Two-Dimensional Lead(II) Halide-Based Hybrid Perovskites Templated by Acene Alkylamines: Crystal Structures, Optical Properties, and Piezoelectricity

Abstract

A series of two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals, based on acene alkylamine cations (i.e., phenylmethylammonium (PMA), 2-phenylethylammonium (PEA), 1-(2-naphthyl)methanammonium (NMA), and 2-(2-naphthyl)ethanammonium (NEA)) and lead(II) halide (i.e., PbX, X = Cl, Br, and I) frameworks, and their corresponding thin films were fabricated and examined for structure-property relationship. Several new or redetermined crystal structures are reported, including those for (NEA)PbI, (NEA)PbBr, (NMA)PbBr, (PMA)PbBr, and (PEA)PbI. Non-centrosymmetric structures from among these 2D HOIPs were confirmed by piezoresponse force microscopy-especially noteworthy is the structure of (PMA)PbBr, which was previously reported as centrosymmetric. Examination of the impact of organic cation and inorganic layer choice on the exciton absorption/emission properties, among the set of compounds considered, reveals that perovskite layer distortion (i.e., Pb-I-Pb bond angle between adjacent PbI octahedra) has a more global effect on the exciton properties than octahedral distortion (i.e., variation of I-Pb-I bond angles and discrepancy among Pb-I bond lengths within each PbI octahedron). In addition to the characteristic sharp exciton emission for each perovskite, (PMA)PbCl, (PEA)PbCl, (NMA)PbCl, and (PMA)PbBr exhibit separate, broad "white" emission in the long wavelength range. Piezoelectric compounds identified from these 2D HOIPs may be considered for future piezoresponse-type energy or electronic applications.

High‐Performance Perovskite Solar Cells with Enhanced Environmental Stability Based on a (p‐FC6H4C2H4NH3)2[PbI4] Capping Layer

“…The typical 2D perovskite packing of (FPEA) 2 PbI 4 is mimicking that of the well-known (PEA) 2 PbI 4 , with layers of corner-sharing octahedrons separated by head-to-head packed p-fluorophenyl ethyl amines (Figure 1b, Figure S1, Supporting Information). [42][43][44] Generally, they are analog materials except that (FPEA) 2 PbI 4 showed slightly larger lattice parameter and wider bandgap due to the presence of para-substituted fluoro Adv. [42][43][44] Generally, they are analog materials except that (FPEA) 2 PbI 4 showed slightly larger lattice parameter and wider bandgap due to the presence of para-substituted fluoro Adv.…”

Pressure‐Induced Broadband Emission of 2D Organic–Inorganic Hybrid Perovskite (C6H5C2H4NH3)2PbBr4

“…Therefore, we performed in situ high-pressure powder XRD experiments at room temperature to track the crystal structure evolution. [17] Figure 3b shows the layered crystal structure of (PEA) 2 PbBr 4 along the crystallographic c-axis. With the increase in pressure, all Bragg diffraction peaks shifted continuously along the large 2θ direction due to lattice contraction, and no new XRD peaks were observed.…”

Aromatic Alkylammonium Spacer Cations for Efficient Two‐Dimensional Perovskite Solar Cells with Enhanced Moisture and Thermal Stability

“…The devices fabricated using ACI perovskites yielded a PCE of 7.23%, but the device stability data are not available at present. There have been several attempts to synthesize 2D perovskites using different ammonium spacer cations such as histammonium, benzylammonium, hexylammonium ions, etc . Unfortunately, solar cells fabricated using these materials showed deficient photovoltaic performance.…”