H/F Substitution on the Spacer Cations Leads to 1D-to-2D Increment of the Pyrrolidinium-Containing Lead Iodide Hybrid Perovskites

Abstract

Hybrid organic–inorganic perovskites (HOIPs) have emerged as multifunctional materials with remarkable optical and electronic properties. In particular, 2D-layered lead iodide-based HOIPs possess great practical application potential in the photoelectric field. In this work, we report H/F substitution-induced 1D-to-2D increment of lead iodide HOIPs. The enantiomeric HOIPs, S- and R-FPPbI3 (FP = 3-fluoropyrrolidinium), were achieved by monofluoride substitution on the spacer cations of the parent HOIP, PyPbI3 (Py = pyrrolidinium), showing mirror image structural relationship and reversible solid-state phase transition. A 2D-layered HOIP, (DFP)2PbI4 (DFP = 3,3-difluoropyrrolidinium), was achieved with a low band gap of 2.09 eV through difluoride substitution, thanks to the expansion of the Pb–I network from 1D to 2D. This work highlights the exploration of 1D chiral and 2D-layered HOIP materials with reversible phase transitions through H/F substitution strategies.

H/F Substitution Induced Enhancement of Phase Transition Temperature and Quantum Yield in Rare-Earth Hybrid Perovskite

“…The calculation result shows that, compared with the cations before F substitution, the void required by the cationic guest after F substitution is almost the same as the former (Table S6). This should be a credible reason for the increase of the movement energy barrier of organic cations and leads to increase of the T tr . − Of course, this is not enough to explain the increase of T tr . Thus, Hirshfeld surface analysis was performed to compare the intermolecular interactions between organic cations and the 2D inorganic framework of 1 and 2 . , A visualization map of the Hirshfeld surface of the molecular interactions of 1 and 2 at 230 K was obtained.…”

“…In recent decades, organic–inorganic hybrid perovskites (OIHPs) have attracted much attention due to their great potential applications in the fields of light, electricity, such as photoluminescence, dielectric switches, etc. − The OIHPs structure is composed of organic cations and inorganic anionic frameworks, combining the advantages of organic molecules and inorganic frameworks on the molecular level. − The unique structural composition makes OIHPs easy to derive and allows for structural diversity. − For OIHPs, minor changes in the guest cationic modification synergistic host framework usually achieve changes in molecular packing, thereby realizing macroscopic performance regulation. − For example, halogen substitution enhances intermolecular interactions (e.g., hydrogen bonding or metal–halogen coordination) between cations and anions to increase the guest kinetic energy barrier to increase the phase transition temperature ( T tr ). − For another, the halogen substitution of the guest cations also can cause twists of the host framework. − Therefore, changes occur in the coordination environment between the B-site metal ions and halide of the inorganic framework in OIHPs.…”

Excellent Switchable Properties, Broad-Band Emission, Ferroelectricity, and High Tc in a Two-Dimensional Hybrid Perovskite: (4,4-DCA)2PbBr4 Exploited by H/F Substitution

“…This strong polarity introduced by fluorine substitution also leads to stronger van der Waals interactions between adjacent layers of organic cations, significantly increasing the phase transition temperature of 2D organic−inorganic hybrid perovskite materials. 15 24 In addition, the organic components, including interlayer cations and framework cations, can influence the distortion (deviation from perfect octahedra) of each octahedron, thereby adjusting its electronic properties. 25 Inspired by these results, rational H/F substitution design and assembly hold the potential to unlock 2D hybrid perovskites as promising candidates for highperformance, multifunctional materials with switchable properties.…”

Homochiral Chemistry Strategy to Trigger Second-Harmonic Generation and Dual Dielectric Switches

“…In past studies, a rational design of organic molecules has been commonly used to achieve structural phase transitions and to realize switchable materials, such as halogen substitution, molecular doping, and solvent modulation. − However, these cannot be precisely designed for multichannel functionally switchable materials. Here, we introduce a single chiral strategy, − where the introduction of chiral molecules allows the compound to crystallize in chiral space groups: 1 ( C 1 ), 2 ( C 2 ), 222 ( D 2 ), 4 ( C 4 ), 422 ( D 4 ), 3 ( C 3 ), 32 ( D 3 ), 6 ( C 6 ), 622 ( D 6 ), 23 ( T ), and 432 ( O ).…”