Perovskite Structure Research Articles

Conductive single-phase SrMoO3 epitaxial films synthesized in pure Ar ambience via plasma-assisted radio frequency sputtering

ABSTRACT The cubic perovskite SrMoO3 with a paramagnetic ground state and remarkably low room-temperature resistivity has been considered as a suitable candidate for the new-era oxide-based technology. However, the difficulty of preparing single-phase SrMoO3 thin films by hydrogen-free sputtering has hindered their practical use, especially due to the formation of thermodynamically favorable SrMoO4 impurity. In this work, we developed a radio frequency sputtering technology enabling the reduction reaction and achieved conductive epitaxial SrMoO3 films with pure phase from a SrMoO4 target in a hydrogen-free, pure argon environment. We demonstrated the significance of controlling the target-to-substrate distance (TSD) on the synthesis of SrMoO3; the film resistivity drastically changes from 1.46 × 105 μΩ·cm to 250 μΩ·cm by adjusting the TSD. Cross-sectional microstructural analyses demonstrated that films with the lowest resistivity, deposited for TSD = 2.5 cm, possess a single-phase SrMoO3 with an epitaxial perovskite structure. The formation mechanism of the conductive single-phase SrMoO3 films can be attributed to the plasma-assisted growth process by tuning the TSD. Temperature-dependent resistivity and Hall effect studies revealed metal-like conducting properties for low-resistive SrMoO3 films, while the high-resistive ones displayed semiconductor-like behavior. Our approach makes hydrogen-free, reliable and cost-efficient scalable deposition of SrMoO3 films possible, which may open up promising prospects for a wide range of future applications of oxide materials.

Study the influence of Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite on optical, magnetic and antibacterial properties

Recently, we produced low cost SrFeO3-δ perovskite with antibacterial properties. In this study to improve the antibacterial properties of SrFeO3-δ perovskite, we doped it with silver. Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples were prepared by sol-gel method. Structural properties of these samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution TEM (HR-TEM), EDS elemental mapping and Fourier transform infrared spectrometer (FT-IR). These techniques confirmed the presence of small amount of cubic Ag spherical nanoparticles on the surface of the cubic Sr1-xAgxFeO3-δ perovskite structure. Further, X-ray photoelectron spectroscopy (XPS) for these samples revealed the presence of Ag1+ ions, oxygen vacancies and mixed valence states of Fe ions on the surface of the samples. The energy band gap of these samples was estimated using Kubelka–Munk equation and its value increased with increasing Ag up to x = 0.10. Additionally, Magnetic hysteresis (M − H) loops revealed that these samples displayed antiferromagnetic behavior with a small amount of ferromagnetic order. Finally, the antibacterial properties of these samples revealed that the antimicrobial activities were improved with increasing Ag (x = 0.10). Our results showed that Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples are a promising antimicrobial agent.Graphical

Mn-inlaid antiphase boundaries in perovskite structure

Improvements in the polarization of environmentally-friendly perovskite ferroelectrics have proved to be a challenging task in order to replace the toxic Pb-based counterparts. In contrast to common methods by complex chemical composition designs, we have formed Mn-inlaid antiphase boundaries in Mn-doped (K,Na)NbO3 thin films using pulsed laser deposition method. Here, we observed that mono- or bi-atomic layer of Mn has been identified to inlay along the antiphase boundaries to balance the charges originated from the deficiency of alkali ions and to induce the strain in the KNN films. Thus, rectangular saturated polarization-electric field hysteresis loops have been achieved, with a significantly improved twice remanent polarization of 114 μC/cm2 with an applied electric field of 606 kV/cm, which can be comparable to that of the typical Pb-based thin films. Moreover, we directly see the Mn occupation at the A-site of KNN perovskite structure using atomic-scale microstructure and composition analysis. The Mn-inlaid antiphase boundary can further enrich the understanding of perovskite crystal structure and give more possibilities for the design and optimization of perovskite materials.

Long-Term Comparisons of Photoluminescence Affected by Organic Cations of Formamidinium and Methylammonium in Monophasic Lead Iodide Perovskite Quantum Dots.

This study compared the photoluminescence (PL) stabilities of formamidinium (FA) and methylammonium (MA) in lead iodide perovskite quantum dots (QDs). To exclude other factors, such as size and purity, that may affect stability, MAPbI3 and FAPbI3 QDs with nearly identical sizes (~10.0 nm) were synthesized by controlling the ligand concentration and synthesis temperature. Transmission electron microscopy images and X-ray diffraction patterns confirmed homogeneous single-phase perovskite structures. Additionally, the bandgaps and sizes of the synthesized QDs closely matched those of the infinite quantum well model, which guaranteed that the photostability was solely caused by the different organic molecules in the two QDs. We analyzed the PL peak centers and full-width at half maximum of the QDs for 32 days. The enhanced stability of FAPbI3 was found to be caused by the nearly zero redshift (1.615 eV) of its PL peak, in contrast to the redshift (1.685→1.670 eV) of MAPbI3.

Tuning of structure, surface morphology and optical properties of spray-coated nickel tin oxide thin films by heat treatment

In this work, nickel tin oxide (NiSnO3) in a 1:1 ratio was synthesized using a simple spray pyrolysis technique followed by annealing at 450 °C for different time durations. The X-ray diffraction (XRD) revealed the polycrystalline nature with perovskite structure of NiSnO3 without the formation of any secondary phases. Annealing improved the crystallinity of the films. The annealed films exhibited a preference for orientation along the (310) plane. The largest crystallite size was obtained for 4 h of annealed film. The scanning electron microscopy (SEM) images of the films distinctly illustrate enhanced crystallinity following the annealing process. Energy-dispersive X-ray spectroscopy (EDS or EDX) indicates that the film possesses a near-stoichiometric composition. All the films resulted in more than 70 % transmittance in the visible region except for 8 h annealed. The gradual reduction of energy bandgap was observed for the sample. The four peaks at 358 nm, 415 nm, 436 nm, and 460 nm were observed in photoluminescence (PL) spectra corresponding to near band emission and defects related emissions respectively. The determined optical parameters from the present study indicate that the 4-h annealed film holds promise as a favourable option for optoelectronic and photonic devices.

Fabrication, structure, and physical properties of three-B-site perovskite Ba(Zr1–2xTixCex)O3

In this study, three-B-site perovskite Ba(Zr1–2xTixCex)O3 (x=0–0.2) materials with the co-substitution of Ti4+ and Ce4+ at the Zr-site of barium zirconate (BaZrO3) were successfully prepared. The analyses of XRD & Rietveld method, SEM, and TEM indicated that the substituted ions Ti4+ and Ce4+ entered the BaZrO3 lattice to form a single-phase solid solution, showing a conventional primitive cubic perovskite structure (Pm-3 m space group), and its lattice parameters gradually increased from 0.4192 nm to 0.4206 nm with x value. The sample with x=0.1 exhibited relatively optimal structural uniformity and densification, as well as comprehensive physical properties. The sample Ba(Zr0.8Ti0.1Ce0.1)O3 showed a minimum mean grain size of 1.50 μm. And due to the combined effect of solid solution formation and grain refinement, it displayed an apparent porosity of 1.42 % with a cold modulus of rupture (CMOR) of 123.8 MPa, and a thermal conductivity at ambient temperature of 2.197 W/mK. Furthermore, this three-B-site perovskite Ba(Zr1–2xTixCex)O3 exhibits excellent high-temperature stability. This study demonstrates the promising application of the dense, high-strength, and low-thermal conductivity Ba(Zr0.8Ti0.1Ce0.1)O3 perovskite material in the field of advanced refractory ceramics.

Insight view of thermal, mechanical and structural behavior of novel double perovskites Ba2XSbO6 (X = Sc, Y): A DFT based study

The study of double perovskite structures Ba2XSbO6 (X = Sc, Y) is carried out using the first principles algorithms within the framework of Density Functional Theory (DFT). The results showed that these compounds possess a cubic perovskite structure with the lattice space group Fm-3m generally represented by the group No. 225. The band structure of these compounds confirms their insulating nature. The calculated values of elastic parameters determined the brittle nature of Ba2ScSbO6 and Ba2YSbO6 compounds. Positive frequencies of the phonon dispersion curve indicates that these double perovskites are dynamically stable, with one acoustic and ten optical phonon modes having the combination of Raman active, Infrared active and optically inactive modes. The transport properties of these materials including electrical and thermal conductivity, as well as their thermoelectric power have been investigated. Additionally, the figure of merit was calculated to assess the suitability of double perovskites for thermoelectric devices and advanced technological applications.

Manganese doped La0.8Ba0.2FeO3 perovskite oxide as an efficient electrode material for supercapacitor

In this study, L0.8Ba0.2Fe1-xMnxO3 (LBFM-x, x = 0.0, 0.2, 0.5, 0.8) perovskite materials were synthesized by a Sol-Gel combustion method and were investigated as an electrode material for a supercapacitor device. The morphology, crystalline structure and electrochemical performance of the samples were studied in detail. The active points, where the electrochemical redox reaction takes place to store faradaic energy, are the oxygen vacancies on the surface of perovskite oxides. Partial substitution in the B-site of the perovskite structure, which is directly related to the oxygen vacancy in BO6 octahedral, is effective in optimizing the electrochemical performance. Based on the results of structural analysis, LBFM-0.2 has the highest concentration of oxygen vacancies; thus, it showed a higher electrochemical performance compared to other samples. The supercapacitors prepared with this electrode material should have an acceptably high specific capacitance of 685 F.g−1 at a current density of 2.0 A.g−1. The partial substitution of Mnn+ at the B-site increases the oxidation state of Fe cations and the mobility of oxygen ions through the oxygen vacancy sites. The electrochemical stability of LBFM-0.2, was evaluated by applying long charge-discharge cycles. After 3000 charge-discharge cycles, the supercapacitor was able to maintain about 94 % of its initial capacity.

Influence of calcination temperature on the 3D nanoscale topography of LaMnO3 thin films: A comprehensive surface analysis

In this paper, we present a comprehensive study on the 3D nanoscale topography of LaMnO3 thin films, focusing on the influence of calcination temperature on surface morphology. The study reveals significant structural, chemical, and morphological changes as a function of the calcination temperature. XRD analysis confirmed the formation of the orthorhombic LaMnO3 structure at 700 °C, 750 °C, and 800 °C, with increasing unit cell volume and crystallite size observed at higher temperatures. FTIR spectra identified characteristic functional groups associated with molecular vibrations, indicating the perovskite structure. SEM imaging showed grain growth with temperature, while EDS analysis confirmed compound formation and substrate interactions. AFM analysis revealed increased surface roughness with temperature, attributed to nucleation and crystal growth. Morphological and microtextural analyses further detailed changes in surface features, peaks, valleys, and voids. Fractal characterization highlighted variations in surface texture with temperature, with a decrease in dominant wavelength indicating changes in microtexture complexity. Overall, the findings provide insights into the temperature-dependent properties of LaMnO3 thin films, essential for optimizing growth conditions and understanding their potential applications in various fields.

Strain-incorporated structural, electronic, and dielectric properties of cubic FAPbCl3 perovskites together with the spin-orbit coupling

The organic-inorganic perovskite materials have garnered significant interest in solar technology because of their impressive structural, electrical, and optical characteristics. This study investigated the effects of hydrostatic strains (tensile and compressive) on the structural, electronic, and optical properties and the influence of spin-orbit coupling (SOC) on the electronic properties of formamidinium lead chloride cubic (FAPbCl3) perovskite structures employing first-principles density-functional theory (DFT). FAPbCl3 without SOC showed a semiconductor perovskite structure with a direct bandgap of 2.767 eV. Compressive strain (-8–0 %) reduced bandgaps, but tensile strain only increased them by +2 %. The SOC significantly reduced the bandgap by ∼1 eV, shifting it from direct to indirect. The analysis showed that neither of compressive or tensile strains can affect the system's semiconductiveness nature under the studied strain range. The dielectric function, loss spectrum, and absorption coefficient peaks of FAPbCl3 perovskites display a blueshift under compressive strains and a redshift under tensile strains. This material can be used in solar cells, lasers, and light detectors because of its promising electrical and optical properties.

LaMnO3-Type Perovskite Nanofibers as Effective Catalysts for On-Cell CH4 Reforming via Solid Oxide Fuel Cells.

CH4 has become the most attractive fuel for solid oxide fuel cells due to its wide availability, narrow explosion limit range, low price, and easy storage. Thus, we present the concept of on-cell reforming via SOFC power generation, in which CH4 and CO2 can be converted into H2 and the formed H2 is electrochemically oxidized on a Ni-BZCYYb anode. We modified the porosity and specific surface area of a perovskite reforming catalyst via an optimized electrostatic spinning method, and the prepared LCMN nanofibers, which displayed an ideal LaMnO3-type perovskite structure with a high specific surface area, were imposed on a conventional Ni-BZCYYb anode for on-cell CH4 reforming. Compared to LCMN nanoparticles used as on-cell reforming catalysts, the NF-SOFC showed lower ohmic and polarization resistances, indicating that the porous nanofibers could reduce the resistances of fuel gas transport and charge transport in the anode. Accordingly, the NF-SOFC displayed a maximum power density (MPD) of 781 mW cm-2 and a stable discharge voltage of around 0.62 V for 72 h without coking in the Ni-BZCYYb anode. The present LCMN NF materials and on-cell reforming system demonstrated stability and potential for highly efficient power generation with hydrocarbon fuels.

Tailoring magnetic properties of novel (La0.25Nd0.25Sm0.25Gd0.25)1-xHoxMnO3 high-entropy perovskite ceramics by Ho doping

High-entropy perovskite ceramics (HEPCs) with equal atomic ratios have recently emerged as a highly promising class of materials due to their unique magnetic properties. However, the crystal structure, microstructure and magnetic properties of unequal atomic ratios HEPCs have yet to be fully investigated. In this paper, single-phase HEPCs (La0.25Nd0.25Sm0.25Gd0.25)1-xHoxMnO3 ((LNSG)1-xHxMO) have been synthesized using solid-state reactions. The effect of Ho element content (x = 0.25, 0.3, 0.35 and 0.4) on the structure and magnetic properties was systematically investigated. All samples exhibit an orthorhombic perovskite structure with a Pbnm space group and show obvious crystallization characteristics after sintering at 1250 °C for 16 h (LNSG)1-xHxMO HEPCs display a smooth surface texture and distinct grain boundaries, as well as significant hysteresis effects at T = 5 K. The spin-orbit interaction and magnetic anisotropy between Ho and Mn ions increase with the increase of Ho content, which increases the saturation magnetization (Ms) of HEPCs. (LNSG)0.6H0.4MO exhibits the lowest magnetic hysteresis losses among the considered samples, attributed to its highest Ms (50.95 emu/g) and the lowest coercivity Hc (0.6 kOe). These characteristics endow it with a potential application in magnetic storage devices.

Application of the electrospinning technique in the preparation of selected electrode materials for solid oxide fuel cells

Abstract The electrospinning technique was applied to prepare cathode materials for solid oxide fuel cells (SOFCs). The research aimed to determine the influence of the Poly(vinylpyrrolidone) (PVP) content in the solution of a Sm0.5Ba0.25Sr0.25Co0.5Cu0.5O3-d perovskite oxide on the properties of the spun material, and consequently, on the performance of the fuel cell. The chosen material, commonly used as a cathode material for SOFCs, has been altered by the replacement of toxic barium and cobalt with less harmful strontium in the A-site and copper in the B-site. A single-phase perovskite structure was obtained after annealing at 900°C for two hours. The research included a process of preparing the precursor solution and obtaining samples by the electrospinning technique, followed by a series of studies to determine the morphology and phase composition, electrode and cell fabrication, and characterization of their electrochemical properties. The results indicated that material derived from a precursor with the addition of 15 wt.% PVP had the lowest polarization resistance values (e.g. 0,865 Ω cm−2 at 800 °C) between 600°C - 900°C temperature range. This material was then screen-printed on a commercial anode-supported fuel cell as a cathode layer, which allowed to achieve a promising power density value close to 300 mW cm−2 at 800 °C.

Investigating the potential of Nd and Co modified bismuth ferrite (BiFeO3) nanoparticles for advanced energy storage and electronic applications

In this study, we synthesized and characterized Nd and Co modified bismuth ferrite nanoparticles (BNFCO) using mechanical milling. X-ray diffraction (XRD) analysis has provided confirmation of the distorted rhombohedral, mixed rhombohedral-tetragonal and tetragonal perovskite structure with space group R3c and P2mm. Notably, these nanoparticles exhibited a high dielectric constant and low loss values at low frequencies and high temperatures, remaining around 103 up to 373 K before increasing to approximately 104, which opens new avenues for exploring temperature-sensitive dielectric properties. The AC conductivity adhered to Jonscher's power law, with dc conductivity values ranging from 10−5 to 10−3 s/cm, representing a significant advance in understanding electrical conduction in nanomaterials. Furthermore, we assessed the electrochemical behavior of the fabricated samples at varying concentrations using cyclic voltammetry, Galvanostatic charge and discharging (GCD), and electrochemical impedance spectroscopy (EIS) on a modified electrode. BNFCO (0.20) displayed exceptional properties with a capacitance of 510 F g−1 and a capacitance retention of 93.9 % after 5k cycles, making BNFCO nanomaterials potential candidates for supercapacitor applications. The multifunctional properties of Nd and Co modified bismuth ferrite nanoparticles presented in this study offer unparalleled opportunities for transformative applications in supercapacitors and optoelectronic devices.

Effect of the glycerol dispersant on the structure, electrical transport and magnetoresistive properties of La0.67Ca0.33MnO3 ceramics prepared by the sol-gel routine

In this paper, the sol-gel technique is employed to synthesize polycrystalline La0.67Ca0.33MnO3 (LCMO) ceramics, where methanol is chosen as the solvent. The crystal structure, morphology, as well as electrical and magnetoresistive properties were examined. Moreover, the effect of amount of the dispersant glycerol on the properties of LCMO ceramics is studied. X-ray diffraction (XRD) results showed that all samples crystallized in single phases with orthogonal perovskite structure (pnma space group), without any detectable impurity phases. Results reveal that the grain size of LCMO ceramics exhibits an initial increase followed by a decrease, accompanied by a similar behavior in the temperature coefficient of resistance (TCR) and magnetoresistance (MR). When the volume ratio of glycerol and methanol reached 2 %, the grain size is determined to be 7.30 μm, with TCR value of 25.02 % K−1 at T= 263.2 K, and MR value recorded at 55.40 %. The study elucidates the influence of glycerol on LCMO polycrystalline ceramics and optimize the fabrication process, thereby improve the electric transport property and magnetoresistance.

Enhancing the thermal stability of the dielectric property by tilting the NbO6 octahedra in (Na1-zKz)NbO3-SrTiO3 ceramics

(1-x) (Na0.2K0.8)NbO3-xSrTiO3 [(1-x) (N0.2K0.8)N-xST] ceramics with a homogeneous perovskite structure were well-sintered in the range of 1080–1160 °C. The 0.9(N0.2K0.8)N-0.1ST ceramic was found to have a temperature-stable dielectric constant (εr) that complies with the X9R multilayer ceramic capacitor (MLCC) requirement. The temperature stability of the εr value was also investigated for the 0.9(N1-zKz)N-0.1ST ceramics (0.0 ≤ z ≤ 1.0). The results indicated that as z (or K+ ions) increased, the Curie temperature (TC) decreased, and its peak broadened. The broadening of the TC peak was attributed to the development of the relaxor property owing to the tilting of the NbO6 octahedra. The 0.9(N1-zKz)N-0.1ST ceramics (0.7 ≤ z ≤ 1.0) exhibited a temperature-independent εr value, thus fulfilling the X9R MLCC requirement because of the broad TC peak. The MLCC fabricated from 0.9(N0.2K0.8)N-0.1ST thick films complied with the X9R MLCC requirement with excellent capacitance stability under the supplied electric field. Hence, 0.9(N1-zKz)N-0.1ST ceramics (0.7 ≤ z ≤ 1.0) are good candidates for X9R MLCCs.

Ferrimagnetic structures with rare-earth induced spin-reorientation in the Mn self-doped perovskite (Er0.7Mn0.3)MnO3

The search for spin-reorientation (SR) phase transitions, a spontaneous rotation of ordered magnetic moments, in ferrimagnetic (FiM) materials, which carry a net magnetization, is of fundamental and practical interest for applications in the field of spintronics. In this work, we have investigated Mn self-doped (Er0.7Mn0.3)MnO3 solid solution with GdFeO3-type Pnma perovskite structure by combining specific heat, magnetic susceptibility and neutron powder diffraction measurements. We provide experimental evidence for FiM order below TC = 104 K, and a spontaneous SR transition at TSR = 11 K. A FiM structure appears in all (R1-xMnx)MnO3 compounds with R = Dy–Lu for x ≥ 0.2. But in this structural family, R = Er is the only material with a SR transition. FiM order in (Er0.7Mn0.3)MnO3 appears with ferromagnetic (FM) ordering of Mn3+ and Mn4+ cations at the B site along the a-direction, which are antiferromagnetically (AFM) coupled with Er3+ and Mn2+ cations at the A site. At TSR, ordered Er3+ change direction from the magnetically harder a-axis to the magnetically easy b-axis and induce a change of the whole FiM structure, including the direction of all Mn spins from the irreducible representation mGM3+ to mGM4+. We calculated the crystal-field (CF) anisotropy for Ho3+ in (Ho0.8Mn0.2)MnO3 and Er3+ in (Er0.7Mn0.3)MnO3, based on the point charge model; the results revealed large magnetic anisotropies. For the FiM structure of (Ho0.8Mn0.2)MnO3, the magnetically easy a-axis of Ho3+ keeps the high-temperature magnetic directions along the a-axis and gives rise to a pronounced magnetization reversal effect at low temperature because of a significant rise of Ho3+ ordered moments. On the other hand, for the FiM structure of (Er0.7Mn0.3)MnO3, the magnetically easy b-axis of Er3+ gives rise to a SR phase transition at TSR, which does not lead to magnetization reversal even though Er3+ ordered moments rise significantly at low temperatures.

Enhancement of the environmental stability of perovskite thin films via AZ5214-photoresist and PMMA coatings

This study presents a novel investigation into enhancing the environmental stability of perovskite thin films, specifically focusing on the effects of AZ5214 photoresist compared to the widely studied PMMA. By employing advanced matrix encapsulation techniques, we aim to stabilize methylammonium lead iodide (MAPbI3) and methylammonium lead bromide (MAPbBr3) films, which are meticulously prepared via a two-step solution deposition method under controlled ambient conditions. Our approach involves spin-coating layers of poly(methyl methacrylate) (PMMA) and AZ5214 photoresist to singularly encapsulate the perovskite films. This encapsulation provides a robust hydrophobic barrier, significantly mitigating moisture ingress and addressing pinhole challenges within the perovskite structure. Through comprehensive characterizations—including scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy—we demonstrate that AZ5214 photoresist, despite being thicker than PMMA, offers significantly enhanced stability. Our study revealed that coating MAPbI3 perovskite with a 127-nanometer layer of PMMA resulted in a PL intensity retention of 44.8% after 40 days, which is a 589.23% improvement over the uncoated perovskite. Similarly, a 1200-nanometer layer of AZ5214 photoresist achieved a PL intensity retention of 38.2%, reflecting a 487.69% enhancement. For MAPbBr3 perovskite, the PMMA coating achieved a PL intensity retention of 43.1%, a 71.72% improvement, while the AZ5214 photoresist coating resulted in a retention of 48.4%, showing a 92.83% enhancement. These findings highlight the superior stability provided by AZ5214 photoresist, especially for MAPbBr3, making it a more effective barrier against environmental degradation compared to PMMA.

Stable and Highly Emissive Infrared Yb-Doped Perovskite Quantum Cutters Engineered by Machine Learning.

Quantum cutting (QC) allows the conversion of high-energy photons into lower-energy photons, exhibiting great potential for infrared communications. Yb-doped perovskite nanocrystals can achieve an efficient QC process with extremely high photoluminescence quantum yield (PLQY) thanks to the favorable Yb3+ incorporation in the perovskite structure. However, conventionally used oleic acid-oleylamine-based ligand pairs cause instability issues due to highly dynamic binding to surface states that have curbed their potential applications. Herein, zwitterionic type C3-sulfobetaine 3-(N,N-Dimethylpalmitylammonio)propanesulfonate molecule is utilized to build a strong binding state on the nanocrystals' surface through a new phosphine oxide synthesis route. Leveraging machine learning and Bayesian Optimization workflow to determine optimal synthesis conditions, near-infrared PLQY above 190% is achieved. The high PLQY is well maintained after over three months of aging, under high-flux continuous UV irradiation, and long continuous annealing. This is the first report of highly efficient and stable perovskite quantum cutters, which will drive the study of fundamental physics phenomena and near-infrared quantum communications.

Ambient Air Processed Inverted Inorganic Perovskite Solar Cells with over 21 % Efficiency Enabled by Multifunctional Ethacridine Lactate

AbstractAll‐inorganic cesium lead triiodide perovskites (CsPbI3) have attracted increasing attention due to their good thermal stability, remarkable optoelectronic properties, and adaptability in tandem solar cells. However, N2‐filled glovebox is generally required to strictly control the humidity during film fabrication due to the moisture‐induced black‐to‐yellow phase transition, which remains a great hinderance for further commercialization. Herein, we report an effective approach via incorporating multifunctional ethacridine lactate (EAL) to mitigate moisture invasion and enable the fabrication of efficient inverted (p‐i‐n) CsPbI3 perovskite solar cells (PSCs) under ambient condition. It is revealed that the lactate anions accelerate the crystallization of CsPbI3, shortening the exposure time to moisture during film fabrication. Meanwhile, the conjugated backbone and multiple functional groups in the ethacridine cations can interact with I− and Pb2+ to reduce the undesired defects, stabilize the perovskite structure and facilitate the charge transport in the film. Moreover, EAL incorporation also leads to better energy alignment, thus favoring charge extraction at both upper and bottom interfaces. Consequently, the device efficiency and stability are enormously enhanced, with the champion efficiency reaching 21.08 %. This even surpasses the highest value reported for the devices fabricated in glovebox, representing a record efficiency of inverted all‐inorganic PSCs.