature. Upon cooling, black, elongated, rhombic dodecahedral (12 faces) crystals of the title compound were precipitated. Leave crystals to grow for a further 24 h under a nitrogen atmosphere before filtering and washing copiously with degassed EtOH. Yield 70-90%.
Method: Optical-diffuse reflectance
Description: Measurements were performed at room temperature using a Shimadzu UV-3101 PC double-beam, double-monochromator spectrophotometer operating from 200 to 2500 nm. BaSO4 was used as a nonabsorbing reflectance reference. The generated reflectance-versus-wavelength data were used to estimate the band gap of the material by converting reflectance to absorbance data according to the Kubelka−Munk equation: α/S =(1 − R)^2/2R, where R is the reflectance and α and S are the absorption and scattering coefficients, respectively. Refer to Page 9029 Figure 9.
Crystal system: tetragonal
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: CH3NH3I, SnI2
Product: Black MASnI3 Solid
Description: Load equimolar amounts of SnI2 and MAI in a 9mm pyrex tube. Shake materials mechanically to ensure a homogenous mixture. Place tube on a sealing line evacuated to 10-4 mbar and flame sealed. Immerse tube on a sand bath standing at 200 °C, such that the mixture of solids was heated homogeneously. Maintain 4/5 of the tube outside the bath at room temperature. Leave solids in the bath for 2 h to form a homogeneous black solid. The Sn containing solids are air sensitive. No obvious color changes are observed.
Method: Optical-diffuse reflectance
Description: Measurements were performed at room temperature using a Shimadzu UV-3101 PC double-beam, double-monochromator spectrophotometer operating from 200 to 2500 nm. BaSO4 was used as a nonabsorbing reflectance reference. The generated reflectance-versus-wavelength data were used to estimate the band gap of the material by converting reflectance to absorbance data according to the Kubelka−Munk equation. Refer to Page 9029 Figure 9.
Crystal system: unknown
| Band gap (optical, diffuse reflectance), K |
|---|
Starting materials: CH3NH3I, SnI2
Product: Black MASnI3 Ingot
Description: Load equimolar amounts of SnI2 and MAI in a 15mm pyrex test tube. Shake materials mechanically to ensure a homogenous mixture. Immerse in a sand bath standing at 350 °C under a gentle flow of nitrogen. The reaction proceeds within 0.5-1 min. The formation of a homogeneous black melt signals the end of the reaction. Upon melting the tube was removed from the bath and left to cool in air, usually producing a shiny black ingot.
Method: Optical-diffuse reflectance
Description: Measurements were performed at room temperature using a Shimadzu UV-3101 PC double-beam, double-monochromator spectrophotometer operating from 200 to 2500 nm. BaSO4 was used as a nonabsorbing reflectance reference. The generated reflectance-versus-wavelength data were used to estimate the band gap of the material by converting reflectance to absorbance data according to the Kubelka−Munk equation: α/S =(1 − R)^2/2R, where R is the reflectance and α and S are the absorption and scattering coefficients, respectively. Refer to Page 9029 Figure 9.
Crystal system: unknown
| Band gap (optical, diffuse reflectance), K |
|---|
Starting materials: CH3NH3I, SnI2
Product: Black MASnI3 Powder
Description: Place equimolar amounts of SnI2 and MAI in an agate mortar and ground carefully with a pestle until a visually homogeneous, black powder is obtained.
Method: Optical-diffuse reflectance
Description: Measurements were performed at room temperature using a Shimadzu UV-3101 PC double-beam, double-monochromator spectrophotometer operating from 200 to 2500 nm. BaSO4 was used as a nonabsorbing reflectance reference. The generated reflectance-versus-wavelength data were used to estimate the band gap of the material by converting reflectance to absorbance data according to the Kubelka−Munk equation: α/S =(1 − R)^2/2R, where R is the reflectance and α and S are the absorption and scattering coefficients, respectively. Refer to Page 9029 Figure 9.