Adjacent Cations Research Articles

Hydrogen Diffusion in Hybrid Perovskites from Exchange NMR.

Ion migration is an important phenomenon affecting the performance of hybrid perovskite solar cells. It is particularly challenging, however, to disentangle the contribution of H+ diffusion from that of other ions, and the atomic-scale mechanism remains unclear. Here, we use 2H exchange NMR to prove that 2H+ ions exchange between MA+ cations on the time scale of seconds for both MAPbI3 and FA0.7MA0.3PbI3 perovskites. We do this by exploiting 15N-enriched MA+ to label the cations by their 15N spin state. The exchange rates and activation energy are then calculated by performing experiments as functions of mixing time and temperature. By comparing the measured exchange rates to previously measured bulk H+ diffusivities, we demonstrate that, after dissociating, H+ ions travel through the lattice before associating to another cation rather than hopping between adjacent cations.

Radical cations of chalcogenanthrenes with halogenido metalate anions. Part I: tetramethoxythianthrene

Abstract The electron-rich molecule tetramethoxythianthrene TMO-TA can readily be oxidized to the radical cation using various transition metal halides in acetonitrile as solvent. Reactions with CuBr2, FeCl3, AuCl3, NbCl5, and CuCl2 yield dark blue or black crystals of [TMO-TA]2[CuBr4] (2), [TMO-TA][FeCl4] · CH3CN (3), [TMO-TA][AuCl4] (4), [TMO-TA][NbCl6] · CH3CN (6), and [TMO-TA]5[Cu2Cl6]2 · 2 CH3CN (7). [TMO-TA]2[Ta2OF10] (5) was obtained by anodic oxidation of TMO-TA in the presence of (Nbu4)2[Ta2OF10] as electrolyte. Using mercury(II) bromide, no redox reaction occurs. Instead, the colorless complex [HgBr2(TMO-TA)] (1) is formed. In the crystal structures of the compounds 2–7, the almost planar radical cations show different types of arrangements. Pair formation of the [TMO-TA]•+ radicals to [TMO-TA]2 2+ dimers with the typical intra-pair S⋯S bonds of 3.1–3.2 Å lengths is predominant. Compounds 6 and 7 contain stacks of planar TMO-TA molecules in equidistant arrangement without pair formation and the unique feature of rotation of each adjacent cation by about 30°. Compounds 2, 5, and 7 are electrical semiconductors with band gaps between 0.62 and 1.4 eV, reflecting the arrangement of the radical cations. While 5 is diamagnetic, the magnetic momenta of 2 and 7 correspond only to the expected paramagnetic momenta of magnetically dilute Cu2+ ions. Electrons on the organic radicals are strongly paired in all compounds.

Discovery of atomic clock-like spin defects in simple oxides from first principles

Virtually noiseless due to the scarcity of spinful nuclei in the lattice, simple oxides hold promise as hosts of solid-state spin qubits. However, no suitable spin defect has yet been found in these systems. Using high-throughput first-principles calculations, we predict spin defects in calcium oxide with electronic properties remarkably similar to those of the NV center in diamond. These defects are charged complexes where a dopant atom — Sb, Bi, or I — occupies the volume vacated by adjacent cation and anion vacancies. The predicted zero phonon line shows that the Bi complex emits in the telecommunication range, and the computed many-body energy levels suggest a viable optical cycle required for qubit initialization. Notably, the high-spin nucleus of each dopant strongly couples to the electron spin, leading to many controllable quantum levels and the emergence of atomic clock-like transitions that are well protected from environmental noise. Specifically, the Hanh-echo coherence time increases beyond seconds at the clock-like transition in the defect with 209Bi. Our results pave the way to designing quantum states with long coherence times in simple oxides, making them attractive platforms for quantum technologies.

The role of vanadium substitution in the oxygen sublattice disorder of Ba7Nb4MoO20-based hexagonal perovskite oxide-ion conductors.

Ba7Nb4MoO20-based hexagonal perovskite derivatives are promising oxygen-ion conductors for solid electrolytes in solid-oxide fuel cells and electrolysers. A thorough understanding of chemical substitution and its impact on structural features conducive to high ionic conductivity is fundamental for decreasing the operation temperature of such devices. Here, a new 7H polytype-based composition, namely Ba7Nb3.9-x V x Mo1.1O20.05, is investigated to assess the effect of vanadium substitution. Structural changes upon V incorporation are studied using X-ray and neutron diffraction, as well as 51V and 93Nb solid-state nuclear magnetic resonance spectroscopy. For the undoped composition at room temperature, two distinct oxygen sites (O1 and O5) are found along the palmierite-like layer, corresponding to a mix of four- and six-fold coordination for adjacent M2 cations. At high temperature (527 °C), reorganization of oxygen results in the major occupation of O1 and four-fold (tetrahedral) coordination of the M2 cations. The same rearrangement is observed upon V-substitution, but already at room temperature. From 51V NMR, we identified a tetrahedral coordination for V5+ cations, indicating their preferential occupation of the M2 site. This preferential occupation by V5+ cations is correlated with increasing tetrahedral coordination of Nb5+ cations as observed from 93Nb NMR. Altogether, these observations indicate that V-substitution impacts the oxygen sublattice so as to mimic the high-temperature structure. Additionally, BVSE calculations demonstrate a decreasing energy barrier for O2- migration associated with the presence of vanadium in the structure. This conclusion corroborates the hypothesis that vanadium's propensity for a lower coordination number is beneficial for promoting high O2- mobility in this promising class of oxide-ion conductors.

A zinc coordination compound showing green photoluminescence

Abstract A novel three-dimensional coordination compound has been solvothermally synthesized based on a tetracarboxylate ligand H4L (H4L = 1,3,6,8-tetrakis(4-carboxylphenyl)pyrene), Zn2L(H2O)2·2DEF (1) (DEF = N,N′-diethylformamide). Each Zn ion is coordinated by four carboxylate oxygen atoms from four L4− ligands and one oxygen atom from a water molecule to provide a distorted square-pyramidal geometry. Pairs of adjacent Zn cations are bridged by four carboxylate groups of four different L4− ligands to generate a paddle-wheel [Zn2(COO)4(H2O)2] secondary building unit (SBU). Each SUB is further linked to four L4− ligands to give a three-dimensional framework with cds-type (CdSO4-type) topology. The crystal structure has been determined via single-crystal X-ray diffraction, and the compound was characterized by elemental and thermal analysis, infrared spectroscopy, powder X-ray diffraction, and solid-state photoluminescence measurements.

Autonomous enrichment and deep removal of heavy metals by salt-tolerant gradient polyelectrolyte hydrogels

The integration of nanostructured materials into hydrogel matrix with chemical gradient holds great promise in gathering the pollutants and enhancing their adsorption or photocatalytic performance. However, the electric potentials rooting in the common gradient polyelectrolyte hydrogel are almost completely shielded by the co-existing counter-ions. In this study, a salt-tolerant gradient polycationic electrolyte hydrogel was fabricated by free radical copolymerization under the induction of unilateral UV illumination, which was used as nanofillers matrix. The cation-π interactions between the adjacent cations and aromatic rings endow the gradient polycationic electrolyte hydrogels deserving the salt-tolerant properties. Thus, the build-in electric potentials are still reactive on enrichment of the anionic heavy metals in highly concentrated salt solutions, altering the defects of the common gradient polyelectrolyte hydrogel. Using Sb(V) adsorption and Cr(VI) photocatalytic reduction as target reactions, the gradient composite hydrogels always display fast and high removal capacities towards these anionic pollutants in the saline solutions of 500 mM, as well as good stability and reusability. This salt-tolerant hydrogel matrix provides a smart material platform with self-driven forces in the fields of pollutant enrichment and removal.

Metal halide coordination compounds with quinazolin-4(3H)-one.

Three coordination compounds of quinazolin-4(3H)-one (quinoz; C8H6N2O) with divalent group 12 halides are reported. In all complexes, coordination occurs via the nitro-gen atom ortho to the quinazolinone carbonyl group. In the two chain polymers with composition [MX 2(quinoz)], viz. (M = Cd, X = Br), catena-poly[[[quinazolin-4(3H)-one-κN 3]cadmium(II)]-di-μ-bromido], [CdBr2(C8H6N2O)]n (I), and M = Hg, X = Cl, catena-poly[[[quinazolin-4(3H)-one-κN 3]mercury(II)]-di-μ-chlorido], [HgCl2(C8H6N2O)]n (II), the divalent cations are five-coordinate, with four bridging halide and one terminal quinoz ligand. The CdII atom in (I) has an almost trigonal-bipyramidal coordination environment, whereas the HgII atom in (II) has a more distorted coordination environment. Likewise, the halide bridges in (II) are significantly more asymmetric than in (I). In both (I) and (II), quinoz ligands at adjacent cations along each strand are oriented in opposite directions, and the organic ligands of neighboring strands inter-digitate with resulting π-π inter-actions. In contrast to the halide-bridged chain polymers (I) and (II), the adduct of quinoz with CdI2 is the tetra-hedral complex [CdI2(quinoz)2], di-iodido-bis-[quinazolin-4(3H)-one-κN 3]cadmium(II), [CdI2(C16H12N4O2)], (III). The CdII atom in this discrete complex is located on a twofold rotation axis. Disorder in (III) is reflected in an alternative minority orientation of the mol-ecules for which the iodine sites closely match the position of the majority orientation. In view of the low site occupancy of only 0.0318 (8) Å, only the CdII position for this alternative orientation was taken into account during refinement. In all three compounds, classical N-H⋯O hydrogen bonds with donor-acceptor distances of ca 2.9 Å occur; they link the polymer chains in (I) and (II) into di-periodic networks and connect adjacent discrete complexes in (III) to mono-periodic strands.

Improving the Properties of Anion Exchange Blend Membranes via Optimizing the NPBI Content and Deprotonation Degree: A Theoretical Study

Blending poly[2,2′-(1,4-naphthalene)-5,5′-benzimidazole] (NPBI) with main chain-type N-spirocyclic quaternary ammonium ionenes (SI) could effectively improve the dimensional stability of anion exchange blend membranes (AEBMs), while the mechanism of the effect on OH– transport has not been elucidated. In this work, the effect of the NPBI content and deprotonation degree on OH– transport was revealed by molecular dynamics simulation. The simulation results showed that the free water content increased with increasing NPBI content at the same NPBI deprotonation degree, which facilitated the OH– transport. However, the decreased distance between adjacent N-spirocyclic quaternary ammonium cations (NSQAs) in the interchain and the increased correlation between OH– were detrimental to OH– transport. These resulted in AEBMs with 20 wt % NPBI content exhibiting the best OH– transport. When the NPBI content was 20 wt %, the distance between adjacent NSQAs in the interchain increased and OH– was more dispersed in the aqueous phase with decreasing NPBI deprotonation degrees, leading to the increased OH– transport. Because of the “trade-off” effect between the OH– transport and dimensional stability of AEBMs, we suggest that AEBMs with 20 wt % NPBI content and 50% NPBI deprotonation degree (SI/NP-50-20) can be selected to balance OH– transport and dimensional stability. This work will provide further guidance for the design of blend modification of AEBMs.

Syntheses, crystal structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine.

The structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine are discussed. In 4-(4-nitro-phen-yl)piperazin-1-ium salicylate (C10H14N3O2 +·C7H5O3 -), there are strong hydrogen bonds between cation and anion and the 4-nitro-phenyl substituent occupies an equatorial position in the piperazinium ring. The cation and anion are linked together by supra-molecular inter-actions [graph-set notation of hydrogen bonding (6) propagating in the a-axis direction]. Additionally, there is π-π stacking involving the salicylate anion and the piperazinium cation in adjacent asymmetric units as well as a C-H⋯π inter-action between a hydrogen atom on the piperazine ring and the phenyl ring within the salicyclate anion. In bis-[4-(4-nitro-phen-yl)piperazin-1-ium] bis-(4-fluoro-benzoate) trihydrate (2C10H14N3O2 +·2C7H4FO2 -·3H2O), there are two cations, two anions, and three water mol-ecules of solvation in the asymmetric unit, all linked by hydrogen bonds [graph-set notation of hydrogen bonding R 2 2(20) between adjacent cations and R 3 3(9) between a cation and its adjacent anion]. In the anion, the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, which is relatively rare. Within the asymmetric unit, the phenyl groups in the cations show an offset π-π inter-action. Additionally, there is a C-H⋯π inter-action between a hydrogen atom on the phenyl ring within a cation and the phenyl ring within an anion. In 4-(4-nitro-phen-yl)piperazin-1-ium 3,5-di-nitro-benzoate (C10H14N3O2 +·C7H4N2O6 -), there is a strong N-H⋯O hydrogen bond linking the cation and anion and the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, as seen in the previous structure. In the crystal, the cation and the anion form a complex three-dimensional hydrogen-bonded array involving R 2 2(8), R 4 4(12) and R 4 4(20) rings propogating in the a-axis direction. The nitro-phenyl group is disordered with occupancies of 0.806 (10) and 0.194 (10).

Charge-Segregated Stacking Structure with Anisotropic Electric Conductivity in NIR-Absorbing and Emitting Positively Chargedπ-Electronic Systems.

Squarylium-based π-electronic cation with an augmented dipole was synthesized by methylation of zwitterionic squarylium. The cation formed various ion pairs in combination with anions, and the ion pairs exhibited distinct photophysical properties in the dispersed state, ascribed to the formation of J- and H-aggregates. The ion pairs provided solid-state assemblies based on cation stacking. It is noteworthy that complete segregation of cations and anions was observed in a pseudo-polymorph of the ion pair with pentacyanocyclopentadienide as a π-electronic anion. In the crystalline state, the ion pairs exhibited photophysical properties and electric conductivity derived from cation stacking. In particular, the charge-segregated ion-pairing assembly induces an electric conductive pathway along the stacking axis. The charge-segregated mode and fascinating properties were derived from the reduced electrostatic repulsion between adjacent π-electronic cations via dipole-dipole interactions.

An anomalous ferroelastic phase transition arising from an unusual cis-/anti-conformational reversal of polar organic cations.

Hybrid ferroelastics have attracted increasing attention for their potential application as mechanical switches. The sporadically documented anomalous ferroelastic phase transitions, i.e., ferroelasticity that appears at a high-temperature phase rather than a low-temperature phase, are of particular interest but are not well understood at the molecular level. By judiciously choosing a polar and flexible organic cation (Me2NH(CH2)2Br+) with cis-/anti- conformations as an A-site component, we obtained two new polar hybrid ferroelastics, A2[MBr6] (M = Te for 1 and Sn for 2). These materials undergo distinct thermal-induced ferroelastic phase transitions. The larger [TeBr6]2- anions anchor the adjacent organic cations well and essentially endow 1 with a conventional ferroelastic transition (P21 → Pm21n) arising from a common order-disorder transition of organic cations without conformational changes. Moreover, the smaller [SnBr6]2- anions can interact with the adjacent organic cations in energetically similar sets of intermolecular interactions, enabling 2 to undergo an anomalous ferroelastic phase transition (P212121 → P21) arising from an unusual cis-/anti-conformational reversal of organic cations. These two instances demonstrate the importance of the delicate balance of intermolecular interactions for inducing anomalous ferroelastic phase transitions. The findings here provide important insights for seeking new multifunctional ferroelastic materials.

Placing gold on a π+-surface: ligand design and impact on reactivity.

We describe a novel gold chloride complex supported by an ambiphilic phosphine/xanthylium ligand in which the AuCl moiety interacts with the π+ surface of the xanthylium unit as indicated by structural studies. Energy decomposition analyses carried out on a model system indicates the prevalence of non-covalent interactions in which the electrostatic and dispersion terms cumulatively dominate. The presence of these AuCl-π+ interactions correlates with the high catalytic activity of this complex in the cyclisation of 2-(phenylethynyl)phenylboronic acid, N-propargyl-t-butylamide, and 2-allyl-2-(2-propynyl)malonate. Comparison with the significantly less active acridinium and the 9-oxa-10-boraanthracene analogues reinforces this conclusion.

Rational Positioning of Metal Ions to Stabilize Open Tin Sites in Beta Zeolite for Catalytic Conversion of Sugars

AbstractVia hydrothermal synthesis of Sn‐Al gels, mild dealumination and ion exchange, a bimetallic Sn‐Ni‐Beta catalyst was prepared which can convert glucose to methyl lactate (MLA) and methyl vinyl glycolate (MVG) in methanol at yields of 71.2 % and 10.2 %, respectively. Results from solid‐state magic‐angle spinning nuclear magnetic resonance, X‐ray photoelectron spectroscopy, transmission electron microscopy, spectroscopic analysis, probe‐temperature‐programmed desorption, and density functional theory calculations conclusively reveal that the openness of the Sn sites, such as by the formation of [(SiO)3−Sn−OH] entities, is governed by an adjacent metal cation such as Ni2+, Co2+, and Mn2+. This relies on the low structure‐defective pore channel, provided by the current synthesis scheme, and the specific silica hydroxyl anchor point is associated with the incorporation of Sn for additional and precise metal ion localization. The presence of metal cations significantly improved the catalytic performance of Sn‐Ni‐Beta for glucose isomerization and conversion to MLA of sugar compared with Sn‐Beta.

Rational Positioning of Metal Ions to Stabilize Open Tin Sites in Beta Zeolite for Catalytic Conversion of Sugars.

Via hydrothermal synthesis of Sn-Al gels, mild dealumination and ion exchange, a bimetallic Sn-Ni-Beta catalyst was prepared which can convert glucose to methyl lactate (MLA) and methyl vinyl glycolate (MVG) in methanol at yields of 71.2% and 10.2%, respectively. Results from solid-state MAS NMR, XPS, TEM, spectroscopic analysis, probe-TPD, and DFT calculations conclusively reveal that the openness of the Sn sites, such as by the formation of [(SiO)3-Sn-OH] entities, is governed by an adjacent metal cation such as Ni2+, Co2+, and Mn2+. This relies on the low structure-defective pore channel, provided by the current synthesis scheme, and the specific silica hydroxyl anchor point is associated with the incorporation of Sn for additional and precise metal ion localization. The presence of metal cations significantly improved the catalytic performance of Sn-Ni-Beta for glucose isomerization and conversion to MLA of sugar compared with Sn-Beta.

Synergy of Host–Guest and Cation−π Interactions for an Ultrastretchable, pH-Tunable, Surface-Adaptive, and Salt-Resistant Hydrogel Adhesive

The adhesion to wet, acidic, and saline biointerfaces with large deformation is important in the fields of wound dressing and motion monitoring but has proven to be extremely challenging. There is a need for a facile method to improve the stretchability and salt resistance simultaneously. Here, an ultrastretchable, pH-tunable, surface-adaptive, and salt-resistant hydrogel adhesive is reported. The hydrogel adhesive is prepared through cross-linking acrylamide with a supramolecular complex of poly(β-cyclodextrin) (PCD) and benzimidazole (BI). The dynamic association between PCD and BI causes an extra energy dissipation and improves the breaking strain to be larger than 4000%. The hydrogel exhibits stable adhesiveness to varieties of surfaces due to the multiple types of hydrogel–surface interactions, including ionic bond, π–π stacking, and hydrogen bond. Notably, the adhesive strength of the hydrogel gets significantly enhanced in an acidic environment and shows no attenuation in a saline environment. This is due to the unique adjacent cation−π structure of BI: the imidazole can be protonized upon acidification, and the phenyl group can repel water and enhance the ionic attraction with the substrates. The ultrastretchability, the stable adhesion on biointerfaces, and the salt resistance render the hydrogel a promising candidate for the surgical patch and motion sensors that serve in wet, acidic, and dynamic environments.

Mass-Resolved Momentum Imaging of Three Dichloroethylene Isomers by Femtosecond Laser-Induced Coulomb Explosion

Coulomb explosion experiments using linearly polarized intense 60 fs laser pulses were conducted for structural characterization of three dichloroethylene (DCE) isomers, 1,1-DCE, cis-1,2-DCE, and trans-1,2-DCE. Under relatively low laser intensity at 1.8 × 1014 W/cm2, mass-resolved momentum imaging (MRMI) for selected fragment ions of 35Cl+ and C2+ revealed different patterns for the three isomers. The C2+ ion fragmented from multiply charged trans-1,2-DCE was forced to leave perpendicularly to the direction of the laser polarization, due to recoil forces from adjacent cations. In contrast, the fast ions of C2+ from cis-1,2-DCE exhibited an isotropic distribution, whereas the fast ions of C2+ from 1,1-DCE recoiled along the laser polarization together with the slow C2+ ions, and thereby distinction of the three isomers was demonstrated. Coulomb explosion occurs predominantly at specific orientation, which is useful for potential applications of MRMI analysis to molecular structure assays.

Water‐Resistant Lead‐Free Perovskitoid Single Crystal for Efficient X‐Ray Detection

AbstractDespite the rapid progress of hybrid organic–inorganic halide perovskites in optoelectronic applications, their water resistance is still limited because of the interaction of both the organic and inorganic components with water molecules. In this study, a cation engineering protocol to obtain a material with inherent high water resistance by incorporating benzamidinium (BAH) cations into the bismuth halide framework is developed. Analysis of the crystal structure indicates that (BAH)BiI4 exhibits a molecular 1D perovskitoid structure with an edge‐sharing mode and strong noncovalent interactions within the crystal, including I•••I interaction, hydrogen bonding, and π–π stacking between adjacent BAH cations. Such strong noncovalent interactions provide excellent water resistance, with negligible decomposition of crystals during water soaking for two months. The feasibility of the (BAH)BiI4 crystal for X‐ray detection, with a sensitivity as high as 1181.8 µC Gyair−1 cm−2 and a detection limit below 77 nGyair s−1 under 50 V bias is further demonstrated. Such good values are due mainly to efficient charge transport along the π–π stacking between neighboring BAH cations and I•••I interactions between adjacent inorganic chains. These findings provide a new approach to improve the water resistance of perovskite/perovskitoid optoelectronic devices.

Tetra-μ-acetato-κ8 O:O'-bis-[(3-chloro-pyridine-κN)ruthenium(II,III)](Ru-Ru) hexa-fluorido-phosphate 1,2-di-chloro-ethane monosolvate.

The title compound, [Ru2(μ-O2CCH3)4(C5H4ClN)2]PF6·C2H4Cl2, was obtained via a rapid substitution reaction of 3-chloro-pyridine for water in [Ru2(μ-O2CCH3)4(H2O)2]PF6 in 2-propanol and subsequent crystallization from a di-chloro-ethane solution. The cationic diruthenium(II,III) tetra-acetate core lies on a crystallographic inversion center with Ru-Ru and Ru-N bond lengths of 2.2738 (3) and 2.2920 (17) Å, respectively. The Ru-Ru-N bond angle is close to linear at 176.48 (4)°, and a significant π-stacking inter-action of 3.5649 (16) Å is seen between overlapping pyridine rings of adjacent cations.

Structure, charge density, and Hirshfeld surface analysis of proton transfer complex 2‐amino‐4‐methylpyridinium 2‐(3‐methylphenyl)‐acetate

AbstractThe compounds m‐Tolylacetic acid and 2‐amino‐4‐Picoline were used as a precursor to synthesize the molecular complex 2‐amino‐4‐methylpyridinium 2‐(3‐methylphenyl)‐acetate by means of proton transfer. High‐resolution X‐ray diffraction data were collected for the crystallized complex at 100 K. The structure was solved spherically and further an aspherical model refinement was performed using Hansen and Coppens multipole formalism. Topological properties using AIM analysis were carried out for the title compound to understand the atom–atom interactions and the strength of the bond. The structure exhibits interesting patterns of N–H…O and C–H…O hydrogen bonds. A pair of N–H…O hydrogen bonds links the anion and cation of the molecular complex generating an R22(8) ring motif. These ring motifs are linked to adjacent anions and cations through another intermolecular N–H…O hydrogen bond generating a bifurcated R22(8)ring motif. Hirshfeld surface analysis was carried out to understand the types of inter‐molecular interactions and their strengths.

Insight into the Enhanced Charge Transport in Quasi-2D Perovskite via Fluorination of Ammonium Cations for Photovoltaic Applications.

Fluorinated spacer cations in quasi-2D (Q-2D) perovskites have recently been demonstrated to improve the Q-2D perovskite solar cell (PSC) performance. However, the underlying mechanism of fluorination of organic cations on the improvement is still unclear. Here, using fluorinated benzylammonium (named F-BZA) as a spacer cation in Q-2D Ruddlesden-Popper (RP) perovskites, we deeply investigate the effect of fluorination of organic cations on perovskite crystallization and intermolecular interactions for improving the charge transport and device performance. It is found that fluorination of spacer cations can slow down the crystallization rate of perovskites, resulting in vertically aligned large grains. Moreover, the interaction between the adjacent spacer cations is further enhanced, constructing a new faster charge-transport channel with a lifetime of 77 ps. Accordingly, the carrier mobility is improved by an order of magnitude and a power conversion efficiency (PCE) of 16.82% is achieved in much more stable F-BZA-based Q-2D RP PSCs, 35% higher than that of BZA-based devices (12.39%). Our results elucidate the mechanism and its importance of fluorinating spacer cations for high-performance Q-2D PSC development.