Search Results (212)

The synthesis of ethylamine-based perovskites has emerged to attempt to replace the lead in lead-based perovskites for the alkaline earth elements barium and strontium, introducing chloride halide to prepare the perovskites in solar cell technology. X-ray diffraction studies were conducted, and EXPO2014 software was utilized to resolve the structure. Chemical characterization was performed using Fourier transform infrared spectroscopy, photophysical properties were analyzed through ultraviolet–visible spectroscopy, and photoluminescence properties were determined to confirm the perovskite characteristics. The software employed can determine new crystal structures, as follows: orthorhombic for barium perovskite CH₃CH₂NH₃BaCl₃ and tetragonal for strontium perovskite CH₃CH₂NH₃SrCl₃. The ultraviolet–visible spectroscopy data demonstrated that a temperature increase (90–110 °C) contributed to reducing the band gap from 3.93 eV to 3.67 eV for barium perovskite and from 4.05 eV to 3.84 eV for strontium perovskite. The results exhibited that new materials can be obtained through gentle chemistry and specialized software like EXPO2014, both of which are capable of conducting reciprocal and direct space analyses for identifying crystal structures using powder X-ray diffraction. Full article

Cs₂PtI₆ is a promising photoabsorber with a direct bandgap of 1.4 eV and a high carrier lifetime; however, the cost of Pt inhibits its commercial viability. Here, we performed a cost analysis and experimentally explored the effect of replacing Pt with earth-abundant Ni in solution-processed Cs(Pt_xNi_1−x)(I,Cl)₃ thin films on the properties and stability of the perovskite material. Films fabricated with CsI and PtI₂ precursors result in a perovskite phase with a bandgap of 2.13 eV which transitions into stable Cs₂PtI₆ with a bandgap of 1.6 eV upon annealing. The complete substitution of PtI₂ in films with CsI + NiCl₂ precursors results in a wider bandgap of 2.35 eV and SEM shows two phases—a rod-like structure identified as CsNi(I,Cl)₃ and residual white particles of CsI, also confirmed by XRD and Raman spectra. Upon extended thermal annealing, the bandgap reduces to 1.65 eV and transforms to CsNiCl₃ with a peak shift to higher 2-theta. The partial substitution of PtI₂ with NiCl₂ in mixed 50-50 Pt-Ni-based films produces a bandgap of 1.9 eV, exhibiting a phase of Cs(Pt,Ni)(I,Cl)₃ composition. A similar bandgap of 1.85 eV and the same diffraction pattern with improved crystallinity is observed after 100 h of annealing, confirming the formation of a stable mixed Pt-Ni phase. Full article

This study reviews the advanced anti-counterfeiting applications of CsCdCl₃, a lead-free all-inorganic perovskite crystal exhibiting dynamic luminescent properties responsive to temperature and UV light. Using synthesis methods such as Bridgman and hydrothermal techniques and incorporating dopants like bromine and tellurium, this research achieves improved luminescent stability, spectral diversity, and afterglow characteristics in CsCdCl₃. The crystal demonstrates extended afterglow, photochromic shifts, and temperature-sensitive luminescence, enabling applications in 4D encoding for secure data encryption and in cold-chain temperature monitoring for pharmaceuticals. Despite these promising attributes, the challenges related to photostability, batch consistency, and environmental resilience persist, necessitating further exploration into the optimized synthesis and doping strategies to enhance material stability. These findings underscore the potential of CsCdCl₃ for high-security information storage, pharmaceutical anti-counterfeiting, and real-time environmental sensing, positioning it as a valuable material for the next generation of secure, intelligent packaging solutions. Full article

Solar-driven hydrogen generation is one of the promising technologies developed to address the world’s growing energy demand in an sustainable way. While, for hydrogen generation (otherwise water splitting), photocatalytic, photoelectrochemical, and PV-integrated water splitting systems employing conventional semiconductor oxides materials and their electrodes have been under investigation for over a decade, lead (Pb)- halide perovskites (HPs) made their debut in 2016. Since then, the exceptional characteristics of these materials, such as their tunable optoelectronic properties, ease of processing, high absorption coefficients, and long diffusion lengths, have positioned them as a highly promising material for solar-driven water splitting. Like in solar photovoltaics, a solar-driven water splitting field is also dominated by Pb-HPs with ongoing efforts to improve material stability and hydrogen evolution/generation rate (HER). Despite this, with the unveiling potential of various Pb-free HP compositions in photovoltaics and optoelectronics researchers were inspired to explore the potential of these materials in water splitting. In this current review, we outlined the fundamentals of water splitting, provided a summary of Pb HPs in this field, and the associated issues are presented. Subsequently, Pb-free HP compositions and strategies employed for improving the photocatalytic and/or electrochemical activity of the material are discussed in detail. Finally, this review presents existing issues and the future potential of lead-free HPs, which show potential for enhancing productivity of solar-to-hydrogen conversion technologies. Full article

In this study, Ni/Ba co-doped NaNbO₃ ceramics (NBNNO_x) were synthesized using a solid-state method to explore the effects of Ni²⁺ and Ba²⁺ ion substitution on the structural, optical, and dielectric properties of NaNbO₃. X-ray diffraction (XRD) confirmed that the ceramics retained an orthorhombic structure, with crystallinity improving as the doping content (x) increased. Significant lattice distortions induced by the Ni/Ba co-doping were observed, which were essential for preserving the perovskite structure. Raman spectroscopy revealed local structural distortions, influencing optical properties and promoting relaxor behavior. Diffuse reflectance measurements revealed a significant decrease in band gap energy from 3.34 eV for undoped NaNbO₃ to 1.08 eV at x = 0.15, highlighting the impact of co-doping on band gap tunability. Dielectric measurements indicated relaxor-like behavior at room temperature for x = 0.15, characterized by frequency-dependent anomalies in permittivity and dielectric loss, likely due to ionic disorder and structural distortions. These findings demonstrate the potential of Ni/Ba co-doped NaNbO₃ ceramics for lead-free perovskite solar cells and other functional devices, where tunable optical and dielectric properties are highly desirable. Full article

In recent years, halide perovskite materials have become widely used in solar cells, photovoltaics, and LEDs, as well as photocatalysis. Lead-free perovskite Cs₃Bi₂I₉ has been demonstrated as an effective photocatalyst; however, the fast recombination of the photogenerated carriers hinders further improvements of its photocatalytic activity. In this work, Ti₃C₂ was composited with Cs₃Bi₂I₉ to promote the transfer and separation of photogenerated carriers, and thus the pollutant degradation efficiency was effectively improved. The visible-light photocatalytic reduction of Cs₃Bi₂I₉/Ti₃C₂ on rhodamine B (RhB), methylene blue (MB), and malachite green (MG) was as high as 97.3%, 96%, and 98.8%, respectively, improvements of almost 31.2%, 37.8%, and 37.2% compared to that of sole Cs₃Bi₂I₉. Our study provides a simple way to enhance the photocatalytic activity of lead-free halide perovskites. Full article

This paper investigates the optoelectronic properties of CsPbBr₃, a lead-based perovskite, and Cs₂AgBiBr₆, a lead-free double perovskite, in composite thick films synthesized using mechanochemical and hot press methods, with poly(butyl methacrylate) as the matrix. Comprehensive characterization was conducted, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–visible spectroscopy (UV–Vis), and photoluminescence (PL). Results indicate that the polymer matrix does not significantly impact the crystalline structure of the perovskites but has a direct impact on the grain size and surface area, enhancing the interfacial charge transfer of the composites. Optical characterization indicates minimal changes in bandgap energies across all different phases, with CsPbBr₃ exhibiting higher photocurrent than Cs₂AgBiBr₆. This is attributed to the CsPbBr₃ superior charge carrier mobility. Both composites showed photoconductive behavior, with Cs₂AgBiBr₆ also demonstrating higher-energy (X-ray) photon detection. These findings highlight the potential of both materials for advanced photodetector applications, with Cs₂AgBiBr₆ offering an environmentally Pb-free alternative. Full article

CsGeI₂Br-based perovskites, with their favorable band gap and high absorption coefficient, are promising candidates for the development of efficient lead-free perovskite solar cells (PSCs). However, bulk and interfacial carrier non-radiative recombination losses hinder the further improvement of power conversion efficiency and stability in PSCs. To overcome this challenge, the photovoltaic potential of the device is unlocked by optimizing the optical and electronic parameters through rigorous numerical simulation, which include tuning perovskite thickness, bulk defect density, and series and shunt resistance. Additionally, to make the simulation data as realistic as possible, recombination processes, such as Auger recombination, must be considered. In this simulation, when the Auger capture coefficient is increased to 10⁻²⁹ cm⁶ s⁻¹, the efficiency drops from 31.62% (without taking Auger recombination into account) to 29.10%. Since Auger recombination is unavoidable in experiments, carrier losses due to Auger recombination should be included in the analysis of the efficiency limit to avoid significantly overestimating the simulated device performance. Therefore, this paper provides valuable insights for designing realistic and efficient lead-free PSCs. Full article

Lead-based piezoelectric materials cause many environmental problems, regardless of their exceptional performance. To overcome this issue, a lead-free piezoelectric composite material was developed by incorporating different percentages of carbon fiber (CF) into the ceramic matrix of Bismuth Sodium Titanate (BNT) by employing the microwave sintering technique. The aim of this study was also to evaluate the impact of microwave sintering on the microstructure and the electrical behavior of the carbon-fiber-reinforced Bi_0.5Na_0.5TiO₃ composite (BNT-CF). A uniform distribution of the CF and increased densification of the BNT-CF was achieved, leading to improved piezoelectric properties. X-ray diffraction (XRD) showed the formation of a phase-pure crystalline perovskite structure consisting of CF and BNT. A Field Emission Scanning electron microscope (FESEM) revealed that utilizing microwave sintering at lower temperatures and shorter dwell times results in a superior densification of the BNT-CF. Raman Spectroscopy confirmed the perovskite structure of the BNT-CF and the presence of a Morphotropic Phase Boundary (MPB). An analysis of nanohardness indicated that the hardness of the BNT-CF increases with the increasing amount of CF. It is also revealed that the electrical conductivity of the BNT-CF at a low frequency is significantly influenced by the amount of CF and the temperature. Moreover, an increase in the carbon fiber concentration resulted in a decrease in dielectric properties. Finally, a lead-free piezoelectric BNT-CF showing dense and uniform microstructure was developed by the microwave sintering process. The promising properties of the BNT-CF make it attractive for many industrial applications. Full article

Sn-based halide perovskites are expected to be the best replacement for toxic lead-based counterparts, owing to their similar ionic radii and the optimal band gap for use in solar cells, as well as their versatile use in light-emitting diodes and photodetection applications. Concerns, however, exist about their stability under ambient conditions, an issue that is exacerbated in polycrystalline films because grain boundaries present large concentrations of defects and act as entrance points for oxygen and water, causing Sn oxidation. A current thriving research area in perovskite materials is the fabrication of perovskite single crystals, promising improved optoelectronic properties due to excellent uniformity, reduced defects, and the absence of grain boundaries. This review summarizes the most recent advances in the fabrication of single crystal Sn-based halide perovskites, with emphasis on synthesis methods, compositional engineering, and formation mechanisms, followed by a discussion of various challenges and appropriate strategies for improving their performance in optoelectronic applications. Full article

A bottleneck characterized by high strain and low hysteresis has constantly existed in the design process of piezoelectric actuators. In order to solve the problem that actuator materials cannot simultaneously exhibit large strain and low hysteresis under relatively high electric fields, Nb⁵⁺-doped 0.975(Ba_0.85Ca_0.15)[(Zr_0.1Ti_0.9)_0.999Nb_0.001]O₃-0.025(Bi_0.5Na_0.5)ZrO₃ (BCZTNb_0.001-0.025BiNZ) ceramic thick films were prepared by a film scraping process combined with a solid-state twin crystal method, and the influence of sintering temperature was studied systematically. All BCZTNb_0.001-0.025BiNZ ceramic thick films sintered at different sintering temperatures have a pure perovskite structure with multiphase coexistence, dense microstructure and typical dielectric relaxation behavior. The conduction mechanism of all samples at high temperatures is dominated by oxygen vacancies confirmed by linear fitting using the Arrhenius law. As the sintering temperature elevates, the grain size increases, inducing the improvement of dielectric, ferroelectric and field-induced strain performance. The 1325 °C sintered BCZTNb_0.001-0.025BiNZ ceramic thick film has the lowest hysteresis (1.34%) and relatively large unipolar strain (0.104%) at 60 kV/cm, showing relatively large strain and nearly zero strain hysteresis compared with most previously reported lead-free piezoelectric ceramics and presenting favorable application prospects in the actuator field. Full article

This article presents the research results of lead-free Ba_1−3/2xLa_x(Fe_0.5Nb_0.5)O₃ (BFNxLa) ceramic materials doped with La (x = 0.00–0.06) obtained via the solid-state reaction method. The tests of the BFNxLa ceramic samples included structural (X-ray), morphological (SEM, EDS, EPMA), DC electrical conductivity, and dielectric measurements. For all BFNxLa ceramic samples, the X-ray tests revealed a perovskite-type cubic structure with the space group Pm$\overline{3}$m. In the case of the samples with the highest amount of lanthanum, i.e., for x = 0.04 (BFN4La) and x = 0.06 (BFN6La), the X-ray analysis also showed a small amount of pyrochlore LaNbO₄ secondary phase. In the microstructure of BFNxLa ceramic samples, the average grain size decreases with increasing La content, affecting their dielectric properties. The BFN ceramics show relaxation properties, diffusion phase transition, and very high permittivity at room temperature (56,750 for 1 kHz). The admixture of lanthanum diminishes the permittivity values but effectively reduces the dielectric loss and electrical conductivity of the BFNxLa ceramic samples. All BFNxLa samples show a Debye-like relaxation behavior at lower frequencies; the frequency dispersion of the dielectric constant becomes weaker with increasing admixtures of lanthanum. Research has shown that using an appropriate amount of lanthanum introduced to BFN can obtain high permittivity values while decreasing dielectric loss and electrical conductivity, which predisposes them to energy storage applications. Full article

Lead toxicity has hindered the wide applications of lead halide perovskites in optoelectronics and bioimaging. A significant amount of effort has been made to synthesize lead-free halide perovskites as alternatives to lead halide perovskites. In this work, we demonstrate the feasibility of synthesizing CsSnI₃-based powders mechanochemically with dual light emissions under ambient conditions from CsI and SnI₂ powders. The formed CsSnI₃-based powders are divided into CsSnI₃-dominated powders and CsSnI₃-contained powders. Under the excitation of ultraviolet light of 365 nm in wavelength, the CsSnI₃-dominated powders emit green light with a wavelength centered at 540 nm, and the CsSnI₃-contained powders emit orange light with a wavelength centered at 608 nm. Both the CsSnI₃-dominated and CsSnI₃-contained powders exhibit infrared emission with the peak emission wavelengths centered at 916 nm and 925 nm, respectively, under a laser of 785 nm in wavelength. From the absorbance spectra, we obtain bandgaps of 2.32 eV and 2.08 eV for the CsSnI₃-dominated and CsSnI₃-contained powders, respectively. The CsSnI₃-contained powders exhibit the characteristics of thermal quenching and photoelectrical response under white light. Full article

In recent years, the photoelectric conversion efficiency of three–dimensional (3D) perovskites has seen significant improvements. However, the commercial application of 3D perovskites is hindered by stability issues and the toxicity of lead. Two–dimensional (2D) perovskites exhibit good stability but suffer from low efficiency. Designing efficient and stable lead–free 2D perovskite materials remains a crucial unsolved scientific challenge. This study, through structural prediction combined with first–principles calculations, successfully predicts a 2D perovskite, CsTeI₅. Theoretical calculations indicate that this compound possesses excellent stability and a theoretical efficiency of up to 29.3%, showing promise for successful application in thin–film solar cells. This research provides a new perspective for the design of efficient and stable lead-free 2D perovskites. Full article

To meet the current demand for lead-free piezoelectric ceramics, a novel sol-gel synthesis route is presented for the preparation of Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ doped with cerium (Ce = 0, 0.01, and 0.02 mol%) and vanadium (V = 0, 0.3, and 0.4 mol%). X-ray diffraction patterns reveal the formation of a perovskite phase (space group P4mm) for all samples after calcination at 800 °C and sintering at 1250, 1350, and 1450 °C, where it is proposed that both dopants occupy the B site. Sintering studies show that V doping allows the sintering temperature to be reduced to at least 1250 °C. Undoped BCZT samples sintered at the same temperature show reduced functional properties compared to V-doped samples, i.e., d₃₃ values increase by an order of magnitude with doping. The dissipation factor tan δ decreases with increasing sintering temperature for all doping concentrations, while the Curie temperature T_C increases for all V-doped samples, reaching 120 °C for high-concentration co-doped samples. All results indicate that vanadium doping can facilitate the processing of BCZT at lower sintering temperatures without compromising performance while promoting thermal property stability. Full article