Comparative Studies of Phonon Properties of Three-Dimensional Hybrid Organic–Inorganic Perovskites Comprising Methylhydrazinium, Methylammonium, and Formamidinium Cations

Abstract

Three-dimensional hybrid organic–inorganic perovskites with halide, formate, or hypophosphite ligands are promising photovoltaic, light-emitting, and multiferroic materials. Since the properties of these compounds are strongly affected by changes in lattice dynamics, it is of great importance to understand their phonon properties. We report Raman and IR spectra for a number of perovskites to understand the effect of various metal-linker frameworks on vibrations of methylhydrazinium, formamidinium, and methylammonium cations as well as effects of these cations on lattice phonons in lead bromide analogues. Our results show that the lattice dynamics and energy of lattice phonons of lead halides depend strongly on the type of organic cation and temperature. In particular, at room temperature, the dynamics of methylhydrazinium cations is much slower compared to the dynamics of methylammonium and formamidinium cations, implying weaker electron scattering in the former case and thus significantly different optoelectronic properties compared to the formamidinium and methylammonium analogues. We also show that the size of the halide ion affects the energy of internal modes, but this effect is much more pronounced when halide ligands are replaced by formate or hypophosphite anions, especially in the case of formamidinium analogues. We attribute this behavior to strong variation of hydrogen bond strength and changes in the internal structure of organic cations.

Effect of Dimensionality on Photoluminescence and Dielectric Properties of Imidazolium Lead Bromides

“…, Pb 2+ , Sn 2+ ), and X is a halide anion (Cl – , Br – , I – ). Three-dimensional (3D) lead halide perovskites were reported for only four organic cations: methylammonium (MA + ), 4 , 7 , 8 formamidinium (FA + ), 4 , 7 − 9 methylhydrazinium (MHy + ), 10 − 12 and aziridinium. 13 The most well-known MAPbI 3 and FAPbI 3 exhibit convenient solution processability as well as great optical and electrical properties for solar cell applications like narrow band gaps, high carrier mobility, and strong light absorption.…”

“…, Pb 2+ , Sn 2+ ), and X is a halide anion (Cl – , Br – , I – ). Three-dimensional (3D) lead halide perovskites were reported for only four organic cations: methylammonium (MA + ), ,, formamidinium (FA + ), ,− methylhydrazinium (MHy + ), − and aziridinium . The most well-known MAPbI 3 and FAPbI 3 exhibit convenient solution processability as well as great optical and electrical properties for solar cell applications like narrow band gaps, high carrier mobility, and strong light absorption. , On the other hand, recently discovered 3D MHyPbBr 3 exhibits four kinds of functional properties such as photoluminescence (PL), second-harmonic generation (SHG), two-photon excited PL, and switchable dielectric property, whereas MHyPbCl 3 shows PL and quadratic nonlinear optical (NLO) switching between two SHG-on states. , …”

Mixology of MA1-xEAxPbI3 Hybrid Perovskites: Phase Transitions, Cation Dynamics and Photoluminescence

“…and MAPbBr 3 leads to drastic narrowing of the Raman bands near 1590 and 920 cm −1 , 59,60 which is not observed for the x = 0.38 indicating lack of the MA ordering. We summarized the obtained results in the temperature-concentration phase diagram presented in Figure 2a.…”

“…and MAPbBr 3 59,60 indicating a substantial disorder related to the molecular cations even at low temperature. In particular, the tetragonal to orthorhombic phase transition in MAPbI 3…”

Hybrid Organic–Inorganic Crystals of [Methylhydrazinium]MIICl3 (MII = Co, Ni, Mn)

“…The factor group analysis is presented in Appendix 4 and Table S7. The proposed assignment, presented in Table S8, is based on comparative analysis with literature sources including MHyPbX 3 and MHy 2 PbX 4 (X = Cl, Br, I), [14][15][16]31,32 MHyMn(H 2 PO 2 ), 33,34 MHyM II (HCOO) 3 (M II = Mg, Fe, Mn, Zn), 35 as well as DFT calculations for the MHy + ion. 34 Bands corresponding to internal vibrations of MHy + are observed in characteristic ranges as reported in the literature.…”