Synthesis Of Perovskite Research Articles

Simultaneous Encapsulation of Mixed‐Halide Perovskite on Synthesis Step Using a Thermally Expandable Lamellar Capsule to Fabricate the Multi‐Conversion Layer

AbstractDespite the excellent performance of halide perovskite, low stability, and ion exchange between halides have remained obstacles to practical application. Herein, the polymer capsule encapsulated perovskite through the conventional hot‐injection method is reported to overcome the above issues. The residual heat generated during perovskite synthesis is utilized to expand the layer, and the perovskite particles are grown inside the polyethylene capsule. The products are gathered in a powder state, and the whole emission range can be synthesized. The water stability after 6 h soaked in water shows ≈90% and ≈75% for green and red, respectively. Also, due to the suppressed ion exchange, the single multi‐conversion layer for white light generation can be fabricated.

Urea-Assisted Sol-Gel Synthesis of LaMnO3 Perovskite with Accelerated Catalytic Activity for Application in Zn-Air Battery

Precious metal-based materials such as commercial Pt/C are available electrocatalysts for redox reactions in Zn-air batteries. However, their commercial use is still limited by slow kinetics and restricted stability. In this work, we highlight a facial urea-assisted sol-gel method to synthesize A-site vacancy in LaMnO3+δ oxide for boosting its catalytic activity and further explore the effect of the amount of urea on the A-site LaMnO3. The A-site vacancy in LMO was confirmed by XRD, TEM, and XPS, which revealed that the urea-assisted sol-gel method mitigated the A-site vacancy in LaMnO3+δ and increased its surface area, thus ultimately accelerating its redox reaction kinetics. The half-wave potential and current density of the resultant 3.0U-LMO electrocatalyst were 0.74 V and 5.74 mA cm−2, respectively. It is worth noting that the assembled Zn-air battery with the 3.0U-LMO catalyst presented a power output of 130.04 mW cm−2 at 0.51 V and a promising energy efficiency of 58.4% after 150 cycles. This protocol might offer an efficient approach for developing new defect-regulated perovskites for electrocatalysis.

Stable MAPbBr3@PbBr(OH) composites with high photoluminescence quantum yield: Synthesis, optical properties, formation mechanism, and catalytic application

The disappointing stability of perovskites against polar solvent and light irradiation severely hinders their application in photocatalysis. Here, we design a facile and reliable approach to synthesize MAPbBr3@PbBr(OH) composites with outstanding photoluminescence quantum yield (PLQY) of 74.4–90.6% and high stability under various harsh environments by simply introducing ZIF-67 or ZIF-8 in perovskite precursor solution. Benefiting from the preferential interaction between ZIF-67/ZIF-8 and MABr in the precursor step, the transformation of PbBr2 to PbBr(OH) triggered by ZIF-67/ZIF-8 occurs simultaneously with the formation of MAPbBr3 during the subsequent injection of toluene. PL intensity of the MAPbBr3@PbBr(OH) obtained by self-assembly of MAPbBr3 into PbBr(OH) can maintain above 95% of the initial after soaking in a wide variety of polar solvents for 210 days. Meanwhile, the composite also shows enhanced stability against continuous ultraviolet illumination. Moreover, the MAPbBr3@PbBr(OH) can be used in aqueous solution as photocatalyst for degradation of organic dye methylene green (MG) at room temperature. The MG degradation efficiency is observed to above 90% within 3 h. This work not only provides a reliable and controllable method for the synthesis of stable perovskites with high PLQY, but also pave the way for the use of perovskites as efficient photocatalyst in catalytic applications.

Barium and strontium doped La-based perovskite synthesis via sol-gel route and photocatalytic activity evaluation for methylene blue

In the current work, a La-based nanocomposite (LaxBa1−xSryCd1−yO3±δ) has been synthesized via sol-gel method. The influence of Ba and Sr doping on the structural, dielectric and photocatalytic characteristics of La-based perovskite nanocomposite has been investigated. The synthesized material was characterized employing different techniques such as FTIR, XRD, which confirmed the formation of nanocomposite. Representative peaks of metal oxygen bonds (M–O), in FTIR spectra confirmed the formation of the product. Orthorhombic crystalline structures having particle size 89.92 nm was confirmed by XRD analysis. Dielectric studies were conducted for the synthesized nanocomposite. The real and imaginary dielectric constant exhibited conservation and consumption of energy and AC conductivity analysis elaborated the effect of frequency on conductivity of the synthesized sample. Doping of nanomaterial with Ba and Sr caused inhomogeneity in the structure that caused reduction in number of moving charges due to which dielectric constant was found maximum at lower frequency. Enhanced dielectric properties caused a decrement in energy losses with increasing frequency. The results of AC conductivity were found directly related to frequency that may be due to enhanced charge storage capacity of perovskite after doping. In addition, synthesized nanoparticles exhibited excellent photocatalytic activity for the degradation of methylene blue (5 ppm). Under optimized conditions of pH, catalyst dose and UV light, 89.92% degradation of dye was achieved in 65 min. It is concluded that the synthesized nanomaterial i.e. Ba and Sr doped Lanthanum Perovskites can be a potent candidate for photocatalytic applications.

Template-free synthesis of perovskite (PEA)2PbI4 nanowires by ion-intercalation processing for single-nanowire photodetectors

Being different from the bulk semiconductors, one-dimensional (1D) semiconductor nanowires (NWs) have showed advantages such as high-density data storage, large-scale optoelectronic integration, and high-resolution optical imaging systems. Here, a template-free synthesis of perovskite (PEA)2PbI4 NWs by ion-intercalation processing and their applications for single-nanowire based photodetectors Ag/(PEA)2PbI4/Ag fabricated through interdigital electrodes, are presented. The dark current from the as-fabricated photodetectors Ag/(PEA)2PbI4/Ag is very low (∼ 4.792 ×10−11 A) due to the large electrode spacing, and a high responsivity of 2.098 A/W with a specific detectivity of 1.752 × 1012 Jones under 4.99 μW/cm2 520 nm illumination, and a high responsivity of 1.998 A/W with a specific detectivity of 1.669 × 1012 Jones under 5.01 μW/cm2 365 nm illumination, were obtained at − 5 V. Therefore, such a feasible synthesis method provides a promising way for low-cost, template-free, easy transferring for solution-synthesized perovskite NWs with high yield and repeatability, as well as for enhanced-performance individual NW optoelectronics.

Synthesis, characterization, and use of nanocast LaMnO3 perovskites in the catalytic production of imine by the gas-phase oxidative coupling of benzyl alcohol to aniline

We report here a green methodology for the synthesis of imine from a gas-phase oxidative coupling of benzyl alcohol to aniline in a continuous-flow system. These reactions were performed using LaMNO3 perovskites as heterogeneous catalysts. The catalytic performance of these materials was 98% and remained stable for 8 h of reaction. The prepared catalysts were successfully regenerated and reused in five successive catalytic cycles. No organic solvents were used in this process, which represents an important advantage in terms of the environment, simplicity, and safety. Moreover, this approach reduces the need for subsequent physicochemical extraction and purification steps.

How Methylammonium Iodide Reactant Size Affects Morphology and Defect Properties of Mechanochemically Synthesized MAPbI3 Powder

AbstractHere, we investigate in detail the impact of the size of the methylammonium iodide (MAI) reactants in the mechanochemical powder synthesis of the halide perovskite methylammonium lead iodide (MAPbI3). Morphology and structural characterizations by scanning electron microscopy and X‐ray diffraction reveal that with increasing MAI reactant size, the particle size of the perovskite powder increases, while its defect density decreases, as suggested by nuclear quadrupole resonance spectroscopy and photoluminescence investigations. The reason for this behavior seems to be associated to the sensitive influence of the MAI size on the time durations of MAPbI3 synthesis and delayed MAPbI3 crushing stage during ball milling. Thus, our results emphasize the high importance the reactant properties have on the mechanochemical synthesis of halide perovskites and will contribute to enhance the reproducibility and control of the fabrication of halide perovskites in powder form.

Synthesis of centimeter-size two-dimensional hybrid perovskite single crystals with tunable, pure, and stable luminescence.

The environment-friendly synthesis and property modulation of two-dimensional organic-inorganic halide perovskite (2D OHP) single crystals with large sizes and high quality are important for the fabrication of optoelectric devices. In this work, plate-like and centimeter-size (BA)2Pb(BrxI1-x)4 (BA = n-butylammonium, x: 0-1) single crystals with high crystallinity were synthesized via the cooling crystallization method in a mixed HX (X: I, Br) acid aqueous solution. The synthesized samples were single-phase with homogenously distributed Br and I ions. The lattice structure and bandgap of (BA)2Pb(BrxI1-x)4 were both finely tuned through halide alloying. Pure photoluminescence with unitary wavelength was obtained in the mixed-halide samples compared to those of monohalides (BA)2PbI4 and (BA)2PbBr4. This is attributed to the structural homogeneity of the alloyed crystals. Moreover, the prepared (BA)2Pb(BrxI1-x)4 samples showed higher photo and thermal stability for a long duration even with ion migration. This study will be an important reference for the fabrication and property modulation of 2D OHP-based light-emitting and other optoelectric devices.

Recent progress of copper halide perovskites: properties, synthesis and applications

Improvement in the synthesis of copper halide perovskites is fundamental in applications of different areas including LEDs, energy harvesting, detection,etc., and further highlights the direction for future research.

Research progress of synthesis of high-performance perovskites and its derivatives based on polyhedral distortion

Corner-shared coordination polyhedral crystals (CSCPCs) represented by perovskites have unique and various properties in optics, electrics, and magnetism, leading to their broad applications such as in serving as ferroelectric material, fast ionic conductors, and electro/photo-catalysts. However, the excellent properties are owned only by a very small fraction of CSCPS phases. How to obtain such phases through structural operation has always been a research hotspot and a bottleneck in related fields. Herein, we review the recent research progress of the synthesis of high-performance CSCPC materials from the perspective of phase structure, in order to clarify the intrinsic rules of phase evolution and reveal the mechanism behind the phase manipulation. We first systematically summarize the types of polyhedra and crystal frameworks in CSCPCs and classify the polyhedral distortions as three main types, i.e. cation displacements, polyhedral rotations, and deformations. Based on that, we further analyze and conclude different material synthesis methods. We find that most traditional synthesis methods rely on the phase transitions induced by the change of external physical conditions at a macroscopic level, such as composition, temperature, and pressure. Recently, there was an emerging synthesis method focusing on the microscopic manipulation of polyhedral geometry and topology, such as phase constructions according to tolerance-factor and substrate-proximity effects. The macroscopic synthesis methods and the microscopic synthesis methods share the same phase manipulation mechanism: making crystals transit into the structure-specified phases by inducing polyhedral distortions. The only difference is that the latter is more target-oriented, but its applications are currently limited to octahedral coordination tilt/rotation systems. Expanding its application scope is still a challenge. In addition, we propose two aspects that may be useful in optimizing the synthesis method: one is to clarify the origin of induced distortions and the interaction between different distortions, and the other is to customize the guidelines based on computer science. We hope that the research progress reviewed in this article can provide some valuable references and inspirations for designing and synthesizing the high-performance CSCPC materials.

Solvent-free synthetic protocols for halide perovskites

We discuss new opportunities in solvent-free synthesis of halide perovskites, including vapor deposition and mechanochemical methods.

Recent advances in synthesis of water-stable metal halide perovskites and photocatalytic applications

This review summarizes recent approaches for stabilizing metal halide perovskites in water, including surface engineering, common-ion effect, and intrinsic water stability as well as their photocatalytic applications.

Green and cost-effective morter grinding synthesis of bismuth-doped halide perovskites as efficient absorber materials

Due to the instability and toxicity issues of lead/tin-based halide perovskites, lead-free metal halide perovskites have emerged as an attractive lead replacement for several semiconductor applications. Here, we present a bismuth (Bi)-based perovskite structure as a low-toxic and potentially substitutable alternative to lead-based perovskite solar cells. The synthesis and optical performance of MAPbI3, MA3Bi2I9Clx, and (MAPbI3:BiCl3) with ratios (of 10, 30, 50, 70)% as lead-free and low lead perovskite are prepared. The grinding technique is used as a green chemistry method compared to a typical reaction for scaling up production. The phase identification, crystallinity, thermal stability, optoelectronic properties, and nanoscale composition are comprised. The results showed that the prepared samples are enhanced in the visible absorption region and aligned well with previous literature. Besides, the bandgap energy for the mixed-structured perovskite, at a molar ratio of 10%, was reduced to 1.52 eV compared to 1.55 and 1.80 eV for MAPbI3, MA3Bi2I9Clx, respectively. At room temperature, the samples emitted intense photoluminescence in the 680–700 nm region. Our findings demonstrate the processability of bismuth perovskites, aiding in the development of high-performance low toxic perovskites by assisting in the refinement of materials and processing methods.

ELECTRONIC STATES DENSITY, RESISTIVITY, AND PHASE COMPOSITION OF CaTiO3 PEROVSKITE WITH ISOMORPHIC IMPURITY OF NIOBIUM

The application of materials with a perovskite structure has currently become one of the most promising approaches for the development of photovoltaic systems. A method for high-speed synthesis (under 15 minutes) of CaTiO3 perovskite — TiO2 rutile with the possibility of concurrent doping of the product has been developed. The density of electronic states, phase composition features, and resistivity of niobium-doped perovskite (CaTiO3) were investigated. The calculations of the density of electronic states for niobium-doped CaTiO3 have shown that at low concentrations of niobium, the samples exhibit conductivity characteristic of semiconductors. Since niobium has one more valence electron compared to titanium, as the niobium content increases, the Fermi level shifts to the band of free states. This shift of the Fermi level should lead to a change in the nature of the conductivity of doped crystals, eventually transitioning to metallic conductivity at high concentrations of niobium. Composite analysis (СаТіО3+ТіО2) by X-ray diffraction has shown that the use of niobium as a doping element significantly accelerates the CaTiO3 synthesis reaction, and increases the perovskite concentration in the sample. The concentration of CaTiO3 in the sample the with niobium is 83 % vol. at a temperature of 900ºC and at a synthesis time of 5 min, whereas when using a mixture without Nb, the content of perovskite will be only 58 % vol. at a synthesis time of 12 min. X-ray phase analysis methods confirm the formation of a solid solution (doping) Ca(Ti,Nb)O3, resulting in the preparation of samples (СаТіО3+ТіО2) with resistivity inherent to semiconductors.

Synthesis and optical characterization of lead-free phenylenediammonium bismuth halide perovskites: a long charge carrier lifetime in phenylenediammonium bismuth iodide

Here we report the synthesis and properties of some lead-free organic bismuth halides. β-(PPD)2Bi2I10 has the longest average charge carrier lifetime (>1 μs) of the materials studied here, of the same order of magnitude as that of (CH3NH3)PbI3 and has a low band gap.

Blocking wide bandgap mixed halide perovskites’ decomposition through polymer inclusion

The relatively easy tunability of perovskites’ energy gap, as well as the synthesis of mixed halide perovskites, make them highly versatile and compatible with others semiconductor materials to produce efficient tandem solar cells.

Modification of TiO2 nanotubes by graphene–strontium and cobalt molybdate perovskite for efficient hydrogen evolution reaction in acidic medium

Herein, we demonstrate that modification of TiO2 nanotubes with graphene–strontium and cobalt molybdate perovskite can turn them into active electrocatalysts for hydrogen evolution reaction (HER). For this purpose, a simple method of hydrothermal synthesis of perovskites was developed directly on the TiO2 nanotubes substrate. Moreover, the obtained hybrids were also decorated with graphene oxide (GO) during one-step hydrothermal synthesis. The obtained materials were characterized by scanning electron microscopy with energy dispersive X-ray analysis, Raman spectroscopy, and X-ray diffraction analysis. Catalytic properties were verified by electrochemical methods (linear voltammetry, chronopotentiometry). The obtained hybrids were characterized by much better catalytic properties towards hydrogen evolution reaction compared to TiO2 and slightly worse than platinum. The optimized hybrid catalyst (decorated by GO) can drive a cathodic current density of 10 mA cm−2 at an overpotential of 121 mV for HER with a small Tafel slope of 90 mV dec−1 in 0.2 M H2SO4.

Au-Seeded CsPbI3 Nanowire Optoelectronics via Exothermic Nucleation.

Converting vapor precursors to solid nanostructures via a liquid noble-metal seed is a common vapor deposition principle. However, such a noble-metal-seeded process is excluded from the crystalline halide perovskite synthesis, mainly hindered by the growth mechanism shortness. Herein, powered by a spontaneous exothermic nucleation process (ΔH < 0), the Au-seeded CsPbI3 nanowires (NWs) growth is realized based on a vapor-liquid-solid (VLS) growth mode. It is energetically favored that the Au seeds are reacted with a Pb vapor precursor to form molten Au-Pb droplets at temperatures down to 212 °C, further triggering the low-temperature VLS growth of CsPbI3 NWs. More importantly, this Au-seeded process reduces in-bandgap trap states and consequently avoids Shockley-Read-Hall recombination, contributing to outstanding photodetector performances. Our work extends the powerful Au-seeded VLS growth mode to the emerging halide perovskites, which will facilitate their nanostructures with tailored material properties.

A Double Perovskite BaSrZrMnO6: Synthesis, Microstructural, Transport and Ferroelectric Properties

In this paper, the synthesis and characterization (structural, dielectric, electrical and optical) of a double perovskite, BaSrZrMnO6 (BSZMO), by a conventional solid-state reaction route are reported. The sample has an orthorhombic crystal symmetry with an average crystallite size of 40.7[Formula: see text]nm and a micro-lattice strain of 0.226%. A microstructural and compositional analysis was presented by using a scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDX), respectively. Grains are well-grown and distributed uniformly through well-defined grain boundaries on the sample surface to enhance physical properties. EDX analysis confirms the presence of all constituent elements and is well-supported by the Raman study. The analysis of the UV–Visible spectrum reveals an energy bandgap of 2.1[Formula: see text]eV, suitable for photovoltaic applications. The study of dielectric properties as a function of temperature and frequency reveals a Maxwell–Wagner type of dispersion and explores possible applications in energy storage devices. The discussion on the impedance spectroscopy supports the negative temperature coefficient of resistance (NTCR) character whereas the modulus study suggests a non-Debye type of relaxation in the sample. The study of AC conductivity confirms a thermally activated relaxation process. Both Nyquist and Cole–Cole plots support the semiconducting nature of the sample. The study of resistance versus temperature ([Formula: see text]) supports NTC thermistor character for temperature sensor applications. The analysis of the P-E loop reveals the possibility of the ferroelectrics’ character.

Synthesis and complex impedance analysis of nano cubic CH3NH3SnI3 perovskite for the development of optoelectronic lead-free Schottky diode

The synthesis of a lead-free tin-based perovskite material is a crucial step toward developing a sustainable energy device. However, the oxidation of Sn2+ to Sn4+ during synthesis in an open atmosphere is the basic synthetic problem in tin-based perovskites. In this study, a modified technique for nanoparticle synthesis was applied to submerge the oxidation issues and synthesised nano cubic tin-based hybrid CH3NH3SnI3 perovskite in the glove box in an inert environment (N2) to make the Schottky device. The crystallinity of the synthesised perovskite sample was confirmed by PXRD. The structural parameters such as crystalline size (D), dislocation density (δ), strain (ε), and the lattice parameter were calculated from the XRD pattern and were found to be 62.90 nm, 2.52 × 1014 nm−2, 6.12 × 10−3 lin−2/m−4, and 6.23951 Å, respectively. The material was characterised by UV–Vis. spectroscopy, TGA, FESEM, and EDX measurements. The frequency-dependent transport properties of this perovskite sample were investigated using complex impedance spectroscopy (CIS) in the frequency range of 4 Hz–8 MHz. The conductivity relaxation time, DC conductivity, and AC conductivity were calculated as 6.45 × 10−5 s, 2.01 × 10−6 S/m, and 6.98 × 10−4 S/m, respectively. A Schottky device was fabricated using this perovskite. Excellent performance of this device was observed from its electrical characterization in terms of conductivity both in the dark (1.04 × 10−6 S/m) and light (1.96 × 10−6 S/m) conditions. So, this work will be very beneficial to the further development of the lead-free CH3NH3SnI3 perovskite and its subsequent electrical applications.