Synthesis, Crystal Structures, Optical Properties, and Phase Transitions of the Layered Guanidinium‐Based Hybrid Perovskites [C(NH₂)₃]₂MI₄; M = Sn, Pb

Abstract

The title compounds were obtained by the treatment of MI 2 in conc. HI with stoichiometric amounts of [C(NH 2 ) 3 ] 2 CO 3 . They show several phase transitions. The Pb/Sn HT phases {[C(NH 2 ) 3 ] 2 PbI 4 -I, Pnma, Z = 4, a = 13.04 Å, b = 13.62 Å, c = 9.36 Å} and {[C(NH 2 ) 3 ] 2 SnI 4 -I: a = 13.04 Å, b = 13.57 Å, c = 9.45 Å}, as well as [C(NH 2 ) 3 ] 2 PbI 4 -II (Pnnm, Z = 8, a = 27.03 Å, b = 9.31 Å, c = 12.92 Å) and [C(NH 2 ) 3 ] 2 SnI 4 -II (a = 26.89 Å, b = 9.30 Å, c = 12.94 Å) and also [C(NH 2 ) 3 ] 2 PbI 4 -III (P2 1 /n, Z = 8, a = 9.21 Å, b = 26.88 Å, c = 12.68 Å, = 90.49°) and [C(NH 2 ) 3 ] 2 SnI 4 -III (a = 9.28 Å, b = 26.95 Å, c = 12.81 Å, = 90.76°) are isotypic with each other. For [C(NH 2 ) 3 ] 2 SnI 4 the LT phase realizes a triclinic variant (P1, Z = 4, a = 9.27 Å, b = 12.67 Å, c = 14.44 Å, α = 66.98°, = 85.88°, γ = 88.26°). The [a] 1125 band gaps, the presented guanidinium-based hybrid perovskites are not suitable as dyes in (single junction) solid-state mesoscopic solar cells. Nevertheless, [C(NH 2 ) 3 ] 2 SnI 4 may be suitable as a top cell in tandem configurations.

New Type of 2D Perovskites with Alternating Cations in the Interlayer Space, (C(NH2)3)(CH3NH3)nPbnI3n+1: Structure, Properties, and Photovoltaic Performance

“…The present study expands on the series of simple 2D guanidinium compounds that adopt the <110>-oriented RP perovskite type, originally obtained by Szafrański and coworkers [37][38][39] and recently revisited by the Hillebrecht's group. 40 The ACI perovskites reported in this work find join the very recently reported GACs n Pb n X 3n+1 compounds which adopt a similar crystal structure. 41 Here the ACI phase GAMA n Pb n I 3n+1 series (n = 1, 2 and 3) has been structurally characterized by means of single-crystal X-ray diffraction.…”

Insight into the Mechanochemical Synthesis and Structural Evolution of Hybrid Organic–Inorganic Guanidinium Lead(II) Iodides

“…Daub et al. found two phase transitions for 2 from measurements at different temperatures . The changes are mostly based on a progressively more symmetric arrangement of the inorganic part.…”

“…The structure of 2 is described in detail in the literature . Compound 2 forms a layered ⟨110⟩‐oriented perovskite structure (Figure ).…”

“…The inorganic structures change with increasing number of included guanidinium iodide units from 1D double chains ( 1 ) to a 2D ⟨110⟩‐perovskite structure ( 2 ) to a 1D chain structure ( 3 ) and finally to isolated lead(II) iodide octahedra ( 4 ). The structure of compound 2 and its two high‐temperature analogues were recently described in detail by Szafrański et al and by Daub et al . The structures of 1 , 3 , and 4 were solved from single‐crystal and powder X‐ray diffraction (PXRD) data.…”

Tailoring the Band Gap in 3D Hybrid Perovskites by Substitution of the Organic Cations: (CH3NH3)1−2y(NH3(CH2)2NH3)2yPb1−yI3 (0≤y≤0.25)

“…The deficit of Pb 2+ was also confirmed by EDX measurements. With MAPbI 3 and Gu 2 PbI 4 (Gu=guanidinium) as references, we found an I:Pb ratio of around 3.8:1 for crystals of the synthesis with x =0.25. Experiments have shown that crystals containing H 2 en are not stable in an electron beam but decompose with the release of iodine.…”