Supporting Information Molecular Origin of Properties of Organic ...

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Supporting Information Molecular Origin of Properties of Organic-Inorganic Hybrid Perovskites: the Big Picture from Small Clusters Hong Fang, Puru Jena Department of Physics, Virginia Commonwealth University, 701 West Grace Street, 23284, VA, United States

Table S1 Calculated ionization potential and electron affinity for organic cations and inorganic anions in the hybrid perovskites. .................................................................................................................................. 2 Figure S1: Optimized structures of the molecular clusters with minimum energy and no imaginary vibrational frequency. ................................................................................................................................... 3 Figure S2: Calculated UV-vis spectra for the studied molecular admixtures. ............................................ 14 FigureS3: Calculated HOMO-LUMO gaps and the exciton binding energyies for the studied molecules. .................................................................................................................................................................. .28 Table S2 Data of calculated HOMO-LUMO gaps and optical gaps. .......................................................... 35 Figure S4: Schematic plots showing the three ways to change the atomic distance. .................................. 35 Figure S5: Calculated gap deformation potentials. . ................................................................................... 36 Figure S6: DFT-PBE calculated electronic density of states (DoS) for the crystalline admixtures MASnI2(BH4) and MAGeI2(BH4). .............................................................................................................. 36 Table S3 Experimental data of band gaps and exciton binding energy of direct bandgap semiconductors. .................................................................................................................................................................... 38 Figure S7: Collected data of direct bandgap semiconductors and the studied molecules. .......................... 39

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Table S1 Calculated ionization potential and electron affinity for organic cations and inorganic anions in the hybrid perovskites. Ionization potential (eV) Electron affinity (eV) Lithium ion 5.62 3.71 Cl− Li+ Ammonium 4.35 4.14 [GeCl3]− [NH4]+ Hydroxylammonium 4.08 4.90 [GeBr3]− [NH3OH]+ Mehylammonium 4.13 3.99 [GeI3]− [CH3NH3]+ Hydrazinium 4.09 4.40 [SnCl3]− [NH3NH2]+ Azetidinium 3.71 4.25 [SnBr3]− [(CH2)3NH2]+ Formamidinium 4.12 4.81 [SnI3]− [CH(NH2)2]+ Imidazolium 4.76 3.14 [PbBr3]− [C3N2H5]+ Dimethylammonium 3.75 4.42 [PbI3]− [(CH3)2NH2]+ Ethylammonium 3.42 3.89 [BH4]− [CH3CH2NH3]+ Guanidinium 4.46 4.25 [Ge(BH4)3]− [(NH2)3C]+ Tetramethylammoium 2.81 4.41 [Sn(BH4)3]− [(CH3)4N]+ Thiazolium 3.71 5.19 [Ge(HCOO)3]− [C3H4NS]+

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Figure S1: Optimized structures of the molecular clusters with minimum energy and no imaginary vibrational frequency.

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Figure S2: Calculated UV-vis spectra for the studied molecular admixtures. The envelopes are the onsets of the spectra with a broadening of 0.33 eV. The peaks are plotted using a 0.01 eV broadening of the spectra. The first peak in each case corresponds to the value of the optical gap. Both representations show the blue shift according to x = 0-3, corresponding to red, light red, cyan and blue, respectively.

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FigureS3: Calculated HOMO-LUMO gaps using DFT-B3LYP (in blue circle) and CCSD(T) (in purple square) compared to the experimental band gaps (in red triangle) for the studied hybrid perovskites. The calculated exciton binding energies of the molecules are shown as the open stars. In each case, the solid line in the right panel shows the least-square fitting to the CCSD(T) relative gaps.

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Table S2 CCSD(T) and TDDFT+B3LYP calculated HOMO-LUMO gaps (eV) and optical gaps (eV), respectively, of the studied molecules. The exciton binding energy (eV) is calculated as the difference between the two gaps. MA and FA denote CH3NH3 and HC(NH2)2, respectively. Molecules HOMO-LUMO gap Optical gap Exciton binding energy CsSnI3 7.926 3.915 4.011 CsSnBr3 8.407 4.428 3.979 MAPbI3 9.228 3.893 5.335 MAPbBr3 10.128 4.518 5.610 MAPbCl3 10.803 5.216 5.587 FAPbI3 9.141 3.507 5.634 FAPbBr3 9.959 4.118 5.841 MASnI3 9.186 3.820 5.366 MASnBr3 9.858 4.782 5.076 MASnCl3 10.506 5.376 5.130 MAGeI3 9.336 3.792 5.544 MAGeBr3 10.074 4.704 5.370 MAGeCl3 10.490 5.332 5.158 FAGeI3 9.220 3.306 5.914 FAGeBr3 9.834 3.664 6.170 MAPb(BH4)3 11.148 5.283 5.865 FAPb(BH4)3 11.073 4.736 6.337 MASn(BH4)3 10.624 5.275 5.349 MAGe(BH4)3 10.950 5.411 5.539 FAGe(BH4)3 10.774 4.329 6.445 MAGe(HCOO)3 11.563 5.356 6.207 FAGe(HCOO)3 11.535 5.188 6.347 Figure S4: Schematic plots showing the three ways to change the atomic distance: (a) reducing the distance by evenly drawing the two atoms closer relative to the mid-point of the connecting line (Em in paper); (b) reducing the distance by only moving the cation along the line connecting Cs and Sn (Ec in paper); and (c) reducing the distance by only moving Sn along the line connecting Cs and Sn (Es in paper). In each case the position of halogens (in red) are kept fixed.

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Figure S5: Calculated change of gap Ec (in red circle), Em (in black square) and Es (in blue triangle) with the change of Cs-Sn interatomic distance for (a) CsSnBr3 and (b) CsSnI3 molecules.

Figure S6: DFT-PBE calculated electronic density of states (DoS) for the crystalline admixtures MASnI2(BH4) and MAGeI2(BH4). In each case, partial DoS analysis has been carried out. The top of the valance band is at zero energy. “H_dos” denotes the total DoS of hydrogen. “Hc_dos” denotes the total DoS of hydrogen associated with the cation. “Ha_dos” denotes the DoS from hydrogen associated with the anion. The figure shows that, in these admixtures, the top of the valence band (hence the band gap) is determined by iodine other than BH4. This should also apply to other admixtures with the halogen partially replaced by [BH4]−, given the similarity of the electronic structures of the studied hybrid perovskites.

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Table S3 Experimental data of band gaps and exciton binding energy of direct bandgap semiconductors. These data are used in Figure S7. Semiconductor Band gap (eV) Exciton binding energy (meV) InSb 0.23 0.46 GaSb 0.77 1.47 GaAs 1.43 4.42 CdSe 1.73 13.68 ZnTe 2.33 11.76 CdS 2.48 26.29 CuCl 3.07 134.33 TlCl 3.44 12.37 CuBr 3.08 108.00 Cu2O 2.17 150.00 ZnS 3.78 36.00 GaN 3.49 28.00 ZnO 3.44 61.00 ZnSe 2.80 19.00 CdTe 1.60 10.5 InP 1.42 5.10

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Figure S7: Collected data (open circles) of direct bandgap semiconductors (Table S3) and the studied molecules. The y-axis is in the power of ten. The solid line shows the least square fitting using Eq. (8) in the paper.

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