Bismuth/Silver-Based Two-Dimensional Iodide Double and One-Dimensional Bi Perovskites: Interplay between Structural and Electronic Dimensions

Abstract

New structures with favorable band structure and optical properties are of broad interest to the halide perovskite community. Recently, lead-free two-dimensional (2D) double perovskites have emerged as dimensionally reduced counterparts of their 3D analogues. Besides the structural diversity provided by the organic cation, the achievement of 2D lead-free iodide double perovskites has attached researchers to explore more structures in this new material family. Here, we report the synthesis and structures of a series of 2D iodide double perovskites based on cyclic diammonium cations (aminomethyl)piperidinium (AMP) and (aminomethyl)pyridinium (AMPY), (4AMP) 2 AgBiI 8 and (3AMPY) 2 AgBiI 8 , and compare them with 1D structures with Bi only (x-AMP)BiI 5 and (x-AMPY)BiI 5 (x = 3 and 4). The crystallographic structures of the double perovskite phases are highly distorted, because of the inability of Ag to form regular octahedral coordination with iodine. The experimental bandgaps of the double perovskite phases are surprisingly similar ((4AMP) 2 AgBiI 8 ) or even larger ((3AMPY) 2 AgBiI 8 ) than in the 1D structures with the same cations ((4AMP)BiI 5 and (3AMPY)BiI 5 ). DFT calculations suggest that the effective electronic dimensionality of the double perovskites is on par or lower than that of 1D structures. The reduced electronic dimension of the 2D compounds originates from the weak electronic coupling between the corner-sharing Ag and Bi octahedra. The band structures for the 1D compounds are dispersive in the chain direction, suggesting that their electronic and structural dimensions are similar. Low frequency Raman spectra exhibit distinct peaks at room temperature for all compounds reported here, suggesting rigid lattices.

m-Phenylenediammonium as a New Spacer for Dion–Jacobson Two-Dimensional Perovskites

“…Single crystals of (mPDA)­(MA) n −1 Pb n I 3 n +1 ( n = 1–3) were grown using a step-cooling method to avoid the precipitation of nonperovskite light-yellow phase, following the previous report. − In this method, the mixture is heated to boiling point to achieve complete dissolution. The temperature of the solution was then lowered to 120 °C, which is just below the boiling point of HI (127 °C), to exclusively obtain the 2D perovskite phases.…”

“…This can be seen in the mPDA compounds along Y–M x and Γ–X directions of the Brillouin zone for n = 2 and 3, respectively (Figure a,b). This is related to the short interlayer distance, especially when the closest I···I distance is similar to the van der Waals radii, which can lead to interlayer electronic coupling across the layers, with an antibonding character at the high-symmetry k -point. , This should be beneficial to the charge transport along the stacking direction, even though the charge mobility is still expected to be much larger in the in-plane direction (Table ). The valence band maximum (VBM) mainly consists of the hybridization between I 5p orbitals and Pb 6s orbitals, whereas the conduction band minimum (CBM) is dominated by the Pb 6p orbitals with a small contribution of I 5p orbitals (Figure S4), as expected from space group symmetries in 2D perovskites .…”

Silver‐Bismuth Based 2D Double Perovskites (4FPEA)4AgBiX8 (X = Cl, Br, I): Highly Oriented Thin Films with Large Domain Sizes and Ultrafast Charge‐Carrier Localization

“…The characteristic broad emission for these systems is also observed in other 2D silver-bismuth-halide, 2D lead-halide and 3D silver-bismuth-halide systems. [23,45,49,55,59] In Cs 2 AgBiBr 6 , it is generally attributed to substantial electronphonon coupling, leading to self-trapping or localization of the charge carriers or excitons. These self-trapped charge carriers subsequently diffuse to color centers and recombine, leading to the broad and strongly red-shifted PL.…”

“…Contrarily, while the DJ phases have an intrinsically stronger interlayer connectivity by binding one organic layer to two adjacent inorganic layers through the divalent character, RP phases also require a strong interaction between organic spacer molecules along the outof-plane direction. As of now, this synthetic difficulty has only yielded a small, but growing number of published structures, namely (CHD) 2 AgBiI 8 •H 2 O (CHD = 1,4-cyclohexandiamine), [43] (AE2T) 2 AgBiI 8 (AE2T = 5,5′-diylbis(aminoethyl)-[2,2′-bithiophene]), [34] (3AMPY) 2 AgBiI 8 (3AMPY = 3-(aminomethyl) pyridinium), [44] (4AMP) 2 AgBiI 8 (4AMP = (4-(aminomethyl) piperidinium), [45] (3IPA) 4 AgBiI 8 (IPA = 3-iodopropylammonium), [33] (4IBA) 4 AgBiI 8 (IBA = 4-iodobutylammonium), [46] (4AMP) 4 AgBiI 8 , [47] (APP) 4 AgBiI 8 (APP = 4-aminopiperidinium) and (β-MPA) 4 AgBiI 8 (β-MPA = β-methylphenethylammonium). [48] In our work, we used the simple modification of the PEA + cation to the 4FPEA + cation to achieve the stabilizing and templating effect.…”

Hybrid Layered Double Perovskite Halides of Transition Metals

“…Typical examples include (1,4-BDA)2AgBiBr8, 4 (AE2T)2AgBiI8, 5 (AMP)4[AgBiI8]2•H2O, 6 (CHDA)2CuBiI8•0.5H2O, 7 (CHDA)2AgBiI8.H2O, 7 (MPDA)2CuBiI8, 8 and (3AMPY)2AgBiI8•H2O (Table S1). [9][10][11] There has separately been considerable progress in the development of layered single perovskite halides of 2+ transition metals (TMs). [12][13][14][15][16] In addition, there is a report of mixed-valence Au + /Au 3+ based perovskite iodides containing [Au I Au III I6] 2layers of linear [Au I I2]and square planar [Au III I4]ions.…”