Starting materials: FTO (10 Ω/sq, Nippon Sheet Glass), TiCl4, HBr, CH3NH2, PbBr2

Product: MAPbBr3 on TiO2-coated FTO, MAPbBr3 size 2-3mm. TiO2 film had a thickness of 8-12 μm. Powder is yellow

Description: Soak FTO in a 40 mM TiCl4 aqueous solution at 70 °C for 30 min to form a thin TiO2 buffer layer. Coat FTO with a commercial nanocrystalline TiO2 paste (refer to SI for more information) using a screen printer and sintering at 480 °C for 1 h in air. Synthesize CH3NH3Br by reacting HBr with 40% methylamine in methanol solution followed by recrystallization. Drop the TiO2 film into a 20 wt % stoichiometric solution of CH3NH3Br and PbBr2 in N,N-dimethylformamide. Subsequent film formation was done by spin-coating. The liquid precursor film coated on the TiO2 gradually changed color simultaneously with drying, indicating the formation of CH3NH3PbBr3 in the solid state.

Comment: The resultant mesoporous TiO2 (n-type semiconductor) film had a thickness of 8-12 μm. The liquid precursor film coated on the TiO2 gradually changed color simultaneously with drying, indicating the formation of CH3NH3PbI3 in the solid state. A vivid color change from colorless to yellow is observed.

Method: Powder X-ray diffraction

Description: X-ray diffraction analysis (Rigaku RINT- 2500). Refer to Page 6050: Paragraph 2.

• Rayan C Duke University

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: X-ray diffraction

Description: Bruker D8 Advance diffractometer (Bragg–Brentano geometry) equipped with a Cu-Ka X-ray tube operated at 40 kV and 40 mA. Refer to Page 9300 Section 3.1 Paragraph 2.

• Rayan C Duke University

Starting materials: HBr, CH3NH2, Pb(NO3)2

Product: MAPbBr3 Single-crystal

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 CH3NH3Br 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. Yield: 9.5 g.

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: X-ray diffraction

Description: CAD-4 four-circle diffractometer; Mo Kα, λ = 0.70926 Å (graphite monochromator); T = 18 °C. Lorentz, polarization, and absorption corrections applied. Refer to page 413 Experimental.

• Rayan C Duke University

Starting materials: N/A

Product: CH3ND3PbBr3 powder

Description: Samples were prepared following well-described methods [1,2]. In the case of the neutron sample, N-deuterated MAPB was produced by using fully deuterated DBr (MSD Isotopes), and reactor grade (499.8%) D2O (Atomic Energy of Canada Limited—AECL). The D2O was also used to deuterate all exchangeable hydrogens of the precursor chemicals prior to the final synthesis. A fine bright orange precipitate was formed which was filtered and transferred to a desiccating chamber prior to the diffraction measurements.

Comment: Synthesis references: [1] D. Weber, Z. Naturforsch. 33b (1978) 1443–1445. [2] O. Knop, R.E. Wasylishen, M.A. White, T.S. Cameron, M.J.M. Van Oort, Can. J. Chem. 68 (1990) 412–422.

Method: Powder neutron diffraction

Description: C2 diffractometer at Chalk River Laboratories, Chalk River, Ontario. The incident wavelength for Rietveld refinements: 1.32860(3)A˚. Data were collected and refined in two separate banks from 3–83° and 37–117° theta with wire-spacing 0.1° over the temperature range of 11–250K. Each bank was collected for 1 h. Refer to Page 104 Table 4.

Comment: Partially deuterated

• Rayan C Duke University

Starting materials: N/A

Product: CH3ND3PbBr3 powder

Description: Samples were prepared following well-described methods [1,2]. In the case of the neutron sample, N-deuterated MAPB was produced by using fully deuterated DBr (MSD Isotopes), and reactor grade (499.8%) D2O (Atomic Energy of Canada Limited—AECL). The D2O was also used to deuterate all exchangeable hydrogens of the precursor chemicals prior to the final synthesis. A fine bright orange precipitate was formed which was filtered and transferred to a desiccating chamber prior to the diffraction measurements.

Comment: Synthesis references: [1] D. Weber, Z. Naturforsch. 33b (1978) 1443–1445. [2] O. Knop, R.E. Wasylishen, M.A. White, T.S. Cameron, M.J.M. Van Oort, Can. J. Chem. 68 (1990) 412–422.

Method: Powder neutron diffraction

Description: C2 diffractometer at Chalk River Laboratories, Chalk River, Ontario. The incident wavelength for Rietveld refinements: 1.32860(3)A˚. Data were collected and refined in two separate banks from 3–83 ° and 37–117 ° 2theta with wire-spacing 0.1 ° over the temperature range of 11–250K. Each bank was collected for 1 h. Refer to Page 104 Table 4.

• Rayan C Duke University

Starting materials: N/A

Product: CH3ND3PbBr3 powder

Description: Samples were prepared following well-described methods [1,2]. In the case of the neutron sample, N-deuterated MAPB was produced by using fully deuterated DBr (MSD Isotopes), and reactor grade (499.8%) D2O (Atomic Energy of Canada Limited—AECL). The D2O was also used to deuterate all exchangeable hydrogens of the precursor chemicals prior to the final synthesis. A fine bright orange precipitate was formed which was filtered and transferred to a desiccating chamber prior to the diffraction measurements.

Comment: Synthesis references: [1] D. Weber, Z. Naturforsch. 33b (1978) 1443–1445. [2] O. Knop, R.E. Wasylishen, M.A. White, T.S. Cameron, M.J.M. Van Oort, Can. J. Chem. 68 (1990) 412–422.

Method: Powder neutron diffraction

Description: C2 diffractometer at Chalk River Laboratories, Chalk River, Ontario. Incident wavelength for Rietveld refinements: 1.32860(3)A˚. Data were collected and refined in two separate banks from 3–83 ° and 37–117 ° 2theta with wire-spacing 0.1 ° over the temperature range of 11–250K. Each bank was collected for 1 h. Refer to Page 104 Table 4.

• Rayan C Duke University

Starting materials: lead (II) acetate, CH3NH3+ (by adding a 40% solution of CH3NH2 in water), concentrated HBr

Product: Orange MAPbBr3 crystals

Description: CH3NH3PbBr3 was synthesized from lead (II) acetate and CH3NH3+ dissolved in concentrated HBr solution. The aqueous solution was cooled from l00°C to room temperature to obtain the orange crystals.

Method: temperature-dependent Guinier-Simon photograph

Description: No experimental details reported. Refer to Page 6374 Table I.

• Rayan C Duke University

Starting materials: lead (II) acetate, CH3NH3+ (by adding a 40% solution of CH3NH2 in water), concentrated HBr

Product: Orange MAPbBr3 crystals

Description: CH3NH3PbBr3 was synthesized from lead (II) acetate and CH3NH3+ dissolved in concentrated HBr solution. The aqueous solution was cooled from l00°C to room temperature to obtain the orange crystals.

Method: temperature-dependent Guinier-Simon photograph

Description: No experimental details reported. Refer to Page 6374 Table I.

• Rayan C Duke University

Starting materials: lead (II) acetate, CH3NH3+ (by adding a 40% solution of CH3NH2 in water), concentrated HBr

Product: Orange MAPbBr3 crystals

Description: CH3NH3PbBr3 was synthesized from lead (II) acetate and CH3NH3+ dissolved in concentrated HBr solution. The aqueous solution was cooled from l00°C to room temperature to obtain the orange crystals.

Method: temperature-dependent Guinier-Simon photograph

Description: No experimental details reported. Refer to Page 6374 Table I.

• Rayan C Duke University

Starting materials: lead (II) acetate, CH3NH3+ (by adding a 40% solution of CH3NH2 in water), concentrated HBr

Product: Orange MAPbBr3 crystals

Description: CH3NH3PbBr3 was synthesized from lead (II) acetate and CH3NH3+ dissolved in concentrated HBr solution. The aqueous solution was cooled from l00°C to room temperature to obtain the orange crystals.

Method: temperature-dependent Guinier-Simon photograph

Description: No experimental details reported. Refer to Page 6374 Table I.

• Rayan C Duke University

Starting materials: 40% aqueous CH3NH2 solution; concentrated HBr(aq); Pb(NO3)2 (aq; 0.021 molar)

Product: red-orange colored crystals

Description: Neutralize 20g of 40% aq. CH3NH2 solution with concentrated aq. HBr. At 100 deg. C, add aq. (0.021 mol) solution of Pb(NO3)2 by slow dripping while stirring vigorously. Crystals begin to form while stirring. Solution is filtrated after cooling to room temperature. The crystals are washed with n-butanol and subsequently benzene and are finally dried in vacuum. Nominal stoichiometry: C 2.51 wt.% H 1.26 wt.% N 2.92 wt.% Pb(II) 43.26 wt.% Br 50.05 wt.% Actual stoichiometry: C 2.49 wt.% H 1.3 wt.% N 2.97 wt.% Pb(II) 42.6 wt.% Br 49.6 wt.%

Method: Powder X-ray diffraction (PXRD)

Description: X-ray powder diagrams collected with a Debye-Scherrer camera using Cu K-alpha radiation (wave length 1.54178 Angstrom).

Comment: Miss Leonhardt recorded the PXRD diagrams.

• Kelly Ma

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.