Thermal and Structural Characterization of Methylammonium‐ and Formamidinium‐Halide Salts

Abstract

Four organic halide salts of interest to alloyed perovskite solar cell fabrication are characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), powder X‐ray diffraction (XRD), and thermogravimetric analysis. The chemical and crystal structures of methylammonium iodide (MAI), methylammonium bromide (MABr), and formamidinium iodide (FAI) are confirmed, and the experimental ATR‐FTIR spectrum and XRD pattern of formamidinium bromide (FABr) are presented. The enthalpy, ΔH vap, and entropy, ΔS vap, of vaporization are quantified for each salt and are used to estimate their vapor pressures in the temperature range of 150–300 °C. MAI, MABr, and FAI have similar vapor pressures in this temperature range, whereas FABr has a higher vapor pressure in the temperature range of 150–240 °C. These data provide a foundation for achieving effective control of vapor phase concentrations for vapor processing of alloyed perovskite solar cells.

Thermochemistry and crystal structure predictions of energetic derivatives of formamidine salts

“…Many of them are attractive building blocks in the search for the structure of new high-energy materials (HEMs), and low molecular weight formamidine (CH 4 N 2 ) (molecular weight 44) seems promising in this regard. It should also be noted that the halides of unsubstituted formamidines are important compounds in the field of solar energy, 10,11 while salts of azidosubstituted formamidines were considered as components of explosive compositions. 12–14…”

“…Many of them are attractive building blocks in the search for the structure of new high-energy materials (HEMs), and low molecular weight formamidine (CH 4 N 2 ) (molecular weight 44) seems promising in this regard. It should also be noted that the halides of unsubstituted formamidines are important compounds in the field of solar energy, 10,11 while salts of azidosubstituted formamidines were considered as components of explosive compositions. [12][13][14] In addition, we consider unsubstituted formamidine, and in its substituted version, compounds with the most famous explosophoric groups (nitro-and azido-), as well as an amino group, since it is known that the introduction of explosophoric groups into the structure of the compound makes it possible to increase their efficiency as a HEM.…”

Amine Salts Vapor Healing Perfected Perovskite Layers for NiOx Based p‐i‐n Solar Cells

“…[ 33 ] Hence, the vaporization process of A I X I powders was studied by thermogravimetric analysis (TGA) as shown and annotated detailedly in Figure S2 (Supporting Information). [ 35 ] In short, the low densities of MABr and FAI vapors diminished the reaction probability with the perovskite films under our mild reaction conditions. By contrast, the much higher volatility of MACl, FACl, and FABr resulted in higher vapor pressures, which could guarantee more effective vapor‐solid reactions and the subsequent permeation to the bottom NiO x layer.…”

Improving the Performance and High‐Field Stability of FAPbBr3 Single Crystals in X‐Ray Detection with Chenodeoxycholic Acid Additive

“…The DSC diagrams of C 0 ‐FAPbBr 3 SC and C 0.15 ‐FAPbBr 3 SC were shown in Figure a. The first dip of the heat‐flow diagram represents the decomposition of FABr in the FAPbBr 3 crystal [ 38 ] and the second dip is caused by the melting of PbBr 2 (CAS No. 10031‐22‐8).…”

“…The DSC diagrams of C 0 -FAPbBr 3 SC and C 0.15 -FAPbBr 3 SC were shown in Figure 3a. The first dip of the heat-flow diagram represents the decomposition of FABr in the FAPbBr 3 crystal [38] and the second dip is caused by the melting of PbBr C 0.15 -FAPbBr 3 SC in Figure 3b has an extra peak at 1794.95 cm −1 compared with that of the C 0 -FAPbBr 3 SC, which corresponds to the CO stretching vibration of CDCA. [39] The Pb 4f peaks in XPS spectrum of the C 0 -FAPbBr 3 SC in Figure 3c exhibit two characteristic peaks at 138.5 and 143.4 eV, corresponding to the spin-orbit splitting of the Pb 4f 7/2 and Pb 4f 5/2 constituents, respectively.…”