Search

Lead free and environment friendly, light absorbing material is in high demand for the photovoltaic perovskite solar cell devices. The double perovskite La2NiMnO6 have the centre of attention for this demand. The present review is focused to discuss briefly the progress and challenges in the structural and magnetic properties of La2NiMnO6 in bulk, nano and thin film phases. The structural changes of La2NiMnO6 are highly interesting and have the direct correlation with the magnetic properties. On the basis of these transformations in the structure, efforts have been made to discuss several scientific progresses into technical novelties. This short review article is critically dedicated on reviewing the progresses, openings, and upcoming challenges in perovskite solar cell devices.

In recent years, metal halide perovskites (MHPs) have attracted attention as semiconductors that achieve desirable properties for optoelectronic devices. However, two challenges—instability and the regulated nature of Pb —remain to be addressed with commercial applications. The development of Pb-free halide double perovskite (HDP) materials has gained interest and attention as a result. This family offers potential in the field of optoelectronic devices through flexible material designs and compositional adjustments. We highlight recent progress and development in halide double perovskites and encompass the synthesis, optoelectronic properties, and engineering of the electronic structures of these materials along with their applications in optoelectronic devices. Computational and data-driven statistical methods can also be used to explore mechanisms and discover promising candidate double perovskites.

Successful strategies for the design of crystalline materials with useful function are frequently based on the systematic tuning of chemical composition within a given structural family. Perovskites with the formula ABX3, perhaps the best-known example of such a family, have a vast range of elements on A, B, and X sites, which are associated with a similarly vast range of functionality. Layered double perovskites (LDPs), a subset of this family, are obtained by suitable slicing and restacking of the perovskite structure, with the additional design feature of ordered cations and/or anions. In addition to inorganic LDPs, we also discuss hybrid (organic-inorganic) LDPs here, where the A-site cation is a protonated organic amine. Several examples of inorganic LDPs are presented with a discussion of their ferroic, magnetic, and optical properties. The emerging area of hybrid LDPs is particularly rich and is leading to exciting discoveries of new compounds with unique structures and fascinating optoelectronic properties. We provide context for what is important to consider when designing new materials and conclude with a discussion of future opportunities in the broad LDP area.

The highest power conversion efficiency (PCE) for organic-inorganic perovskite solar cells based on lead is reported as 25.2% in 2019. Lead-based hybrid perovskite materials are used in several photovoltaics applications, but these are not highly favored due to the toxicity of lead and volatility of organic cations. On the other hand, hybrid lead-free double perovskite has no such harm. In this research study, SCAPS numerical simulation is utilized to evaluate and compare the results of perovskite solar cell based on double perovskite FA 2 BiCuI 6 and standard perovskite CH 3 NH 3 PbI 3 as an active layer. The results show that the power conversion efficiency obtained in the case of FA 2 BiCuI 6 is 24.98%, while in the case of CH 3 NH 3 PbI 3 , it is reported as 26.42%. This indicates that the hybrid organic-inorganic double perovskite FA 2 BiCuI 6 has the ability to replace hybrid organic-inorganic perovskite CH 3 NH 3 PbI 3 to expand next-generation lead-free harmless materials for solar cell applications.

We have synthesized Gd$_{2}$FeCrO$_{6}$ (GFCO) double perovskite which is crystallized in a monoclinic structure with P2$_{1}/$n space group. The UV-visible and photoluminescence spectroscopic analyses confirmed its direct bandgap semiconducting nature. Employing experimentally obtained structural parameters in first-principles calculation, we report the spin-polarized electronic band structure, charge carrier effective mass, density of states, electronic charge density distribution and optical absorption property of the GFCO double perovskite. The effects of on-site d-d Coulomb interaction energy (U$_{eff}$) on the electronic and optical properties were investigated by applying a range of Hubbard U$_{eff}$ parameters from 0 to 6 eV to the Fe-3d and Cr-3d orbitals within the generalized gradient approximation (GGA) and GGA+U methods. When we applied U$_{eff}$ in the range of 1 to 5 eV, both the up-spin and down-spin band structures were observed to be direct. The charge carrier effective masses were also found to enhance gradually from U$_{eff} =$ 1 eV to 5 eV, but, these values were anomalous for U$_{eff} =$ 0 and 6 eV. These results suggest that U$_{eff}$ should be limited within the range of 1 to 5 eV to calculate the structural, electronic and optical properties of GFCO double perovskite. We observed that considering U$_{eff} =$ 3 eV, the theoretically calculated optical band gap 1.99 eV matched well with the experimentally obtained value 2.0 eV. The outcomes of our finding imply that the U$_{eff}$ value of 3 eV most accurately localized the Fe-3d and Cr-3d orbitals of GFCO keeping the effect of self-interaction error from the other orbitals almost negligible. Therefore, we may recommend U$_{eff} =$ 3 eV for first-principles calculation of the electronic and optical properties of GFCO double perovskite that might have potential in photocatalytic and related solar energy applications.

The growing demands for optical anti-counterfeiting technology require the development of new environmentally friendly materials with single component, multimodal fluorescence and high stability. Herein, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 lead-free double perovskite material is reported as an efficient multimodal luminescence material with excitation-wavelength-dependent emission. When excited by 360 nm UV light, dual-emission is observed at 455 and 560 nm, which comes from the 3P1-1S0 transition of Sb3+ ions and self-trapped excitons (STEs), respectively. Under the 320 nm UV lamp, the microcrystals show only a blue emission centered at 455 nm. Therefore, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 double perovskite emits blue and yellow lights under the 320 and 360 nm UV lamp, respectively. Moreover, the obtained double perovskite shows a high PLQY up to 41% and excellent stability against both air and high temperature, which make it a promising anti-counterfeiting material.

The competitive effects of Fe/Mo anti-site defect (ASD) concentration and grain boundary (GB) property on the magnetoresistance (MR) behavior of Sr2FeMoO6 (SFMO) double perovskite are investigated. Two SFMO samples with different ASD concentrations (31% and 14%) were prepared by controlling the different sintering temperature, and then, they were performed several GB modifying treatments. While the ASD remain unchanged, the MR values of both samples were appreciably enhanced since more than thousand times of resistivity had been increased after GB modifying. When compared samples that under the same soaking treatments, the more disorder sample (ASD = 31%) always showed the lower MR value than the ordered (ASD = 14%), regardless of its stronger GB strength. This suggests that the negative effect of ASD always plays an important role in MR behavior and this adverse effect is hardly offset by the increased positive effects of its GB property.

The optical and thermometric properties of bismuth (Bi) and ytterbium (Yb) codoped double perovskite Cs2Ag0.6Na0.4InCl6 microcrystals (MCs) are investigated, which possess high photoluminescence qu...

Lead halide perovskite nanocrystals (NCs) have been recognized as a rather competitive candidates for potential advanced optoelectronic applications. But the toxicity of lead and the intrinsic instability are the key concerns for their large-scale commercialization. For addressing these tricky issues, we synthesized lead-free all-inorganic Cs2AgBiBr6 double perovskite NCs adopting a facile hot injection approach. The as-prepared NCs could keep their structure stable either in air for more than two months or being heated at 300 °C in ambient atmosphere for 3 h. Moreover, Cs2AgBiBr6 NCs were investigated for photocatalytic NO removal under visible-light irradiation, achieving an exciting removal rate of 97%, which is much higher than the previous reports as we know. In addition, the Cs2AgBiBr6 NCs demonstrated outstanding recyclability for at least four cycles in NO removal. The photocatalytic mechanism of Cs2AgBiBr6 NCs was further proposed. This investigation offers a new environmental photocatalyst to purify the air.

CaMnFeTaO6 has been synthesized at 1200 °C under 10 GPa pressure. Powder neutron diffraction shows that CaMnFeTaO6 adopts a double double perovskite structure (tetragonal space group P42/n, lattice parameters a = 7.683(3) and c = 7.685(7) Å) with cation disorder at all transition-metal sites. Magnetization measurements reveal an apparent ferro- or ferrimagnetic transition at Tm1 = 51 K and a susceptibility peak at Tm2 = 20 K, but no long-range magnetic order is observed by neutron diffraction down to 1.5 K. This is attributed to the formation of superparamagnetic clusters of ferrimagnetically ordered spins below Tm1 that freeze into a cluster spin glass at Tf = Tm2. ac magnetization measurements confirm the cluster spin glass ground state. Disorder from the substitution of Fe2+ for Mn2+ and Fe3+/Ta5+ inversion disrupts the network of superexchange interactions leading to the cluster spin glass ground state, in contrast to other P42/n double double perovskites where long-range magnetic order is stabilized.

Perovskites are of great technological and geological importance, in large part, due to their considerable compositional and structural flexibility. However, the formation of perovskites with neutr...

Double perovskite ceramics Sr2FeMoO6–δ having different amount of antisite disordering and oxygen content are prepared by the solid-phase reaction method using SrFeO2.52(3) and SrMoO4 initial reagents. X-ray and neutron diffraction techniques are used to estimate a modification in the structural parameters as a function of oxygen content and B–site cationic ordering. Reduction of oxygen content leads to an increase in the unit cell volume, which is mainly associated with an elongation of c –parameter of the tetragonal unit cell and relative expansion of the chemical bonds between Mo/Fe ions and apical oxygen ions. Superstructural ordering observed for the compounds causes a decrease in the unit cell volume, which is accompanied by a reduction in the length of the Mo/Fe – O bonds, located in the basal plane of oxygen octahedra. This modification of the unit cell parameters notably affects a character of the exchange interactions formed between B–site ions thus allowing to control magnetic and transport properties of Sr2FeMoO6–δ ceramics. It is found that comprehensive approach allows a consistent understanding of much debated structural/magnetic behaviors of double perovskite Sr2FeMoO6–δ systems, opening a venue for designing reliable devices based on the half-metallic double perovskite materials.

The role of A-sited elements in double perovskite colossal dielectric LiCuNb3O9 has been analyzed by replacing the Cu ions with Li ions. Structural analysis revealed the presence of Jahn-Teller effect because of the Cu ions. Two thermally activated relaxations have been observed: the lower temperature one has been assigned to be a polaronic relaxation following Mott variable-range-hopping mechanism. Impedance analysis and humidity sensitive test proved that the higher temperature one is a Maxwell-Wagner relaxation. Our work highlights that the polaronic hopping is responsible for the colossal dielectric permittivity behavior of LiCuNb3O9.

Cs2AgBiBr6 is a promising metal halide double perovskite offering the possibility of efficient photovoltaic devices based on lead-free materials. Here, we report on the evolution of photoexcited charge carriers in Cs2AgBiBr6 using a combination of temperature-dependent photoluminescence, absorption and optical pump–terahertz probe spectroscopy. We observe rapid decays in terahertz photoconductivity transients that reveal an ultrafast, barrier-free localization of free carriers on the time scale of 1.0 ps to an intrinsic small polaronic state. While the initially photogenerated delocalized charge carriers show bandlike transport, the self-trapped, small polaronic state exhibits temperature-activated mobilities, allowing the mobilities of both to still exceed 1 cm2 V–1 s–1 at room temperature. Self-trapped charge carriers subsequently diffuse to color centers, causing broad emission that is strongly red-shifted from a direct band edge whose band gap and associated exciton binding energy shrink with increasing temperature in a correlated manner. Overall, our observations suggest that strong electron–phonon coupling in this material induces rapid charge-carrier localization.

When the stakes are doubled in a wager, a player must correctly place two consecutive bets to win, but the payout is larger. Similarly, two B sites in combination dictate the properties of A2 BB'X6 (A=monocation, X=halide) double perovskites. Correctly picking two B sites is more challenging than picking just one, as in the AI BII X3 single perovskites, but the options are greater and, we believe, the rewards are higher when the stakes are doubled. In this Minireview, we emphasize fundamental aspects of halide double perovskites to provide a foundation for interested readers to explore this extraordinary class of materials. In particular, we highlight the differences and similarities between double and single perovskites and describe how the double perovskite structure potentially offers greater control over photophysical properties.

The technique of coupling cation ordering with other microscopic degrees of freedom was employed to induce magnetic polar phenomena within the materials belonging to the double perovskite oxide fam...

We have investigated the effect of copper substitution on the structure, cation valence, and magnetic properties of the double perovskite La2MnCoO6. La2Mn1–xCuxCoO6 (0 ≤ x ≤ 0.4) were synthesized b...

Perovskite oxides continue to attract huge interest due to their fascinating and wide-ranging properties for diverse applications. The tunability of these properties may be further enhanced by incr...

In this work, new double perovskite Tb2ZnMnO6 nanoparticles were successfully synthesized by a sol–gel auto combustion method.

In view of iridium's scarceness and high cost, Ir-containing catalysts for water electrolyzers should have low loadings and maximal utilization. Here, we studied low-Ir-content, highly active, double perovskites (Sr2MIrO6, M = Ni, Co, Sc and Fe) for the oxygen evolution reaction (OER) in acid combining electrochemical experiments, DFT, and advanced characterization techniques. The initial OER performance depends on Ir's oxidation state and the geometric features of IrO6 frameworks, which are tuned by the choice of M. Higher oxidation states, particularly Ir6+, enhance the OER activity: Sr2NiIrO6 and Sr2CoIrO6 display potentials of ∼1.53 V at 10 mA cm−2, comparable to the best Ir-based catalysts in the literature. However, because of their less symmetric structures, perovskites with Ir6+ are less stable, prone to surface reconstruction and their cations leach under OER conditions. These results show that improved iridium-based OER electrocatalysts in acid can be designed by balancing their activity and stability.

A two-dimensional (2D) Dion–Jacobson (DJ) lead-free semiconductive hybrid double perovskite (HDP) [(3AMPY)2AgBiI8·H2O] (3AMPY = 3-(aminomethyl) pyridinium) (1) has been reported, which shows an attractive narrow band gap of 1.86 eV. Importantly, 1 is the first 2D DJ lead-free environmental friendly HDP constructed by an aromatic diammonium cation with high stability in humid conditions.

The physical properties of the double perovskite A2BB'O6 are closely related to the B-site cationic arrangement, which directly affects the crystal morphology, magnetic coupling and electronic structure. Herein, the impact of B-site antisite defects on the magnetic and electronic properties of double perovskite Pb2FeOsO6 has been investigated using spin-polarized first-principles calculations. Our calculations demonstrate that B-site ordered Pb2FeOsO6 is a ferrimagnetic semiconductor with the saturated magnetic moment of ~2.27 μB f.u.−1, mainly generated from B-site Fe and B′-site Os antiferromagnetic coupling. With the introduction of B-site antisite defects, the crystal lattices nearly maintain the original structure of the ordered Pb2FeOsO6, although the internal atomic arrangements are reconstructed. Nevertheless, the saturated magnetic moment is sharply reduced in Fe/Os disordered configurations, which originates from the additional Os–Os and Fe–Fe antiferromagnetic coupling, and consequently induces Os–Os, Os–Fe and Fe–Fe spins interaction competition. Further electronic structure analyses indicate that the B-site antisite defects do not alter the semiconducting performance of Pb2FeOsO6. Our study sharpens the understanding of the effects of cationic ordering on the physical properties of double perovskites and provides an alternative avenue for tailoring their characteristics.

Recently, lead-free double perovskites of Cs2AgBiBr6 have attracted worldwide attention as a promising candidate for eco-friendly photovoltaics because of their intrinsic environmental stability and highly desired low toxicity in comparison with conventional lead halide counterparts. However, their power conversion efficiency (PCE) is still far lower than that of lead halide perovskites, which is mainly associated with their poor quality films. Herein, we report a facile process via precursor engineering based on the BiBr3(DMSO)2 adduct solution to produce high-coverage and smooth Cs2AgBiBr6 films with large grains. As a result, the as-constructed planar solar cells deliver a champion PCE of 0.73%, which exhibits an enhancement of over 40% in PCE compared to that of the control sample, suggesting their potential to be applied in lead-free bismuth-based optoelectronic devices.

Double perovskite oxides with d8-d3 electronic configurations are expected to be ferromagnetic from the Goodenough-Kanamori rules, such as ferromagnetic La2NiMnO6. In search of new ferromagnetic insulators, double perovskite Ba2NiIrO6 was successfully synthesized by high-pressure and high-temperature methods (8 GPa and 1573 K). Ba2NiIrO6 crystallizes in a cubic double perovskite structure (space group: Fm3m), with an ordered arrangement of NiO6 and IrO6 octahedra. X-ray absorption near-edge spectroscopy confirms the nominal Ni(II) and Ir(VI) valence states. Ba2NiIrO6 displays an antiferromagnetic order at 51 K. The positive Weiss temperature, however, indicates that ferromagnetic interactions are dominant. Isothermal magnetization curves at low temperatures support a field-induced spin-flop transition.

Halide double perovskites have allowed the significant expansion of the possible metals and oxidation states in halide perovskites. Further, they have shown some remarkable properties and applicati...

Halide perovskites offer great promise for optoelectronic applications, but stability issues continue to hinder their implementation and long-term stability. The stability of all-inorganic halide p...

Halide double perovskites have emerged as remarkable semiconductors owing to their nontoxicity and superior optoelectronic features. Despite recent exciting progress, halide double perovskites with...

Organic-inorganic metal halide perovskites (most notably CH3 NH3 PbI3 ) have demonstrated remarkable physical attributes for photovoltaic and diverse optoelectronic applications, whereas concerns about toxicity owing to the use of lead in the chemical composition still motivate further exploration of new, nontoxic candidates. Lead-free halide double perovskites (HDPs), designed by the rational chemical substitution of Pb2+ with other nontoxic candidate elements, have recently attracted interest as a fascinating alternative to their Pb-based counterparts. Herein, recent advances in crystal structures, physical properties, and versatile optoelectronic applications of lead-free HDPs, such as solar cells, photodetectors, X-ray detectors, and light-emitting diodes, are reviewed. Perspectives to improve the physical and photoelectric properties of existing HDP materials are also discussed and will favor future development of new, lead-free HDP candidates.

The structural, mechanical, electronic and optical properties of double perovskite Cs2SnBr6 have been measured by density functional theory (DFT) calculations. The calculated value of lattice parameter is perfectly tailored with the experimental data. The material shows ductile behavior by Paugh’s ductility index (B/G) at ambient condition. The anisotropic nature of this compound is endorsed by the calculation of Zener anisotropy factor. The direct band gap semiconducting nature with the value of gap is 1.33 eV using PBE potential is also corroborated by electronics properties. Eventually, different optical properties of Cs2SnBr6 such as dielectric constants, refractive index, conductivity, absorption, reflectivity and loss function have been observed and disclose for radiation up to 20 eV. Finally the optical properties corroborate the optoelectronic applications of this compound as all as elite candidate for photovoltaic perovskite solar cells.

The aim of this research work is to investigate the structural, mechanical, electronic and optical properties of double perovskite Rb2SnBr6 by density functional theory (DFT) calculations. The calculated lattice parameter is in sensible agreement with the on the market experimental information. From Paugh’s ductility index (B/G), it shows that Rb2SnBr6 is brittle at ambient conditions. The Zener anisotropy factor confirms the anisotropic nature of this compound. The calculated energy band structures indicate that Rb2SnBr6 is a direct band gap semiconductor, with the band gap of 1.228 eV using PBE potentials. In this work, the optical properties such as dielectric constants, refractive index, conductivity, extinction coefficient, loss function, and reflectivity have been studied and reported for radiation up to 20 eV. It is found that the reflectivity is about 50% in the ultraviolet (UV) region regions up to ~11 eV of incident radiation in the ultraviolet region.

Here, we present the synthesis and crystal structure of Rb3InCl6 prepared from air stable reagents via a two-step process that proceeds through the intermediate Rb2InCl5·H2O. Rb3InCl6 crystallizes ...

All-inorganic double perovskites (elpasolites) are a promising potential alternatives to lead halide perovskites in optoelectronic applications. Although halide mixing is a well-established strateg...

Lead halide perovskite has in recent years gained widespread interest due to its excellent physical and chemical properties, as well as superior optoelectronic performance. However, some restrictio...

Floating gate transistor photomemory (FGTPM) has been regarded as one of the most prospective nonvolatile photomemory devices because of its compatibility with transistor-based circuits, nondestruc...

In this study, the oxygen reduction activity of PrBaCo2O5+δ (PBC) double perovskite is remarkably enhanced by rationally tuning the calcination temperatures of the cathode precursor for solid oxide fuel cells (SOFCs). Effects of the calcination temperatures on the phase structure, microstructure, surface area and oxygen reduction reaction (ORR) activity of PBC cathode is systematically investigated. The cathode with optimized calcination temperature (900 °C, PBC-900) shows excellent activity and stability for ORR at 600 °C in terms of area specific resistances (ASRs). A distinctive low ASR of 0.068 Ω cm2 is obtained at 600 °C for PBC-900, which is 92.6%, 34.6% and 15.0% lower than PBC-800, PBC-1000 and PBC-1100, respectively. After operating for 250 h in air at 600 °C, the ASR value of PBC-900 is not significantly reduced. Furthermore, a single cell with PBC-900 cathode delivers attractive peak power density of 1.60 W cm−2 at 600 °C. The present study suggests that the ORR activity of PBC cathode can be greatly boosted by rationally tailoring the calcination temperatures, which may bring new avenue for the design of highly active cathodes for SOFCs.

Lead-free double perovskite phosphors are promising alternatives to lead halide perovskites for wide uses in optoelectronic applications, but suffer from a low quantum efficiency. Here, we propose ...

Understanding the photoinduced carrier dynamics in Cs2AgBiBr6 double perovskites is essential for their application in optoelectronic devices. Herein, we report an investigation on the temperature-...

The solid-state magnetic cooling (MC) relying on magnetocaloric effect (MCE) of magnetic materials is recognized as a promising energy efficiency and environmentally friendly technology. However, there is still a large gap between the fundamental materials in the laboratory developing stage and the practically realizable applications. In this paper, a new series of B-site ordered RE2ZnMnO6 (RE = Gd, Dy and Ho) perovskites are successfully fabricated, and their structural and magnetic properties together with the cryogenic magnetocaloric performances are studied in detail. All the RE2ZnMnO6 compounds are found to crystallize in the B-site ordered orthorhombic (double perovskites) structure with the space group of P121/C1. The magnetic ground state are confirmed to be a ferromagnetic (FM) coupling for Gd2ZnMnO6, whereas, ferrimagnetic (FIM) coupling for Dy2ZnMnO6 and Ho2ZnMnO6 based on the magnetic measurements and first principle calculations. The ordering temperatures (TM) are determined to be ~6.4 K for Gd2ZnMnO6, ~10.4 K for Dy2ZnMnO6, and ~6.8 K for Ho2ZnMnO6, respectively. Furthermore, several vital parameters for determining the magnetocaloric performances including -ΔSMmax (magnetic entropy change peak values), TEC(2) (temperature-averaged magnetic entropy change) and RCP (relative cooling powers) are evaluted to be 15.17, 14.44 J/(kgK) and 226 J/kg for Gd2ZnMnO6, 8.32, 8.17 J/(kgK) and 208 J/kg for Dy2ZnMnO6, and 13.19, 12.68 J/(kgK) and 246 J/kg for Ho2ZnMnO6, with the field change ΔH = 50 kOe, respectively. It is worthly noted that Gd2ZnMnO6 exhibits relatively great magnetocaloric performances below 10 K, which suggests that Gd2ZnMnO6 is a competitive candidate for cryogenic magnetic cooling.

Engineering halide double perovskite (A2M+M3+XVII6) by mixing elements is a viable way to tune its electronic and optical properties. In spite of many emerging experiments on halide double perovski...

Lead-free halide double perovskites (DPs) have attracted great attention due to their stability, nontoxicity and good photophysical property. In this work, we report a new, small-bandgap Cs2CuSbCl6...

Intrinsic broadband photoluminescence (PL) of self-trapped excitons (STEs) are systematically studied in lead-free double perovskite nanocrystals (NCs). It is clarified that bandgap (direct/indirect) has important influence on the PL properties of STEs: indirect bandgap NCs exhibit strong exciton-phonon coupling which results in non-radiative STEs, while direct bandgap NCs exhibit moderate exciton-phonon coupling, inducing bright STE PL. Furthermore, by alloying K+ and Li+ ions in Cs2AgInCl6 NCs, the NCs exhibit broadband white-light emission. Charge-carrier dynamics study indicates that the efficient white-light emission originates from the further suppressed non-radiative processes of the STEs in the direct bandgap structure. This work may deepen the understanding of STEs and guide the design of high-performance lead-free perovskites.

The crystal structures of various types of perovskite halide compounds were summarized and described. Atomic arrangements of these perovskite compounds can be investigated by X-ray diffraction and transmission electron microscopy. Based on the structural models of basic perovskite halides, X-ray and electron diffractions were calculated and discussed to compare with the experimental data. Other halides such as elemental substituted or cation ordered double perovskite compounds were also described. In addition to the ordinary 3-dimensional perovskites, low dimensional perovskites with 2-, 1-, or 0-dimensionalities were summarized. The structural stabilities of the perovskite halides could be investigated computing the tolerance and octahedral factors, which can be useful for the guideline of elemental substitution to improve the structures and properties, and several low toxic halides were proposed. For the device conformation, highly crystalline-orientated grains and dendritic structures can be formed and affected the photo-voltaic properties. The actual crystal structures of perovskite halides in the thin film configuration were studied by Rietveld analysis optimizing the atomic coordinates and occupancies with low residual factors. These results are useful for structure analysis of perovskite halide crystals, which are expected to be next-generation solar cell materials.

Cs2AgBiBr6 double perovskites are intensely investigated as lead-free, stable alternatives to organic lead halide perovskites. In this contribution, we revise the vibrational modes of Cs2AgBiBr6 and show that Raman spectroscopy is well suited for the detection of common secondary phases such as Cs3Bi2Br9. The combined Raman analysis at pre-, near- and non-resonant conditions allows us to extract the four vibrational modes of Cs2AgBiBr6 to unprecedented detail, the most intense one at 177.3 cm-1. The experimental results are in good agreement with theoretical density functional theory calculations. In addition, we monitor the decomposition of Cs2AgBiBr6 into Cs3Bi2Br9 at temperatures above 255 °C.

In this study, Ba2Fe1−xNixMoO6(0.0 ≤ x ≤ 0.2) (BFNMO) double perovskite materials were prepared by sol–gel method in the H2/Ar atmosphere. The cubic structure of BFNMO was identified by XRD studies. The values of lattice parameters were marginally improved by Ni dopant. The saturation magnetization was set up to be abridged at temperatures 5 and 300 K by doping Ni in Ba2FeMoO6. The Curie temperature of BFNMO was also somewhat amplified by Ni content. The magnetoresistance studies of BFNMO showed up different behaviors at temperatures 5, 150, and 300 K with Ni composition. The value of magnetoresistance rose at 300 K and decreased at 5, 150 K by doping Ni in Ba2FeMoO6. The high value of MR (%) is − 16.75 for composition x = 0.0 at temperature 5 K and magnetic field 80 kOe in the BFNMO.

As an alternative to lead halide perovskites, various types of lead-free perovskites have been recently studied for optoelectronic materials. This paper reports the synthesis of highly phase-pure C...

Concerns about the toxicity of lead-based perovskites have aroused great interest for the development of alternative lead-free perovskite-type materials. Recently, theoretical calculations predict that Pb2+ cations can be substituted by a combination of Cu2+ and Sb3+ cations to form a vacancy-ordered layered double perovskite structure with superior optoelectronic properties. However, accessibilities to this class of perovskite-type materials remain inadequate, hindering their practical implementations in various applications. Here, we report the first colloidal synthesis of Cs4CuSb2Cl12 perovskite-type nanocrystals (NCs). The resulting NCs exhibit a layered double perovskite structure with ordered vacancies and a direct band gap of 1.79 eV. A composition-structure-property relationship has been established by investigating a series of Cs4CuxAg2-2xSb2Cl12 perovskite-type NCs (0 ≤ x ≤ 1). The composition induced crystal structure transformation, and thus, the electronic band gap evolution has been explored by experimental observations and further confirmed by theoretical calculations. Taking advantage of both the unique electronic structure and solution processability, we demonstrate that the Cs4CuSb2Cl12 NCs can be solution-processed as high-speed photodetectors with ultrafast photoresponse and narrow bandwidth. We anticipate that our study will prompt future research to design and fabricate novel and high-performance lead-free perovskite-type NCs for a range of applications.

Double perovskites have recently emerged as possible alternatives to lead-based halide perovskites for photovoltaic applications. In particular, Cs2AgBiBr6 has been the subject of several studies b...

Recently, layered halide double perovskites (A4MIMIIIX8) have attracted growing interest and provided a wide range of basic building blocks for fabricating vertical and lateral heterostructures (LH...

Lead (Pb) halide perovskites have witnessed highly promising achievements for high-efficiency solar cells, light-emitting diodes (LEDs), and photo/radiation detectors due to their exceptional optoelectronic properties. However, compound stability and Pb toxicity are still two main obstacles towards the commercialization of halide perovskite-based devices. Therefore, it is of substantial interest to search for non-toxic candidates with comparable photophysical characteristics. Metal-halide double perovskites (MHDPs), A2BBʹX6, are recently booming as promising alternatives for Pb-based halide-perovskites for their non-toxicity and significantly enhanced chemical and thermodynamic stability. Moreover, this family exhibits rich combinatorial chemistry with tuneable optoelectronic properties and thus a great potential for a broad range of optoelectronic/electronic applications. Herein, we present a comprehensive review of the MHDPs synthesized so far, and classified by their optical and electronic properties. We systematically generalize their electronic structure by both theoretical and experimental efforts to prospect the relevant optoelectronic properties required by different applications. The progress of the materials in various applications is explicated in view of the material structure-function relationship. Finally, a perspective outlook to improve the physical and optoelectronic properties of the materials is proposed aiming at fostering their future development and applications.

High-quality BFCO films with smooth morphology were deposited on (001)-oriented single crystal substrates by pulsed-laser deposition. The perfect ferroelectric nature of the BFCO films were probed by PFM and electrical P-E hysteresis measurements and the obtained saturated remeanent polarization value reaches up to 60 μC/cm2. Besides, BFCO films show relatively low bandgap of 2.5 eV, can absorb the sunlight and convert the solar energy to electrically energy effectively. A photocurrent of 1.2 mA/cm2 and an open-circuit voltage of about 0.53 V were obtained under AM1.5G illumination. The results mainfest the BFCO a potiential material for multifunctional devices, especially for photovoltaics.