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Low‐dimensional hybrid halide perovskites represent a promising class of materials in optoelectronic applications because of strong broad self‐trapped exciton (STE) emissions. However, there exists a limitation in designing the ideal A‐site cation that makes the material satisfy the structure tolerance and exhibit STE emission raised by the appropriate electron–phonon coupling effect. To overcome this dilemma, we developed an inorganic metal‐organic dimethyl sulfoxide (DMSO) coordinating strategy to synthesize a series of zero‐dimensional (0D) Sb‐based halide perovskites including Na3SbBr6·DMSO6 (1), AlSbBr6·DMSO6 (2), AlSbCl6·DMSO6 (3), GaSbCl6·DMSO6 (4), Mn2Sb2Br10·DMSO13 (5) and MgSbBr5·DMSO7 (6), in which the distinctive coordinating A‐site cation [Am‐DMSO6]n+ efficiently separate the [SbXz] polyhedrons. Advantageously, these materials all exhibit broadband‐emissions with full widths at half maxima (FWHM) of 95–184 nm, and the highest photoluminescent quantum yield (PLQY) of 3 reaches 92%. Notably, compounds 2–4 are able to remain stable after storage of more than 120 d. First‐principles calculations indicate that the origin of the efficient STE emission can be attributed to the localized distortion in [SbXz] polyhedron upon optical excitation. Experimental and calculational results demonstrate that the proposed coordinating strategy provides a way to efficiently expand the variety of novel high‐performance STE emitters and continuously regulate their emission behaviors. For low‐dimensional perovskites exhibiting broad‐band emission by self‐trapped excitons (STEs), satisfying the structure tolerance while exhibiting strong emission is a roadblock. By designing a unique cation [Am‐DMSO6]n+, a series of zero‐dimensional perovskites as AmSbXz·DMSOi has been synthesized, boosting the variety of antimony‐based STE‐emitting perovskites with excellent photoluminescent properties such as high photoluminescent quantum yields and adjustable correlated color temperature range.

Metal halide perovskites and their derived materials have garnered significant attention as promising materials for solar cell and light‐emitting applications. Among them, 0D perovskites, characterized by unique crystallographic/electronic structures with isolated metal halide octahedra, exhibit tremendous potential as light emitters with self‐trapped exciton (STE). However, the modulation of STE emission characteristics in 0D perovskites primarily focuses on regulating B‐ or X‐site elements. In this work, a lead‐free compound, Sb3+‐doped ((C2H5)2NH2)3InCl6 single crystal, which exhibits a high photoluminescence quantum yield, is synthesized, and with increasing temperature, the A‐site organic cations undergo a transition from an ordered configuration to a disordered one, accompanied by a redshift in the STE emission. Furthermore, Hirshfeld surface calculations reveal that high temperatures enhance the thermal vibrations of SbCl63− clusters and the octahedra distortion, which are responsible for the redshift. Since this thermally triggered transition of A‐site order is reversible, it can be exploited for temperature‐sensing applications. Overall, in this work, valuable insights are provided into the role of A‐site cations in modulating STE emission and the design of efficient light emitters. In 0D perovskite Sb3+‐doped ((C2H5)2NH2)3InCl6, the A‐site organic cations undergo a transition from an ordered configuration to a disordered one as the temperature increases. This transition enhances the thermal vibrations of SbCl63− clusters and the octahedra distortion, which results in color change, i.e., redshift of wavelength, in the self‐trapped exciton emission.

HighlightsThe soft 2D material reduces the coupling strength between carriers and longitudinal optical phonons, releasing the mechanical stress of lattice vibration.The power conversion efficiency of rigid devices and flexible devices reaches 25.5% and 23.4%, respectively.This study presents experimental evidence of the dependence of non-radiative recombination processes on the electron–phonon coupling of perovskite in perovskite solar cells (PSCs). Via A-site cation engineering, a weaker electron–phonon coupling in perovskite has been achieved by introducing the structurally soft cyclohexane methylamine (CMA+) cation, which could serve as a damper to alleviate the mechanical stress caused by lattice oscillations, compared to the rigid phenethyl methylamine (PEA+) analog. It demonstrates a significantly lower non-radiative recombination rate, even though the two types of bulky cations have similar chemical passivation effects on perovskite, which might be explained by the suppressed carrier capture process and improved lattice geometry relaxation. The resulting PSCs achieve an exceptional power conversion efficiency (PCE) of 25.5% with a record-high open-circuit voltage (VOC) of 1.20 V for narrow bandgap perovskite (FAPbI3). The established correlations between electron–phonon coupling and non-radiative decay provide design and screening criteria for more effective passivators for highly efficient PSCs approaching the Shockley–Queisser limit.

Ruddlesden–Popper (RP) quasi‐two‐dimensional (2D) perovskites exhibit enhanced stability compared to their three‐dimensional (3D) counterparts due to the incorporation of bulky organic spacers. However, their efficiency is relatively low owing to the large exciton binding energy and quantum confinement effects associated with these organic spacers. Herein, a diversified cation regulation strategy is developed by adjusting both the spacers and A‐site cations, achieving the fabrication of mixed 4‐fluoro‐phenethylammonium (F‐PEA+)/n‐butylammonium (BA+) and formamidinium (FA+)/methylammonium (MA+) n = 4 quasi‐2D RP perovskite solar cells. Primarily, the introduction of F‐PEA+ induces an ordered distribution of the film from low‐n to high‐n phases, resulting in enhanced crystallinity, larger grain size, fewer cracks, and voids as well as high‐quality perovskite films with preferred orientation. Furthermore, the incorporation of FA+ reduces the bandgap of the perovskite, facilitating exciton dissociation and enhancing carrier transport capabilities. Ultimately, under the cooperation effect, the obvious elevation in the efficiency of NiOx‐based (BA0.9F‐PEA0.1)2(MA0.8FA0.2)3Pb4I13 n = 4 quasi‐2D RP perovskite solar cells from 12.51 to 15.68% is achieved. Additionally, the unencapsulated devices retain 80.4% of initial efficiency after 1100 h of heating at 60 °C in ambient air with 40% relative humidity, demonstrating excellent thermal and moisture stability. The diversified cation regulation strategy by adjusting both the spacers and A‐site cations is developed, which achieving high performance quasi‐2D Ruddlesden‐Popper  perovskite solar cells via cooperation effect between F‐PEA+ and FA+.

Metal halide perovskites have been investigated for the next-generation light-emitting materials because of their advantages such as high photoluminescence quantum yield (PLQY), excellent color purity, and facile color tunability. Recently, red- and green-emissive perovskite light-emitting diodes (PeLEDs) have shown an external quantum efficiency (EQE) of over 20%, whereas there is still room for improvement for blue emissive PeLEDs. By controlling the halide compositions of chloride (Cl−) and bromide (Br−), the bandgap of perovskites can be easily tuned for blue emission. However, halide segregation easily occurrs in the mixed-halide perovskite under light irradiation and LED operation because of poor phase stability. Here, we explore the effect of A-site cation engineering on the phase stability of the mixed-halide perovskites and find that a judicious selection of low dipole moment A cation (formamidinium or cesium) suppresses the halide segregation. This enables efficient bandgap tuning and electroluminescence stability for sky blue emissive PeLEDs over the current density of 15 mA/cm2.

The rational modification of perovskite oxides (ABO 3− δ ) is essential to improve the efficiency and stability of oxygen electrolysis. Surface engineering represents a facile approach to modify perovskites for enhanced performance. Through compositional design and in situ exsolution, a Ru-doped (La 0.8 Sr 0.2 ) 0.9 Co 0.1 Fe 0.8 Ru 0.1 O 3− δ (LSCFR) perovskite anchored with CoFe(Ru) alloy particles on the surface was fabricated for oxygen evolution reaction (OER) in this work. Experimental results and calculations indicate that Ru-doping promotes the exsolution of CoFe(Ru) from the perovskite parent. Upon exsolution in the reduced atmosphere for 3 h, the catalyst (LSCFR-3) exhibited superior OER performance with an overpotential of 347 mV and a Tafel slope of 54.65 mV·dec −1 , and showed good stability in contrast to the pristine LSCFR. The exsolution of CoFe(Ru) particles, Ru doping, and the increase of surface oxygen vacancies are responsible for the enhancement of OER performance. The findings obtained in this study highlight the possibility of controlling exsolution and composition of nanoparticles by element doping and prove that in situ exsolution is an effective strategy for designing OER catalysts.

Chlorite is a ubiquitous product of metamorphism, alteration of magmatic rocks and hydrothermal processes owing to its large stability field and wide compositional range. Its composition is governed by several substitutions and has been used as a geothermometer, on the basis of empirical, semi-empirical, and thermodynamic models. As in some other phyllosilicates of petrological interest, the oxidation state of iron in chlorite may differ from the usually assumed divalent state. However, the crystal chemistry of trivalent iron in chlorite remains poorly known, and the thermodynamic properties of ferric chlorite are missing from databases used for petrological modeling. As part of an attempt to fill this gap, we present results from in situ, micrometer-scale measurements of the oxidation state of iron in various chlorite-bearing samples. X-ray absorption near-edge spectroscopy (XANES) was combined with electron probe microanalysis (EPMA) on the same crystals. Results show iron oxidation states varying from ferrous to ferric; iron is in octahedral coordination in all ferromagnesian chlorites but to ∼25% tetrahedral in the lithian chlorite cookeite (1.0 wt% Fe2O3(total)). Absolute amounts of ferric iron cover an unprecedented range (0 to ∼30 wt % Fe2O3). For highly magnesian, ferric chlorite, Fe concentrations are low and can be accounted for by Al = Fe3+ substitution. In Fe-rich samples, Fe3+ may exceed 2 atoms per formula unit (pfu, 18 oxygen basis). When structural formulas are normalized to 28 charges corresponding to the standard O10(OH)8 anionic basis, these measurements define the exchange vector of a di-trioctahedral-type substitution: 3 VI(Mg, Fe2+) = VI∎ + 2 VIFe3+, as described in earlier studies. However, structural formulas calculated on the basis of the oxygen contents actually measured by EPMA show that this trend is an artifact, due to the neglect of variations in the number of protons in the structure. Our measurements indicate increasing hydrogen deficiency with increasing Fe3+ content, up to ∼2 H+ pfu in the Fe3+-rich chlorite samples, corresponding to a net exchange vector of the type R2+ + H+ = Fe3+. These results do not support substitutions toward di-trioctahedral ferric end-members, and highlight the need for considering substitution toward an \"oxychlorite\" (i.e., H-deficient) ferric component, close to tri-trioctahedral, with an O12(OH)6 anionic basis, even in green, pristine-looking chlorite. The effects of iron oxidation and H deficiency on chlorite geothermometers were explored. They are deterring if H deficiency is ignored but, given the sensitivity of most thermometers to octahedral vacancy, the assumption FeTotal = Fe2+ is still safer than using high measured Fe3+ contents and the standard 28 charge basis, which artificially increases vacancies. In such ferric chlorites, EPMA measurement of oxygen allows a fair estimate of H content if Fe3+/Fe2+ is known; it should be more systematically implemented. For the same reasons, literature data reporting Fe3+-rich chlorite with vacancy content along the possibly artificial di-trioctahedral-type substitution should be verified. With the help of constraints from thermodynamic models, charge balance, crystal symmetry, and proton loss, a new cation site distribution is proposed for di-tri- to tri-trioctahedral chlorites in the Fe2+-Fe3+-Mg-Al-Si-O-H system, allowing a more realistic thermodynamic handling of their solid solutions.

Understanding the kinetics behavior of recalcitrant organic degradation in presence of catalyst is important in determining the reaction rates of catalysis. Therefore, this study investigates the kinetic behavior of oxidative degradation for different types of recalcitrant organic pollutants, namely as acid orange II (AOII) macropollutant and caffeine (CAF) micropollutant using B-site substituted CaMFeO3 (M = Cu, Mo, Co) perovskite catalysts. The kinetic study was analyzed based on four kinetic models which are pseudo-zero-order, first-order, second-order and BMG. Interestingly, CaCuFeO3 exhibited a unique kinetic behavior in which the reaction followed a different kinetic model: pseudo-second-order for AOII and pseudo-first-order for CAF. The reaction rate of CAF degradation in the presence of CaCuFeO3 was increased by nine orders of magnitude (k = 1.8×10-3 min-1) within 4 hr of reaction compared to pristine CaFeO3 (k = 0.2×10-3 min-1). On the contrary, CaFeO3, CaMoFeO3 and CaCoFeO3 were fitted to BMG kinetic model for the CAF degradation. These results indicate that the partial substitution of B-site cation in the perovskite structure alters the catalytic reactivity of the resultant substituted perovskite catalysts and subsequently influences the overall kinetics behavior of the oxidative degradation in both recalcitrant macro and micropollutants.

The desire for clean, affordable, and efficient energy technologies that can harvest light to generate electricity has led to recent developments in new-generation solar cells. Among them, dye-sensitized solar cells (DSSCs) have numerous merits, including low impact on the environment, facile fabrication procedures, and the associated low cost of raw materials. However, the power conversion efficiency (PCE) of DSSCs is limited by poor electron injection and high charge carrier recombination in conventional photoanode materials. This, in turn, has prompted significant research efforts to find alternative photoanode materials. In this study, we report a novel perovskite-based photoanode material (Sr 0.7 Sm 0.3 BO 2.89 ) optimised by varying the B-site using Fe or Co. To achieve this, Sr 0.7 Sm 0.3 FeO 2.89 (SSF) and Sr 0.7 Sm 0.3 CoO 2.89 (SSC) perovskites were synthesised using the ball milling method, calcined at 600 °C, and characterised using various techniques. Varying the B-site using Fe or Co significantly influenced the structure and morphology of Sr 0.7 Sm 0.3 BO 2.89 . Both perovskites revealed the formation of irregularly shaped nanoparticles with cubic and tetragonal lattices for SSF and SSC, respectively. SSF, with relatively smaller particle sizes, larger pore volumes, and better crystallinity, exhibited a relatively larger surface area (52.6 m 2  g −1 ), lower energy band gap (2.4 eV), and higher electrical conductivity (4.98 S cm −1 ) than SSC. This led to the fabrication of SSF photoanode-based DSSCs with an enhanced PCE of 6.24%, outperforming SSC-based devices by ~ 109%. Therefore, this study demonstrates that varying the B-site cations can significantly improve the physicochemical properties of perovskites for use as photoanodes in future DSSCs.

The main source of carbon entering the deep Earth is through subduction of carbonates, including CaMg(CO3)2-dolomite. We examine the high-pressure structure and stability of dolomite to understand the means through which carbon can be sequestered as it enters the deep Earth carbon cycle. Dolomite is investigated to 86 GPa using Raman spectroscopy at room temperature: this includes spectroscopic characterization of dolomite-III, a phase stable at deep mantle pressures and temperatures. Between 63-86 GPa, within the dolomite-III structure, we observe spectroscopic evidence for the evolution of a subpopulation of carbonate ions characterized by weaker C-O bonds, with anomalous pressure shifts: this abnormal bonding change is explained by the onset of a 3+1 coordination of the carbon in some of the carbonate ions in the dolomite-III structure, confirming an earlier prediction of Merlini et al. (2012). The wide suite of carbonate ions (both normal threefold and 3+1 coordinate) within this phase at the highest pressures should give rise to a large variety of cation sites; as such, dolomite-III could represent a major host for incompatible elements in the deep mantle, implying that incompatible element distribution may be closely linked to carbon cycling within the deep Earth.