Search Results (628)

In this work, we synthesized a lead-free halide double perovskite, Cs₂CuSbCl₆, with high carrier mobility via a one-pot hot-injection method. When combined with a high-resistivity silicon wafer, it forms a Type-II heterojunction structure, and its modulation depth reaches 84% by adjusting the annealing temperature. It demonstrates promising modulation performance at 532 nm. Owing to its strong absorption in the ultraviolet region, Cs₂CuSbCl₆ shows potential for application in ultraviolet-controlled terahertz modulation. Full article

Cesium lead chloride (CsPbCl₃) is a stable, wide-bandgap perovskite with significant potential for ultraviolet (UV) photodetection and blue light-emitting diodes (LEDs). However, the dynamical mechanisms of ferroelastic domain walls associated with the dielectric relaxations in a single-crystal have rarely been reported. In this work, we observed reversible phase transitions from cubic to tetragonal, and further to orthorhombic symmetry, accompanied by the formation and evolution of strip-like ferroelastic domain walls, using in situ X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and dielectric measurements. Notably, the dielectric studies revealed low temperature (~170–180 K) frequency-dependent loss peaks that we attribute to the pinning of polarized domain walls by chloride vacancies. We also found that the formation or disappearance of ferroelastic domain walls near the octahedral tilting transition temperatures leads to pronounced anomalies in the dielectric permittivity. These findings clarify the intrinsic phase behavior of CsPbCl₃ single crystals and underscore the significant contribution of ferroelastic domain walls to its dielectric response, providing insights for optimizing its optoelectronic performance. Full article

The poor stability of CsPbBr₃ perovskite nanocrystals (PNCs) caused by weak and dynamic ligand coordination severely limits their commercial applications. Herein, a dual-ligand synergistic modification strategy based on bromocarboxylic acids (BCAs) and oleylamine (OAm) was developed to mediate the surface structures and luminescent dynamics of CsPbBr₃ PNCs. The results reveal that carboxylate groups of BCA ligands modulate crystal growth, while its terminal Br atom forms a strong coordination with exposed Pb²⁺ on the PNCs surface, which can effectively passivate lead- and bromine-related defects. The synergistic protection of OAm ligands enhances the stability of PNCs via amino-halide electrostatic interactions and steric hindrance effects. Notably, based on the relatively dense surface coating of 4-bromobutyric acid (BBA) and OAm dual-ligands, the prepared CsPbBr₃ PNCs exhibit a high photoluminescence quantum yield (PLQY) of 85.2 ± 2.4% and remarkable storage stability, retaining 90.2 ± 1.7% of their initial PL intensity after being stored for 63 days under ambient conditions. Furthermore, a prototype white light-emitting diode (WLED) fabricated with these PNCs displays a wide color gamut covering 122.1% of the NTSC standard and a luminous efficacy of 64.6 lm/W. This work provides a facile and feasible ligand engineering strategy to obtain highly stable and emissive PNCs. Full article

Two-dimensional (2D) metal halide perovskites have attracted considerable interest for their markedly improved environmental stability and versatile compositional tunability compared to their three-dimensional (3D) counterparts. Nevertheless, the anisotropic charge transport caused by insulating organic spacers often leads to inefficient charge transport and limiting device performance. Precise control over crystallographic orientation, particularly achieving vertical alignment of the inorganic layers, is essential to facilitate out-of-plane charge transport and enhance device efficiency. This review systematically summarizes recent advances in understanding and controlling the crystallographic orientation of 2D perovskites, emphasizing manipulating strategies such as processing optimization, composition engineering, spacer design, solvent selection, and additive assistance to promote vertical alignment of inorganic layers and improve interlayer charge transport. We also discuss the influence of phase distribution, quantum well width, and crystal growth kinetics on device performance. Finally, we outline prevailing challenges and future opportunities for achieving the ideal microstructure and high-efficiency 2D perovskite solar cells. Full article

Metal halide perovskite (MHP)-based heterojunctions have become a forefront area in the research of optoelectronic functional materials due to their unique layered crystal structure, tunable band gaps, and exceptional optoelectronic properties. Recent studies have demonstrated that interface charge transfer is a crucial factor in determining the optoelectronic performance of the heterojunction devices. By constructing heterojunctions between MHPs and two-dimensional (2D) materials such as graphene, MoS₂, and WS₂, efficient electron–hole separation and transport can be achieved, significantly extending carrier lifetimes and suppressing non-radiative recombination. This results in enhanced response speed and energy conversion efficiency in photodetectors, photovoltaic devices, and light-emitting devices (LEDs). In these heterojunctions, the thickness of the MHP layer, interface defect density, and band alignment significantly influence carrier dynamics. Furthermore, techniques such as interface engineering, molecular passivation, and band engineering can effectively optimize charge separation efficiency and improve device stability. The integration of multilayer heterojunctions and flexible designs also presents new opportunities for expanding the functionality of high-performance optoelectronic devices. In this review, we systematically summarize the charge transfer mechanisms in MHP-based heterojunctions and highlight recent advances in their optoelectronic applications. Particular emphasis is placed on the influence of interfacial coupling on carrier generation, transport, and recombination dynamics. Furthermore, the ultrafast dynamic behaviors and band-engineering strategies in representative heterojunctions are elaborated, together with key factors and approaches for enhancing charge transfer efficiency. Finally, the potential of MHP heterojunctions for high-performance optoelectronic devices and emerging photonic systems is discussed. This review aims to provide a comprehensive theoretical and experimental reference for future research and to offer new insights into the rational design and application of flexible optoelectronics, photovoltaics, light-emitting devices, and quantum photonic technologies. Full article

Perovskite solar cells (PSCs) based on metal halides have garnered significant attention due to their exceptional power conversion efficiency (PCE) and compatibility with low-temperature fabrication processes. However, the development of stable and inexpensive carbon electrodes remains hindered by issues such as insufficient conductivity at the carbon electrode/perovskite interface and weak coupling strength. In this study, we employed a functionalized carbazole–cellulose composite (C–Cz) as an alternative binder to construct highly stable carbon electrodes for PSCs. The incorporation of C–Cz enhances electron interactions through its conjugated carbazole moieties, while the cellulose backbone facilitates uniform dispersion of carbon particles and forms continuous transport pathways. These synergistic effects significantly optimize interfacial energy alignment and defect passivation. Ultimately, p-i-n PSCs fabricated with C–Cz carbon paste electrodes achieved a champion PCE of 16.79%, substantially outperforming the control device using a conventional PMMA binder (10.56%). Notably, the exceptional hydrophobicity and defect passivation capabilities of the C–Cz electrode substantially enhance device durability—maintaining over 95% of initial efficiency after 400 h of continuous maximum power point tracking irradiation. This study reveals an effective adhesive engineering strategy for robust, scalable carbon electrodes, paving new pathways for practical applications in stable perovskite photovoltaics. Full article

Lead halide perovskites, exemplified by methylammonium (MA) lead iodide (MAPbI₃), combine strong optical absorption, long carrier diffusion lengths, and defect-tolerant electronic structure with facile processing, making them attractive for photovoltaics and radiation detection. Yet, their behavior under electron irradiation remains insufficiently understood, limiting deployment in space and dosimetry contexts. Here, we employ Monte Carlo simulations (Geant4) to model electron interactions with MAPbI₃ across energies from 0.1 to 100 MeV and absorber thicknesses from 10 μm to 1 cm. We quantify deposited energy, event statistics, energy per interaction, non-ionizing energy loss, and dominant radiation effects. The results reveal strong thickness-dependent regimes: thin photovoltaic-type layers (~hundreds of nanometers) are largely transparent to MeV electrons, minimizing bulk damage but allowing localized ionization, exciton self-trapping, and photoexcitation-driven ion migration. Although localized excitations can temporarily improve carrier collection under short-term exposure, their cumulative effect drives ionic rearrangement and defect growth, ultimately reducing device stability. In contrast, thicker detector-type films (10–100 μm) sustain multiple scattering and ionization cascades, enhancing sensitivity but accelerating defect accumulation. At centimeter scales, energy deposition saturates, enabling bulk-like absorption for high-flux dosimetry. Overall, electron irradiation in MAPbI₃ is dominated by electronic excitation rather than ballistic displacements, underscoring the need to optimize thickness and composition to balance efficiency, sensitivity, and durability. Full article

Doping lead-free halide perovskite nanocrystals with trivalent lanthanide ions has emerged as a promising strategy for engineering their optical properties in various photonic applications. Here, we report the design and synthesis of a series of lead-free double halide perovskite (Cs₂Na(In/Y/Gd)Cl₆) nanocrystals co-doped with a pair of different lanthanides (e.g., Tb³⁺, Dy³⁺, and Eu³⁺) as emission centers, and ns² ions (Sb³⁺ or Bi³⁺) as sensitizers. The tunability of the delayed photoluminescence spectral density was achieved through the selective excitation of lanthanide dopants either via ligand-to-metal charge transfer (e.g., Eu³⁺) or via ns² ion s-p transitions (e.g., Dy³⁺ or Tb³⁺). The intensities of the narrow lanthanide f-f emission bands can, therefore, be tuned by modulating the excitation wavelength and/or dopant ratio, allowing for the accurate engineering of the emission color coordinates and spectral density. We also demonstrated time-resolved tuning of the photoluminescence spectral density for the investigated nanocrystal host lattices co-doped with transition-metal (Mn²⁺) and lanthanide ions, owing to a large difference between the decay dynamics for Mn²⁺ d-d and lanthanide f-f transitions. The rational co-doping of double halide perovskite nanocrystals reported in this work provides a new strategy for generating pre-designed multilevel luminescent signatures for protection against counterfeiting. Full article

The chemical identity of oxygen species plays a decisive role in determining the optical stability of halide perovskite QD films. Here, real-time in situ spectroscopic monitoring, together with steady-state and time-resolved photoluminescence measurements, is utilized to differentiate the effects of molecular oxygen and plasma-activated oxygen species on CsPbBr₃ QD films. The films maintain nearly unchanged emission intensity, spectral profile, and carrier lifetimes when stored in vacuum or exposed to molecular O₂ even under UV illumination, demonstrating that neutral O₂ exhibits minimal reactivity toward the [PbBr₆]⁴⁻ framework. In contrast, oxygen plasma generates highly reactive atomic and ionic oxygen species that induce rapid and spatially heterogeneous photoluminescence quenching. This degradation is attributed to Br⁻ extraction, Br-vacancy formation, and subsequent Pb–O bond generation, which collectively introduce deep trap states and enhance nonradiative recombination. These findings clearly indicate that reactive oxygen species rather than molecular O₂ are the dominant driver of oxygen-induced luminescence degradation, providing mechanistic insight and offering processing guidelines for the reliable integration of perovskite nanomaterials in optoelectronic devices. Full article

Lead halide-based perovskite solar cells have gained significant attention from academia and the photovoltaic industry due to their exceptional optical and electrical characteristics. The primary problem with Pb-based perovskite pertains to its toxicity and solubility in water within the external environment. These concerns regarding hazards to the environment are constraining the application of lead-based perovskite in both consumer and industrial contexts. To offer a viable alternative to lead-based hazardous perovskite solar cells, we examined an inverted (p-i-n) perovskite structure with three distinct absorber layers based on cesium bismuth halides (Cs₃Bi₂I₉, Cs₃Bi₂Cl₉, Cs₃Bi₂Br₉) and conducted a comparative analysis utilizing SCAPS-1D software (version 3.3.08). The comparison analysis of our design against starting parameters indicated that the optimal power conversion efficiency (PCE) of 10.01% was recorded for Cs₃Bi₂I₉, 7.56% for Cs₃Bi₂Br₉, and 4.34% for Cs₃Bi₂Cl₉. Following careful optimization of the thickness of charge-transport layers (CTLs), doping concentrations of CTLs, and all three absorber layers, the overall efficiencies of the three inverted structures were enhanced from 10.01% to 14.08% for Cs₃Bi₂I₉, from 4.34% to 5.28% for Cs3Bi2Cl9, and from 7.56% to 11.05% for Cs₃Bi₂Br₉, respectively. The other performance enhancement, open-circuit voltage, increased from 1.08 V to 1.37 V for Cs₃Bi₂I₉, from 1.26 V to 1.47 V for Cs₃Bi₂Cl₉, and from 1.20 V to 1.47 V for Cs₃Bi₂Br₉. This comparative analysis of proposed perovskite devices demonstrates that Cs₃Bi₂X-based perovskite devices possess significant potential to replace conventional hazardous solar cells in the renewable and clean energy sectors. Full article

Lead-free chalcogenide perovskites are emerging as promising alternatives to hybrid halide perovskites due to their superior thermal stability, non-toxicity, and strong optical absorption. In this study, the photovoltaic performance of single-junction BaHfSe₃-based perovskite solar cells (PSCs) with the TCO/TiO₂/BaHfSe₃/Cu₂O/Au configuration is systematically investigated using SCAPS-1D simulations. Device optimization identifies TiO₂ and Cu₂O as suitable ETL and HTL materials, respectively. The optimized structure—TCO/TiO₂ (50 nm)/BaHfSe₃ (500 nm)/Cu₂O (100 nm)/Au—achieves a power conversion efficiency (PCE) of 24.47% under standard conditions. Simulation results reveal that device efficiency is influenced by absorber thickness and trap density. A detailed temperature-dependent study highlights that photovoltaic parameter efficiency is governed by the barrier alignment at the TCO/ETL interface. For lower TCO (Transparent Conducting Oxide) work functions (3.97–4.07 eV), PCE decreases monotonically with temperature, attributed to the increase in reverse saturation current resulting from a higher intrinsic carrier concentration. By contrast, higher TCO work functions (4.47–4.8 eV) yield an initial increase in efficiency with temperature, driven by reduced barrier height and favorable Fermi level shifts before efficiency declines at further elevated temperatures. These insights underscore the promise of BaHfSe₃ as a lead-free, environmentally robust perovskite absorber for next-generation PSCs, and highlight the critical importance of interface engineering for achieving optimal thermal and operational performance. Full article

Rapid progress on the fabrication of lead halide perovskite has led to the development of high performance optoelectronic devices, particularly in the field of solar cell technologies. This initial success has subsequently inspired investigations into layered 2D-halide perovskite structures, motivated in part by their good environmental stability, but more significantly by their intriguing fundamental photo-physics. They have recently been used to improve the photoresponsivity of monolayer transition metal dichalcogenides in hybrid heterostructures. In this paper, we report on the synthesis of the (PEA)₂(MA)_n−1Pb_nI_3n+1 series (with n = 1, 2, 3) of 2D-halide perovskites, in order to develop a platform that provides ultra-thin layers for the fabrication of hybrid heterostructures. The crystal synthesis method and its basic structural and optical characterization are shown, highlighting the differences in the crystal synthesis processes. Furthermore, we explore the preparation of 2D halide perovskite ultra-thin flakes using the mechanical exfoliation method, and few-layer-areas of n = 1 member of the series are identified using atomic force microscopy. Finally, we study the deposition of thin and ultra-thin films using the spin coating technique to provide an alternative process to the exfoliation. Full article

Zero-dimensional (0D) tin halide perovskites have emerged as promising luminescent materials owing to their broadband emission, high quantum yield, and negligible self-absorption. Yet, their luminescence efficiency and stability remain insufficient for practical optoelectronic applications. Here, Sb³⁺ dopants are introduced into Cs₄SnBr₆ through a water-assisted wet ball milling strategy, resulting in bright and thermally robust emission. The doped materials exhibit pronounced self-trapped exciton (STE) luminescence centered at 525 nm with a broad full width at half maximum of 110 nm, a large Stokes shift of approximately ~1.3 eV, and a photoluminescence lifetime of ~0.8 µs. Remarkably, Sb³⁺ incorporation boosts the photoluminescence quantum yield (PLQY) up to 64% at room temperature while simultaneously improving thermal stability. Correlated spectroscopic analyses reveal that the Sb³⁺-induced lattice distortion of the [SnBr₆]⁴⁻ octahedra strengthens electron–phonon interactions and elevates the STE binding energy, thereby stabilizing the excited states and suppressing nonradiative losses. Full article

Methylammonium lead iodide (MAPbI₃) perovskite has been widely studied for its optoelectronic properties, but its polycrystalline thin films inevitably contain grain boundaries and defects that degrade performance and stability. PbI₂ is often considered a destabilizing agent in perovskites, yet it has also been reported to act as a passivation agent, making its role a subject of debate. Here, we performed integrated optical, photoluminescence (PL), and ultra-low-frequency Raman mapping on a 100 μm² region of MAPbI₃ thin films to study the roles of PbI₂. The analyses resolved α-phase MAPbI₃-rich, PbI₂-rich, and mixed-phase domains, revealing heterogeneous PbI₂ distribution with PL quenching at defect sites. In addition, after light-induced degradation, PL changes were governed by both the local microstructure and PbI₂ distribution. Notably, PbI₂-rich regions retained PL, evidencing a protective passivation effect. These findings demonstrate that the beneficial role of PbI₂ is key to designing more stable perovskite devices. Full article

During the growth of lead halide perovskite single crystals (SCs) with the conventional inverse temperature crystallization (ITC) method, the blast nucleation of the precursor under supersaturation conditions is always unavoidable. In the current study, three kinds of additives namely methanol (MOE), ethyl alcohol (EtOH), and polyethylene glycol (PEG) are introduced to regulate the growth of CsPbBr₃ SCs. Benefiting from the strong anchoring hydroxy groups (-OH) with the Pb²⁺ species, large-sized CsPbBr₃ crystals with reduced defect densities were prepared (PEG-regulated). In addition, the viscosity of the precursor solution increases after adding PEG additive, which provides a more stabilized environment for crystal growth. Finally, the photodetectors prepared from our PEG-tuned CsPbBr₃ SCs show a responsivity of 2.25 A/W and a detectivity of 6.06 × 10¹¹ Jones, demonstrating the potential of CsPbBr₃ SCs for photo-detecting applications. Full article