See all entries for this property (24 total)
Crystal system: orthorhombic
| a: | 7.9814 Å |
| b: | 11.8623 Å |
| c: | 8.5846 Å |
| α: | 90° |
| β: | 90° |
| γ: | 90° |
Starting materials: 1M solution of PbBr2 and CH3NH3Br in dimethylformamide (DMF)
Product: CH3 NH3 PbBr3 crystals
Description: 1M solution of PbBr2 and CH3NH3Br in DMF passed through 0.22 micron filter, filtered solution heated in oil bath to 82 degrees C, removed after 30 minutes. CH3 NH3 PbBr3 crystals form and are isolated quickly from the remaining liquid to avoid redissolution.
Method: Single crystal X-ray diffraction
Description: Performed using a Bruker D8 venture diffractometer with Photon 100 CMOS detector. Oxford Cryostream for temperature control. Mo K-alpha radiation (0.71703 Angstrom) was used. phi and omega angle scans were performed, frames integrated and absorption correction performed (implemented in Bruker APEX 3 software). Structure was solved using SHELXT software and refined (Olex 2 software package). Pb and Br thermal displacement parameters refined anisotropically; C, N, and H parameters are refined isotropically. The C-N bond length was constrained to 1.47 Angstroms.
Crystal system: unknown
| Exciton energy, eV |
|---|
Starting materials: MABr salt, PbBr2 salt, stoichiometric ratio 2:1
Product: spin-coated thin film
Description: Starting materials dissolved in 4:1 DMF:DMSO solvent mixture, stirred for 30 min at room temperature. Substrate: Quartz substrate with 120 nm gold layer with interdigitated fingers. Precursor solution (0.1-0.3 molar) pipetted onto substrate and spin-coated, 4000 rpm / 30 seconds, targeting film thicknesses 80-300 nm.
Method: Electroabsorption
Description: Films were spin-coated onto interdigitated Au electrode array - 45 micron distance between opposing fingers. Samples mounted in cryostat with Cu wires soldered to opposing electrode stripes. Xe lamp light spectrally filtered, focused on sample and subsequently on UV-enhanced Si photodiode detector. Sample transmission, substrate transmission, and sample electrotransmission were collected in independent scans. Absorbance and electroabsorbance were then calculated from the respective transmissions.
Comment: Significantly more detail in paper.
Crystal system: unknown
| Band gap (fundamental), eV |
|---|
Starting materials: MABr salt, PbBr2 salt, stoichiometric ratio 2:1
Product: spin-coated thin film
Description: Starting materials dissolved in 4:1 DMF:DMSO solvent mixture, stirred for 30 min at room temperature. Substrate: Quartz substrate with 120 nm gold layer with interdigitated fingers. Precursor solution (0.1-0.3 molar) pipetted onto substrate and spin-coated, 4000 rpm / 30 seconds, targeting film thicknesses 80-300 nm.
Method: Electroabsorption
Description: Films were spin-coated onto interdigitated Au electrode array - 45 micron distance between opposing fingers. Samples mounted in cryostat with Cu wires soldered to opposing electrode stripes. Xe lamp light spectrally filtered, focused on sample and subsequently on UV-enhanced Si photodiode detector. Sample transmission, substrate transmission, and sample electrotransmission were collected in independent scans.Absorbance and electroabsorbance were then calculated from the respective transmissions. The fundamental gap is determined by the crossover point of absorption curves measured under different electric fields in the fundamental band gap region.
Comment: Significantly more detail in paper.
Crystal system: unknown
| Exciton binding energy, eV |
|---|
Starting materials: MABr salt, PbBr2 salt, stoichiometric ratio 2:1
Product: spin-coated thin film
Description: Starting materials dissolved in 4:1 DMF:DMSO solvent mixture, stirred for 30 min at room temperature. Substrate: Quartz substrate with 120 nm gold layer with interdigitated fingers. Precursor solution (0.1-0.3 molar) pipetted onto substrate and spin-coated, 4000 rpm / 30 seconds, targeting film thicknesses 80-300 nm.
Method: Electroabsorption
Description: Films were spin-coated onto interdigitated Au electrode array - 45 micron distance between opposing fingers. Samples mounted in cryostat with Cu wires soldered to opposing electrode stripes. Xe lamp light spectrally filtered, focused on sample and subsequently on UV-enhanced Si photodiode detector. Sample transmission, substrate transmission, and sample electrotransmission were collected in independent scans. Absorbance and electroabsorbance were then calculated from the respective transmissions. The exciton binding energy arises as the difference of the 1s exciton peak energy observed in conventional absorption and the fundamental gap as determined by the crossover point of absorption curves measured under different electric fields in the fundamental band gap region.
Comment: Significantly more detail in paper.
Crystal system: cubic
| Band gap (optical, diffuse reflectance), eV |
|---|
Starting materials: Lead(II) acetate (Chemical Reagents, Sigma), concentrated aqueous HBr, CH3NH2 (40% soluble in water, Merck)
Product: MAPbBr3 single crystal ~0.1mm, bright red/orange
Description: Precipitate polycrystalline MAPbBr3 from a halogenated acid solution using the method of [1]. Dissolve 1.88 g of lead(II) acetate in 40 ml concentrated to 48 wt% HBr aqueous solution warmed (~90 °C) in a water bath. Then add another 2 ml of HBr solution with 0.45 g CH3NH2. Crystallize by cooling the solution from 90 °C to room temperature over 3 hours. Wash product with acetone and dry overnight at 100 °C in a vacuum oven. Obtain larger crystals via slow cooling from 90 to 50 °C over 3 days. Refer to Page 9299 Section 2.1 Synthesis; Figure 1.
Comment: Synthesis references: [1] A. Poglitsch and D. Weber, J. Chem. Phys., 1987, 87, 6373–6378. [2] Q. Xu, T. Eguchi, H. Nakayama, N. Nakamura and M. Kishita, Z. Naturforsch., A: Phys. Sci., 1991, 46, 240–246.
Method: UV-Vis absorption (diffuse reflectance)
Description: UV-Visible-NIR spectrophotometer (Shimadzu UV-3600) with integrating sphere attachment (ISR-3100) operating in the 300–1500 nm region. Highly refined barium sulfate powder (Wako, pure) was used as a reflectance standard. Optical absorption coefficient was determined according to the Kubelka–Munk equation. In this manner, optical band gaps for the perovskites were determined. Refer to Page 9300 Section 3.1 Paragraph 3; Figure 3,4.
Starting materials: MABr (0.53 M) , PbBr2 (0.4 M), OLA (625 μL) and OA (25 μL), (Toluene, 12.5 mL)
Product: MAPbBr3
Description: The 2D perovskite MAPbBr3 was synthesized from a solution containing MABr (0.53 M) and PbBr2 (0.4M), which was dissolved in a polar DMF solvent. This solution was then mixed with a non-polar Toluene solvent. As a result, a precipitate of MAPbBr3 was formed as nanoplatelets via crystallization.
Method: Photoluminescence Spectra
Description: A CCD spectrometer was used to obtain the absolute absorbance of the colloidal solution in the non-polar solvent of Toluene. The PL of the colloidal solutions were obtained using the Quantaurus QY (C11347-11) from Hamamatsu.
See all entries for this property (6 total)
| Initial crystal system | unknown |
| Final crystal system | cubic |
| Initial space group | Unknown |
| Final space group | Pm3m |
| Direction | Both |
| Phase transition temperature | 227.0 (±5.0) K |
Hysteresis: NIL
| Initial crystal system | unknown |
| Phase transition temperature | K |
Starting materials: HBr, CH3NH2, Pb(NO3)2
Product: Partially deuterated MAPbBr3
Description: Add concentrated HBr to neutralize 20 g of 40% CH3NH2 aqueous solution. Add 7.1 g (0.021 mol) of Pb(NO3)2 solution drop-wise under vigorous stirring at 100°C to the concentrated CH3NH2Br solution. Red organic crystals form while dripping in the solution. Cool the solution to room temperature and filter out the crystals. Wash crystals firstly with n-butanol and then with benzene; subsequently dry crystals in vacuum. Partially N-deuterated samples required for the NMR studies were prepared using D-containing solutions. Refer to Page 413 Experimental.
Comment: Synthesis references: [1] Canadian Journal of Chemistry, 1987, 65(5): 1042-1046 https://doi.org/10.1139/v87-176 [2] D. WEBER. Z. Naturforsch. 33b, 1443 (1978).
Method: 2H and 14N NMR
Description: Measurements were carried out at 8.48 T with a Nicolet 360NB spectrometer using a broad band (16-58 MHz) variable-temperature 10 mm probe supplied by Nicolet. The 2-H and 14-N frequencies were 55.427 and 26.083 MHz, respectively. Refer to Page 414 Results section Existence of transitions subsection.