| HAADF-STEM image analysis, 400 nanocubes | Mean projected edge length 36 ± 6 nm; average aspect ratio 1.07 |
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| Energy-dispersive X-ray spectroscopy (15 kV) | The material and the Pb and Br signals spatially coincided; Pb:Br ratio 1:3 at% |
| Laser diffraction, crystal size | 43 nm |
| Dynamic light scattering, hydrodynamic size | 48 nm |
| PVP shell thickness estimated from laser-diffraction and dynamic-light-scattering sizes | Roughly 2.5 nm |
| Powder X-ray diffraction, Scherrer fit to the (001) peak at 2θ = 14.93° | Corrected peak width β = 0.2023 ± 0.0046°; crystallite-size estimate 39 ± 2 nm |
| Powder X-ray diffraction, Rietveld refinement | Crystal system/space group: cubic/Pm-3m; lattice parameter a = 5.9337(1) Å; unit-cell volume V = 208.91(1) ų; preferred orientation: two-axis, r along [001] = 0.235 and r along [110] = 0.644; Rp = 4.9 %; Rwp = 6.3 %; Rexp = 5.4 %; χ² = 1.35; Bragg R-factor = 2.61 % |
| Powder X-ray diffraction, phase and orientation | Phase-pure cubic MAPbBr₃; preferred (001) orientation when dropcasted |
| Absorption, direct-band-gap Tauc fit | Eg = 2.34 eV = 530 nm; NEAR = 0.16 |
| Absorption, Urbach-tail fit | Urbach energy 23 meV |
| Photoluminescence quantum yield, excitation at 410 nm | 56 % |
| Photoluminescence, excitation wavelengths 300–505 nm in 2 nm intervals | PLE peak 3.06 eV; emission peak position 2.36 eV; FWHM 77 meV; the peak position and width were constant over the excitation range |
Susan A. Rigter, Christiaan T. van Campenhout, Sjoerd W. van Dongen, Peter Schall, Erik C. Garnett, Willem L. Noorduin. “Polyvinylpyrrolidone-capped MAPbBr₃ perovskite nanocrystals synthesized and processed in isopropanol.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15008017/v1
Numerical values and traces presented only in analytical plots and images in the main paper, pp. 5–9, and SI, pp. S2–S17, were not transcribed. The supporting information is appended to the main paper
| FTIR, MAPbBr₃–PVP nanocrystals | The characteristic perovskite and PVP bands were both present. The MA⁺ combination bands at 2392, 2501, 2724 and 2836 cm⁻¹ were strongly reduced. NH₃⁺ and CH₃ bends, the C–N stretch and the methyl-dominated rock were retained; N–H stretches, combination bands and the ammonium-dominated rock were lost or strongly changed |
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| FTIR, NH₃⁺ stretching-doublet Voigt fit, positions and FWHM (cm⁻¹) | Bulk MAPbBr₃: ν₁ 3127, 144; ν₇ 3222, 128. Nanocrystals: ν₁ 3135, 117; ν₇ 3207, 70. Relative component intensities were not quoted because the decomposition of the overlapping doublet was non-unique and the bulk ν₁ area was poorly constrained (±35 %) |
| FTIR, carbonyl position | Virtually unchanged between reference PVP and the nanocrystals; a bound minority, whether to MA⁺ or Pb²⁺, was not resolved |
| FTIR, ligand-interaction assignment | Assigned to hydrogen bonding between the pyrrolidone carbonyl of PVP and the methylammonium N–H; additional carbonyl–Pb²⁺ coordination could not be confirmed or ruled out |
| FTIR, unassigned bands | A band at ~1108 cm⁻¹ appeared for the nanocrystals, with a potentially corresponding band at ~1075 cm⁻¹ for MABr+PVP; the bands were absent from bulk MAPbBr₃, MABr and PVP alone |
| FTIR, residual isopropanol | IPA bands at 956, 1130 and 1160 cm⁻¹ were essentially absent from the washed nanocrystals. The O–H stretch of alcohol retained in the PVP film was ~3415 cm⁻¹, shifted from ~3366 cm⁻¹ for neat IPA, and was absent from the nanocrystals |
| Differential scanning calorimetry, room temperature to 150 °C | No features of nanocrystal degradation; a very small feature occurred around 80 °C. Bulk MAPbBr₃ showed an irreversible feature starting around 130 °C that was absent from the PVP-capped nanocrystals |
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| Differential scanning calorimetry, to 400 °C | Irreversible endothermic decomposition began around 130 °C for bulk MAPbBr₃ and began later for the nanocrystals. A decomposition reaction around 280 °C was present for both samples. A reaction around 380 °C was visible for the bulk sample and not for the nanocrystal sample; the nanocrystal sample showed a more gradual endothermic reaction towards 400 °C |
| STEM and energy-dispersive X-ray spectroscopy | Larger Ag nanocubes were assembled with smaller MAPbBr₃–PVP nanocrystals; the different materials were identified and differentiated, and strong colocalization of perovskite and silver nanoparticles was observed throughout the dropcasted sample |
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| Absorbance | The resonance peak of the Ag nanocubes overlapped with the absorption edge of the perovskite nanocrystals |