| XRD in ambient air (20 °C, ~40 % relative humidity) | Both additives produced initially phase-pure 3C FAPbI₃; with β-alanine, the film transformed to the 2H FAPbI₃ phase in <1 hour; with L-arginine, the photoactive FAPbI₃ phase remained stable for >1000 hours |
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| XRD under 1 sun illumination in ambient air | FAPbI₃ thin films with L-arginine remained substantially stable |
| XRD patterns | Image data were not transcribed |
Benjamin M. Gallant, Satyawan Nagane, Thomas A. Selby, Visakh V. S. Pillai, Julia Wiktor, Ignacio Delso, Kieran W. P. Orr, Sangita Dutta, Shrestha Banerjee, Abhoy Karmakar, Affan N. Iqbal, Alessandro J. Mirabelli, Zher Ying Ooi, Clare P. Grey, Francesco Simone Ruggeri, Dominik J. Kubicki, Samuel D. Stranks. “Inducing surface symmetry breaking via organic molecule templating for phase-stable halide perovskites.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15007935/v1
The main paper refers to supporting information, but no separate supporting information file was available on the ChemRxiv article page
| ¹H and ¹³C NMR after mixing with FAI and PbI₂ | New ¹H signals appeared at ~8 ppm (9 and 10); the α-hydrogen resonances of L-arginine and β-alanine (3 and 4) were replaced by higher-frequency signals (8 and 11); E and Z isomers formed; the products were assigned as FA-arg⁺ and FA-ala⁺ |
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| ¹H and ¹³C NMR after mixing with FAI | Reaction with FA⁺ reached completion within minutes |
| ¹H and ¹³C NMR with PbI₂ | For L-arginine, complete reaction with FA⁺ required several days; at 75 °C, near-complete formation of FA-arg⁺ occurred within 30 minutes |
| Protonation-state assignment | FA-ala⁺ was present as a protonated carboxylic acid (COOH); FA-arg⁺ was present as a carboxylate (COO⁻) |
| ¹H NMR spectra | Image data were not transcribed |
| ¹H DOSY NMR, hydrodynamic radius | L-arginine: 12.8 Å; FA-arg⁺ after reaction with FA⁺: 14.7 Å |
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| ¹H DOSY NMR, hydrodynamic-radius change after PbI₂ addition | FA-arg⁺: ΔRh = 4.5 Å |
| ¹H DOSY NMR, hydrodynamic radius with excess FAI | FA-ala⁺: 7.4 Å |
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| ¹H DOSY NMR, hydrodynamic radius with excess FAI and PbI₂ | FA-ala⁺: 10.4 Å; ΔRh = 3.0 Å |
| ¹H DOSY NMR, hydrodynamic radius after PbI₂ addition | No increase |
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| ¹H MAS NMR (23.5 T, 55 kHz) | Strong broadening of FA-arg⁺ signals; individual environments could not be resolved; no signals were observed in the 9–14 ppm region |
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| ¹H-decoupled ¹H–¹³C CP MAS NMR (11.7 T, 12 kHz) | Strong broadening of FA-arg⁺ signals; individual environments could not be resolved; several overlapping signals were observed between 150–185 ppm |
| ¹H MAS NMR T₂ filtering | Confirmed T₂-driven broadening and increased rigidity of FA-arg⁺ when bound to the perovskite phase |
| MAS NMR assignment | FA-arg⁺ maintained its zwitterionic form from the precursor ink into the thin film; the ¹³C signals between 150–185 ppm were assigned to a range of COO⁻, amidinium and guanidinium environments |
| MAS NMR spectra | Image data were not transcribed |
| ¹H MAS NMR (23.5 T, 55 kHz) | Narrowing of the FA-ala⁺ signals; all FA-ala⁺ was assigned to a single, well-defined chemical environment |
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| ¹H-decoupled ¹H–¹³C CP MAS NMR (11.7 T, 12 kHz) | A single set of narrow FA-ala⁺ signals was detected |
| ¹H MAS NMR T₂ filtering | FA-ala⁺ had a substantially longer T₂ than FA-arg⁺ incorporated into FAPbI₃ thin films |
| ¹H–¹H spin-diffusion NMR | No cross peaks were observed between FA⁺ and FA-ala⁺ |
| ¹H MAS NMR | A high-frequency signal at 10.21 ppm (11) confirmed that carboxylic acid protonation in FA-ala⁺ was retained in the thin film |
| MAS NMR spectra | Image data were not transcribed |
| AFM-IR absorption | 1650 cm⁻¹, assigned to the COO⁻ asymmetric stretch of FA-arg⁺ |
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| AFM-IR normalization, nanolocalized averaged spectra | FA⁺ absorption at 1710 cm⁻¹ |
| AFM-IR normalization, averaged grain-boundary and grain-centre spectra | FA⁺ absorption at 1720 cm⁻¹ |
| AFM-IR spatial distribution | FA-arg⁺ was unevenly distributed across grain surfaces; concentrations were statistically higher near grain boundaries exhibiting well-defined crystal facets than at the centre of the same grain |
| AFM contact resonance | FA-arg⁺-rich grain-boundary regions exhibited increased perovskite-phase stiffness relative to grain centres and boundaries without increased FA-arg⁺ |
| AFM-IR and contact-resonance maps and spectra | Image data were not transcribed |
| AFM-IR C=O absorption, crystalline zwitterion | 1675 cm⁻¹ (νCOO⁻) |
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| AFM-IR C=O absorption, protonated COOH | 1739 cm⁻¹ (νCOOH) |
| AFM-IR spatial distribution | Uniform additive distribution |
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| AFM contact resonance at grain boundaries | No stiffening of the perovskite phase was observed |
| AFM-IR C=O absorption | FA-ala⁺: 1637 cm⁻¹; β-alanine: 1631 cm⁻¹ |
| AFM-IR maps and spectra | Image data were not transcribed |
| Scanning electron diffraction (~10 electrons Å⁻²; 5 nm probe; ~83 μm²; 2033 averaged patterns) | Superstructure reflections were observed only with FA-arg⁺; among patterns oriented near a <001>c zone axis, 11 % showed superstructure reflections; films with or without FA-ala⁺ contained a high density of {111}c twins/stacking faults and hexagonal polytype phases |
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| GIWAXS (10 keV) | A superstructure reflection at 26.0°, corresponding to the tetragonal-perovskite {121}t Bragg peak, was observed with FA-arg⁺ but not FA-ala⁺ |
| GIWAXS incidence-angle series | The superstructure reflection in FAPbI₃ with FA-arg⁺ had greater intensity at 0.1° incidence angle (~3 nm penetration depth) than at 0.6° (~170 nm penetration depth) |
| Electron-diffraction and GIWAXS patterns | Image data were not transcribed |