Search Results (24)

The persistent operational instability of all-inorganic cesium lead halide (CsPbX₃) perovskite nanocrystals (NCs) has hindered their integration into white-light-emitting diodes (WLEDs). This study introduces a transformative approach by engineering a phase transition from CsPbBr₃ NCs to zirconium bromide (ZrBr₄)-stabilized hexagonal nanocomposites (HNs) through a modified hot-injection synthesis. Structural analyses revealed that the ZrBr₄-mediated phase transformation induced a structurally ordered lattice with minimized defects, significantly enhancing charge carrier confinement and radiative recombination efficiency. The resulting HNs achieved an exceptional photoluminescence quantum yield (PLQY) of 92%, prolonged emission lifetimes, and suppressed nonradiative decay, attributed to effective surface passivation. The WLEDs with HNs enabled a breakthrough luminous efficiency of 158 lm/W and a record color rendering index (CRI) of 98, outperforming conventional CsPbX₃-based devices. The WLEDs exhibited robust thermal stability, retaining over 80% of initial emission intensity at 100 °C, and demonstrated exceptional operational stability with negligible PL degradation during 50 h of continuous operation at 100 mA. Commission Internationale de l’Éclairage (CIE) coordinates of (0.35, 0.32) validated pure white-light emission with high chromatic fidelity. This work establishes ZrBr₄-mediated HNs as a paradigm-shifting material platform, addressing critical stability and efficiency challenges in perovskite optoelectronics and paving the way for next-generation, high-performance lighting solutions. Full article

Memristors are promising candidates for next-generation non-volatile memory devices, offering low power consumption and high-speed switching capabilities. However, conventional metal oxide-based memristors are constrained by fabrication complexity and high costs, limiting their commercial viability. Organic–inorganic hybrid perovskites (OIHPs), known for their facile solution processability and unique ionic–electronic conductivity, provide an attractive alternative. This study presents a conjugated polyelectrolyte (CPE), PhNa-1T, as an interlayer for OIHP memristors to enhance the high-resistance state (HRS) performance. A post-treatment process using n-octylammonium bromide (OABr) was further applied to optimize the interlayer properties. Devices treated with PhNa-1T/OABr achieved a significantly improved ON/OFF ratio of 2150, compared to 197 for untreated devices. Systematic characterization revealed that OABr treatment improved film morphology, reduced crystallite strain, and optimized energy level alignment, thereby reinforcing the Schottky barrier and minimizing current leakage. These findings highlight the potential of tailored interlayer engineering to improve OIHP-based memristor performance, offering promising prospects for applications in non-volatile memory technologies. Full article

Organic/inorganic hybrid perovskite materials, such as CH₃NH₃PbX₃ (X = I, Br), have attracted the attention of the scientific community due to their excellent properties such as a widely tunable bandgap, high optical absorption coefficient, excellent power conversion efficiency, etc. The exposure of perovskite solar cells and photovoltaic devices to heat can significantly degrade their performance. Therefore, elucidating their temperature-dependent optical properties is essential for performance optimization of perovskite solar cells. We synthesized CH₃NH₃PbBr₃ (MAPbBr₃) single crystals through the polymer-controlled nucleation route and investigated the optical properties and molecular structure evolution of them with temperature. Through temperature evolution photoluminescence (PL) spectroscopy, we found that the fluorescence intensity was greatly affected by increasing the temperature, with an asymmetric PL profile suggesting that more captured excitons undergo radiative complexation. The optical photographs showed that the color of MAPbBr₃ single crystals faded. Raman spectroscopy revealed that during the heating process, the structure of MAPbBr₃ was still preserved at 90 °C since all of the Raman bands were very clear. When the temperature increased to 120 °C, the Raman bands of the internal modes became very weak. On further heating, the inorganic framework on sample’s surface started to disintegrate above 210 °C. During the heating process, the PL spectra exhibited significant changes in spectral intensity, peak position and Full Width Half Maximum (FWHM). The PL spectral intensity decreased abruptly with increasing temperature. The peak position was blue shifted with increasing temperature, and the peak shape showed an obvious asymmetry. The FMWH of the PL spectra was gradually broadened with the increase in the temperature, and there was a sharp increase from 270 °C to 300 °C. These variations in the PL spectra with temperature indicate that the optical properties of MAPbBr₃ are greatly affected by temperature, which in turn affects the application of MAPbBr₃ in fields such as optical devices. These results may be instructive for the application of MAPbBr₃. Full article

As derivatives of metal halide perovskite materials, low-dimensional metal halide materials have become important materials that have attracted much attention in recent years. As one branch, zinc-based metal halides have the potential for practical applications due to their lead-free, low-toxicity and high-stability characteristics. However, pure zinc-based metal halide materials are still limited by their poor optical properties and cannot achieve large-scale practical applications. Therefore, in this work, we report an organic–inorganic hybrid zero-dimensional zinc bromide, (TDMP)ZnBr₄, using transition metal Mn²⁺ ions as dopants and incorporating them into the (TDMP)ZnBr₄ lattice. The original non-emissive (TDMP)ZnBr₄ exhibits bright green emission under the excitation of external UV light after the introduction of Mn²⁺ ions with a PL peak position located at 538 nm and a PLQY of up to 91.2%. Through the characterization of relevant photophysical properties and the results of theoretical calculations, we confirm that this green emission in Mn²⁺:(TDMP)ZnBr₄ originates from the ⁴T₁ → ⁶A₁ optical transition process of Mn²⁺ ions in the lattice structure, and the near-unity PLQY benefits from highly localized electrons generated by the unique zero-dimensional structure of the host material (TDMP)ZnBr₄. This work provides theoretical guidance and reference for expanding the family of zinc-based metal halide materials and improving and controlling their optical properties through ion doping. Full article

In the present work, a hybrid organic–inorganic semiconductor (HOIS) has been used to modify the surface of a graphite paste/silica (G–SiO₂) film electrode on a conducting glass substrate to fabricate a promising, sensitive voltammetric sensor for the vasoconstrictor bisartan BV6, which could possibly treat hypertension and COVID-19. The HOIS exhibits exceptional optoelectronic properties with promising applications not only in light-emitting diodes, lasers, or photovoltaics but also for the development of voltammetric sensors due to the ability of the immobilized HOIS lattice to interact with ions. This study involves the synthesis and characterization of an HOIS and its attachment on the surface of a G–SiO₂ film electrode in order to develop a nanocomposite, simple, sensitive with a fast-response, low-cost voltammetric sensor for BV6. The modified HOIS electrode was characterized using X-ray diffraction, scanning electron microscopy, and optical and photoluminescence spectroscopy, and its electrochemical behavior was examined using cyclic voltammetry. Under optimal conditions, the modified G–SiO₂ film electrode exhibited a higher electrocatalytic activity towards the oxidation of BV6 compared to a bare graphite paste electrode. The results showed that the peak current was proportional to BV6 concentration with a linear response range from 0 to 65 × 10⁻⁶ (coefficient of determination, 0.9767) and with a low detection limit of 1.5 × 10⁻⁶ M (S/N = 3), estimated based on the area under a voltammogram, while it was 3.5 × 10⁻⁶ for peak-based analysis. The sensor demonstrated good stability and reproducibility and was found to be appropriate for the determination of drug compounds such as BV6. Full article

Lead halide perovskites have been widely used in optoelectronic devices due to their excellent properties; however, the toxicity of lead and the poor stability of these perovskites hinder their further application. Herein, we report a zero-dimensional (0D) lead-free organic manganese (II) bromide hybrid compound of (TBA)₂MnBr₄ (TBA⁺ = tetrabutylammonium cation) single crystals (SCs) with great environmental stability. The (TBA)₂MnBr₄ SCs show a strong green emission peak at 518 nm with a high photoluminescence quantum yield (PLQY) of 84.98% at room temperature, which is attributed to the d-d transition of single Mn²⁺ ions, as also confirmed through density functional calculation. A green light-emitting diode was produced based on (TBA)₂MnBr₄ SCs, which exhibited CIE coordinates (0.17, 0.69) close to those of standard green. A photodetector fabricated by the (TBA)₂MnBr₄ SCs shows an obvious photo response with a rapid millisecond rise/decay response time (at 365 nm). Our findings promote the research of Mn(II)-based organic–inorganic hybrid materials and pave the way by using these materials for future high-performance optoelectronic devices. Full article

Organic-inorganic hybrid perovskite materials continue to attract significant interest due to their optoelectronic application. However, the degradation phenomenon associated with hybrid structures remains a challenging aspect of commercialization. To overcome the stability issue, we have assembled the methylammonium lead bromide nano islands (MNIs) on the backbone of poly-3-dodecyl-thiophene (PDT) for the first time. The structural and morphological properties of the MNI-PDT composite were confirmed with the aid of X-ray diffraction (XRD) studies, Field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS). The optical properties, namely absorption studies, were carried out by ultraviolet-visible spectroscopy. The fluorescent behavior is determined by photoluminescence (PL) spectroscopy. The emission peak for the MNI-PDT was observed at 536 nm. The morphology studies supported by FESEM indicated that the nano islands are completely covered on the surface of the polymer backbone, making the hybrid (MNI-PDT) stable under environmental conditions for three months. The interfacial interaction strategy developed in the present work will provide a new approach for the stabilization of hybrids for a longer time duration. Full article

The evolution of defects during perovskite film fabrication deteriorates the overall film quality and adversely affects the device efficiency of perovskite solar cells (PSCs). We endeavored to control the formation of defects by applying an additive engineering strategy using FABr, which retards the crystal growth formation of CsPbI_2.2Br_0.8 perovskite by developing an intermediate phase at the initial stage. Improved crystalline and pinhole-free perovskite film with an optimal concentration of FABr-0.8M% additive was realized through crystallographic and microscopic analysis. Suppressed non-radiative recombination was observed through photoluminescence with an improved lifetime of 125 ns for FABr-0.8M% compared to the control film (83 ns). The champion device efficiency of 17.95% was attained for the FABr-0.8M% PSC, while 15.94% efficiency was achieved in the control PSC under air atmospheric conditions. Furthermore, an impressively high indoor performance of 31.22% was achieved for the FABr-0.8M% PSC under 3200 K (1000 lux) LED as compared to the control (23.15%). With a realistic approach of air processing and controlling the crystallization kinetics in wide-bandgap halide PSCs, this investigation paves the way for implementing additive engineering strategies to reduce defects in halide perovskites, which can further benefit efficiency enhancements in outdoor and indoor applications. Full article

Owing to their composition-tunable and narrow emissions and high photoluminescence quantum yield (PLQY), inorganic halide perovskite quantum dots (IPQDs) are a promising option for wide color gamut displays. However, their practical applications have been limited by their lattice structure instability and surface defect states. Herein, CsPbBr₃:KBF₄@SiO₂ with improved stability and optical properties is successfully synthesized with a two-step optimization of fluorine (F) anion doping and SiO₂ in situ coating. Compared with bromide (Br), higher electronegativity and a smaller radius of F lead to stronger binding energy with Pb²⁺. Also, F anions can occupy surface Br vacancies. Then, benefiting from the acidic environment provided by BF₄⁻ hydrolysis, tetraethyl orthosilicate (TEOS) can be more easily hydrolyzed on the CsPbBr₃:KBF₄ surface to generate SiO₂ coating, thus further passivating lattice defects and improving environmental stability. Importantly, the PLQY of CsPbBr₃:KBF₄@SiO₂ achieves 85%, and the stability has been greatly improved compared with pure CsPbBr₃. Finally, CsPbBr₃:KBF₄@SiO₂/PDMS, CsPbI₃/PDMS, and CsPbCl₃/PDMS composites with narrow emissions are applied to replace traditional phosphors as color converters for direct-view light-emitting diode (LED) displays or liquid crystal display (LCD) backlights. The color gamut reaches 118.22% under the NTSC standard. Concerning the display field, it suggests likely applications in the future. Full article

Among all the inorganic perovskites, cesium lead bromide (CsPbBr${}_3$) has gained significant interest due to its stability and remarkable optoelectronic/photoluminescence properties. Because of the influence of deposition techniques, the experimental conditions that play a key role in each need to be addressed. In this context, we present CsPbBr${}_3$ films grown by pulsed laser deposition (PLD) and discuss the impact of oxygen stemming from their growth under a reduced vacuum, i.e., as the background atmosphere, rather than from post-growth exposure. In detail, stoichiometric mechano-chemically synthesized targets were prepared for deposition by nanosecond-PLD ($\lambda$ = 248 nm, $\tau$ = 20 ns, room temperature, fluence of 1 J/cm${}^2$) to produce slightly Br-deficient CsPbBr${}_3$ films under different background pressure conditions (P${}_0$ = 10${}^{-4}$, 10${}^{-2}$ Pa). The characterization results suggest that the presence of oxygen during the deposition of CsPbBr${}_3$ can advantageously passivate bromide-vacancy states in all the film thicknesses and reduce losses from emissions. Overall, our findings shed light on the critical role of oxygen, under conditions in which we ruled out other effects related to air exposure, and provide valuable guidelines for potential applications in various optoelectronic devices. Full article

In recent years, all-inorganic cesium lead bromide (CsPbBr₃) perovskites have garnered considerable attention for their prospective applications in green photonics and optoelectronic devices. However, the development of efficient and economical methods to obtain high-quality micron-sized single-crystalline CsPbBr₃ microplatelets (MPs) has become a challenge. Here, we report the synthesis of CsPbBr₃ MPs on Si/SiO₂ substrate by optimizing the ultrafast antisolvent method (FAS). This technique is able to produce well-dispersed, uniformly sized, and morphologically regular tetragonal phase single crystals, which can give strong green emission at room temperature, with excellent stability and excitonic character. Moreover, the crystals demonstrated lasing with a whispering gallery mode with a low threshold. These results suggest that the single-crystalline CsPbBr₃ MPs synthesized by this method are of high optical quality, holding vast potential for future applications in photonic devices. Full article

This paper demonstrates the generation of broadband emission in the visible and infrared ranges induced by a concentrated beam of infrared radiation from CsPbBr₃ ceramics doped with Yb³⁺ ions. The sample was obtained by the conventional solid-state reaction method, and XRD measurements confirmed the phase purity of the material crystallizing in the orthorhombic system. Spectroscopic measurements required further sample preparation in the form of ceramics using a high-pressure press. The research showed that as the excitation power increases, the emission intensity does not increase linearly from the beginning of the experiment. Irradiation of the material results in the accumulation of the delivered energy. Absorption of a sufficient number of photons triggers avalanche emission. It was found that the most intense luminescence is produced in a vacuum. Changes in conductivity were also observed, where the excitation was able to lower the resistivity of the material and it was highly dependent on the excitation power. The mechanism responsible for the generation of the observed phenomenon involving intervalence charge transfer (IVCT) transitions has been postulated. Full article

The field of hybrid organic–inorganic perovskite materials continues to attract the interest of the scientific community due to their fascinating properties and the plethora of promising applications in photovoltaic and optoelectronic devices. To enhance the efficiency and stability of perovskite-based devices, it is essential to discover novel compounds but also to investigate their various physicochemical, structural, and thermal properties. In this work, we report the synthesis and structural characterization of two novel hybrid lead bromide perovskites, combining the imidazolium cation (IMI) with methylammonium (MA) or formamidinium (FA) cations. The isolated polycrystalline powders were studied with X-ray powder diffraction (XPRD) and were formulated as (IMI)(MA)Pb₂Br₆, a 3D structure consisting of dimers of face-sharing octahedra linked in corner-sharing mode, and (IMI)(FA)PbBr₄, a 2D (110) oriented layer structure with zig-zag corner-sharing octahedra. The thermal stability of (IMI)(MA)Pb₂Br₆ and (IMI)(FA)PbBr₄ was investigated with thermogravimetric (TG) and differential scanning calorimetry (DSC) experiments which showed that both compounds are chemically stable (at least) up to 250 °C. Variable-temperature X-ray diffractometric (VT-XRD) studies of (IMI)(FA)PbBr₄ highlighted a structural modification occurring above 100 °C, that is a phase transformation from triclinic to orthorhombic, via an elusive monoclinic phase. Full article

Despite the fast-developing momentum of perovskite solar cells (PSCs) toward flexible roll-to-roll solar energy harvesting panels, their long-term stability remains to be the challenging obstacle in terms of moisture, light sensitivity, and thermal stress. Compositional engineering including less usage of volatile methylammonium bromide (MABr) and incorporating more formamidinium iodide (FAI) promises more phase stability. In this work, an embedded carbon cloth in carbon paste is utilized as the back contact in PSCs (having optimized perovskite composition), resulting in a high power conversion efficiency (PCE) of 15.4%, and the as-fabricated devices retain 60% of the initial PCE after more than 180 h (at the experiment temperature of 85 °C and under 40% relative humidity). These results are from devices without any encapsulation or light soaking pre-treatments, whereas Au-based PSCs retain 45% of the initial PCE at the same conditions with rapid degradation. In addition, the long-term device stability results reveal that poly[bis(4–phenyl) (2,4,6–trimethylphenyl) amine] (PTAA) is a more stable polymeric hole-transport material (HTM) at the 85 °C thermal stress than the copper thiocyanate (CuSCN) inorganic HTM for carbon-based devices. These results pave the way toward modifying additive-free and polymeric HTM for scalable carbon-based PSCs. Full article

Inorganic halide perovskites of the type AMX₃, where A is an inorganic cation, M is a metal cation, and X is a halide anion, have attracted attention for optoelectronics applications due to their better optical and electronic properties, and stability, under a moist and elevated temperature environment. In this contribution, the electronic, optical, thermoelectric, and elastic properties of cesium lead bromide, CsPbBr₃, and Rb-doped CsPbBr₃, were evaluated using the density functional theory (DFT). The generalized gradient approximation (GGA) in the scheme of Perdew, Burke, and Ernzerhof (PBE) was employed for the exchange–correlation potential. The calculated value of the lattice parameter is in agreement with the available experimental and theoretical results. According to the electronic property results, as the doping content increases, so does the energy bandgap, which decreases after doping 0.75. These compounds undergo a direct band gap and present an energies gap values of about 1.70 eV (x = 0), 3.76 eV (x = 0.75), and 1.71 eV (x = 1). The optical properties, such as the real and imaginary parts of the dielectric function, the absorption coefficient, optical conductivity, refractive index, and extinction coefficient, were studied. The thermoelectric results show that after raising the temperature to 800 K, the thermal and electrical conductivities of the compound RbxCs_1−xPbBr₃ increases (x = 0, 0.25, 0.50 and 1). Rb_0.75Cs_0.25PbBr₃ (x = 0.75), which has a large band gap, can work well for applications in the ultraviolet region of the spectrum, such as UV detectors, are potential candidates for solar cells; whereas, CsPbBr₃ (x = 0) and RbPbBr₃ (x = 1), have a narrow and direct band gap and outstanding absorption power in the visible ultraviolet energy range. Full article