Search Results (1,073)

Perovskite light-emitting diodes (PeLEDs) have attracted considerable attention due to their outstanding electroluminescent properties and have achieved remarkable progress. However, charge injection imbalance remains a major obstacle limiting the performance of near-infrared (NIR) PeLEDs. Herein, we propose inserting a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) buffer layer between ITO and Zinc oxide (ZnO) to reduce electron injection. This layer also acts as a substrate to modulate ZnO surface roughness, thereby improving perovskite film quality. Through this optimization, the device’s external quantum efficiency (EQE) increases from 20% to 22%, and its T₅₀ operational lifetime extends from 3.4 h to 17.8 h. Importantly, we successfully integrate the PEDOT:PSS buffer layer into scalable fabrication, demonstrating NIR-PeLEDs with a uniform emission area of 2500 mm². Full article

Integration of lead zirconate titanate (PZT) films on metallic substrates is important for flexible piezoelectric devices, but achieving highly textured crystallinity without detrimental interfacial diffusion or oxidation remains challenging. In this work, PZT thick films (~1.3 μm) were deposited on titanium substrates using radio-frequency magnetron sputtering at 400 °C followed by rapid thermal processing at 640 °C for 2.5 min. A conductive LaNiO₃ buffer layer was introduced to promote the nucleation of the perovskite phase and suppress interfacial degradation. The resulting PZT films on the LNO/Pt/Ti substrates exhibit a strong (001) preferred orientation and a dense microstructure. The films show a large remnant polarization P_r of ~61 μC cm⁻² and a low coercive field E_c of ~56 kV cm⁻¹ at 60 V, together with a dielectric constant ε_r of ~1350–1612 and a dielectric loss tanδ ≤ 0.06 in the frequency range of 1 kHz to 1 MHz. Patterned Pt/PZT/LNO/Pt/Ti cantilevers yield a transverse piezoelectric coefficient e_31,f of ~−6.7 C/m², significantly outperforming reported piezoelectric films deposited on Ti. These results demonstrate that controlled nucleation and rapid thermal crystallization enable highly textured PZT films on reactive metallic substrates, providing a viable route for flexible piezoelectric MEMS devices. Full article

Two-dimensional organic–inorganic hybrid perovskite (2D-OIHP) heterostructures provide a versatile platform for crystal engineering because their composition, dimensionality, excitonic structure and interfacial energy alignment can be tuned at the molecular level. However, the same ionic softness that enables facile chemical transformation also leads to ion migration under thermal, electrical and optical stimuli. In 2D-OIHP heterostructures, ion migration is not only a degradation pathway; it determines whether a heterointerface remains sharp, becomes compositionally graded, evolves into a mixed-halide alloy, or forms a bias-programmed functional junction. This review summarizes recent progress in understanding ion migration in 2D-OIHP-based heterostructures, with emphasis on migration species, driving forces, pathways and interface evolution. We first classify representative fabrication strategies according to the initial interface profiles they generate. We then discuss thermally driven in-plane and out-of-plane halide migration, spacer-cation engineering for suppressing interdiffusion, and electric-field-induced directional migration in functional devices. Finally, we extract design rules and unresolved challenges for achieving stable, sharp or dynamically programmable perovskite heterostructures. The aim is to provide a mechanistic framework for using ion migration as both a stability criterion and a crystal-engineering tool in layered hybrid perovskites. Full article

Maximising the energy yield of perovskite solar cells (PSCs) through bifacial architectures is a promising route toward commercialisation. However, optimising charge extraction at the interfaces remains a critical challenge. In this study, we systematically compare tin dioxide (SnO₂) and titanium dioxide (TiO₂) electron transport layers (ETLs) in bifacial guanidinium-incorporated PSCs with a transparent gold (10 nm) back electrode. While the bulk perovskite crystallinity remains invariant on both substrates, SnO₂ provides a distinct optical advantage through enhanced UV-blue transmittance. Beyond these optical benefits, comprehensive recombination process analyses reveal that SnO₂ drastically suppresses non-radiative recombination. The SnO₂ layer effectively mitigates defect states, significantly reducing both bulk and surface trap-assisted recombination rates without disrupting intrinsic bimolecular charge transport. Ultimately, these findings underscore the critical importance of rational interfacial engineering to neutralise defects, proving SnO₂ to be an indispensable component for realising highly efficient and commercially viable bifacial perovskite optoelectronics. Full article

As global energy demand continues to rise and the need for environmental conservation grows more urgent, solar energy has attracted substantial attention owing to its inherent cleanliness and sustainability. Perovskite solar cells (PSCs), an innovative photovoltaic technology, have shown significant improvements in photoelectric conversion efficiency (PCE) since their introduction. Nevertheless, significant challenges remain in enhancing efficiency and ensuring long-term stability. Naturally abundant and environmentally benign carbon materials represent a promising alternative. Incorporating carbon materials into PSCs can yield beneficial effects, such as controlling the crystallization rate of the perovskite layer, improving carrier transport properties, and realizing interface modification between various functional layers. This review systematically reviews the application of carbon materials in PSCs, including carbon nanotubes (CNT s), carbon dots (CDs), carbon nanofibers (CNFs), fullerenes, and their derivatives, thereby contributing to sustainable development by enhancing resource efficiency, device stability, and environmental compatibility of PSCs. Full article

Thermal barrier coatings (TBCs) require materials with intrinsically low thermal conductivity and high grain-boundary thermal resistance to maximize the temperature gradient across the top coat. In this work, the effective thermal conductivity of more than 40 prospective TBC oxides belonging to seven structural families (YSZ/YSH, pyrochlores/fluorites A₂B₂O₇, defective fluorites A₃BO₇, fergusonite/monazite ABO₄, and perovskites ABO₃) was systematically deconvoluted into intrinsic grain thermal conductivity (k_grain) and grain-boundary (R_gb) contributions. It is shown that grain-boundary Kapitza resistance dominates heat transport in virtually all advanced oxides, contributing 60–90% to the total thermal resistance of polycrystalline samples. The lowest k_grain values (4–12 W m⁻¹ K⁻¹) are found for cerates and certain tantalates, while the highest R_gb (up to 7.2 × 10⁻⁶ m² K W⁻¹) are characteristic of high-entropy and heavily doped perovskites. Orthorhombically distorted SrCeO₃-based and high-entropy perovskites combine moderate k_grain (4.7–27.9 W m⁻¹ K⁻¹), high R_gb, and tunable thermal-expansion coefficients (10–13 × 10⁻⁶ K⁻¹), making them the most promising candidates for next-generation TBCs. These findings provide a rational basis for microstructure engineering and composition design aimed at maximizing the temperature drop across TBC layers while maintaining phase stability and CMAS resistance. Full article

Lead-free perovskite solar cells have become promising materials in the solar energy field; however, there are some constraints limiting their efficiency, like unfavorable band alignment, high defect densities, and inefficient charge extraction. Cs₃Sb₂I₉ is a lead-free material that has excellent stability, but its experimentally reported efficiencies remain low (<4%). Therefore, Cs₃Sb₂I₉ device performance was investigated using the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D), where the planar n–i–p structure was analyzed, focusing on its band alignment, transport layers, and key device parameters. The optimized device achieved a power conversion efficiency (PCE) of 13.62%, an open circuit voltage (Voc) of 1.37 V, a short circuit current density (Jsc) of 11.77 mA/cm², and a fill factor (FF) of 84.15% with a 180 nm PCBM electron transport layer, a 150 nm Cu₂O hole transport layer, and a 500 nm absorber thickness. This study advances the development of efficient lead-free perovskite solar cells, promoting sustainable and clean energy. Full article

CH₃NH₃PbBr₃ (MAPbBr₃) single crystals have shown great potential in X/γ-ray detection. However, stable electrodes for MAPbBr₃ single crystals still remain challenging. In this work, multi-layer electrodes including Au, Au/Ti and Au/Pt/Ti are investigated. Through I-V characterization, Au/Pt/Ti shows Ohmic contact behavior and the lowest dark current. The potential contact is also confirmed by the Kelvin force probe. Based on these low-noise electrodes, 59.5 keV monochromatic X-ray photon-counting detection and imaging is demonstrated. This work provides useful information for electrode design in lead halide perovskite-based optoelectronic devices. Full article

Narrow-bandgap tin–lead (Sn–Pb) perovskite solar cells (PSCs) are essential for high-performance tandem photovoltaics, yet their operational stability and efficiency suffer from spontaneous Sn²⁺ oxidation, interfacial defects, and non-radiative recombination. Current passivation strategies often provide only a single modification mode and struggle to adequately stabilize Sn²⁺ without introducing charge-transport barriers. Here, we introduce morpholine acetate (MPAC) as a novel interfacial passivator to achieve synergistic chemical and field-effect passivation in Sn–Pb perovskites. The acetate group of MPAC coordinates with undercoordinated metal cations, suppressing Sn²⁺ oxidation and minimizing defect states. Simultaneously, the morpholine moiety forms an interfacial dipole layer that aligns energy levels to facilitate charge extraction. Consequently, MPAC-modified PSCs achieve a champion power conversion efficiency of 22.64%. Under continuous AM 1.5G illumination without optical filters (xenon lamp, 65 °C, open-circuit conditions), the unencapsulated devices maintain over 90% of their initial efficiency after 192 h, providing a promising route to balance performance and durability. Full article

Perovskite solar cells in aerospace applications are promising due to their high power output, radiation tolerance, and ability to extend spacecraft operational lifetimes. Numerical modelling is widely used to optimize solar cells as it can predict the real-world behavior of a device. In this work, we present a numerical simulation of CsMAFA-based perovskite solar cells with monolayer graphene as the front electrode. The model is implemented in the COMSOL Multiphysics^® finite-element environment. Graphene is modelled using the Kubo formula to account for its frequency-dependent surface conductivity, and the electromagnetic wavs interface is coupled with the semiconductor module to capture optical–electrical interactions. The influence of absorber layer thickness on the current density is also examined by sweeping the perovskite absorber thickness (300–450 nm). The current voltage characteristic demonstrates higher current density (27 mA/cm²) at an absorber thickness of ~450 nm. Shockley–Read–Hall recombination (SRH) is studied inside the model and maximum recombination was found to be centred in the absorber layer. The graphene/HTL side shows an SRH recombination of 2 × 10²⁰ cm⁻³ s⁻¹, which is much lower than what is typically seen at ITO-based HTL interfaces. Full article

The commercialization of perovskite solar cells (PSCs) hinges on replacing toxic lead-based absorbers with environmentally benign alternatives while maintaining competitive power conversion efficiencies (PCE). However, the enormous parameter space governing lead-free device architectures—spanning absorber thickness, defect density, doping concentration, and charge transport layer (CTL) selection—renders traditional trial-and-error optimization impractical. This paper introduces PerovskiteOpt-AI, a machine learning (ML)-driven multi-parameter optimization framework that integrates SCAPS-1D device simulation with Gaussian process (GP) surrogate modeling and Bayesian optimization (BO) to systematically identify high-efficiency lead-free PSC configurations. A synthetic dataset of 12,000 device-level simulations generated for the FTO/WS₂/CsSnI₃/CuSCN/Au architecture by varying eight critical parameters. An ensemble of ML models—random forest (RF), XGBoost, and GP regression (GPR)—is trained and benchmarked, with XGBoost achieving an ${\mathrm{R}}^2$ of 0.9987 and RMSE of 0.041% for PCE prediction. The GP surrogate is then coupled with a BO loop employing expected improvement (EI) acquisition to navigate the design space, converging on an optimized PCE of 27.83% ± 0.21% within 150 iterations—a 38.6% relative improvement over the baseline. Shapley additive explanations (SHAP) analysis reveals that absorber defect density and perovskite thickness are the dominant efficiency drivers, while conduction band offset at the ETL/absorber interface governs open-circuit voltage. The proposed framework reduces the computational cost of full-factorial parametric sweeps by over 95%, establishing a scalable paradigm for accelerated, interpretable design of next-generation lead-free consumer-grade photovoltaic devices. Full article

This paper investigates the stability of perovskite films under bonding conditions, focusing on the impact of bonding temperature on the electrical, morphological, and elemental characteristics of perovskite solar cells (PSCs) incorporating a barium–strontium titanate (BST) barrier layer. This study aimed to elucidate the interdiffusion phenomena at interfaces and their effect on device performance. We found that increasing the bonding temperature significantly degrades PSC performance, with efficiencies dropping from 21% at 100 °C to 65% at 180 °C relative to unbonded devices. A critical bonding temperature of 150 °C was identified, which correlates with a pronounced drop in short-circuit current and a peak in series resistance, phenomena primarily attributed to severe elemental interdiffusion and defect formation at the interfaces. Morphological (SEM) and elemental (EDS) analyses confirmed the temperature-dependent nature of interdiffusion across the Au/BST/perovskite interfaces. These findings underscore the critical role of bonding temperature in triggering interfacial degradation, a factor that mediates the stability of BST-interfaced PSCs during packaging. Full article

The ambient stability of ambient-processed lead-free perovskite absorbers remains a critical challenge toward scalable, eco-friendly photovoltaics. Herein, we systematically investigate the time-dependent structural and morphological evolution of drop-cast ambient-processed Cs₃Sb₂I₉ thin films, being a potential non-toxic and stable solar absorber candidate (energy bandgap ~2 eV) for solar cells, stored under uncontrolled ambient condition (~60% Relative humidity) for 28 days. Sequential X-ray diffraction (XRD) and surface morphology analyses using scanning electron microscope (SEM) reveal that the films preserve their trigonal P$\overline{3}$m1 phase throughout aging, confirming phase stability. Moderate moisture exposure may induce partial recrystallization and subtle structural reorganization, possibly including minor c-axis realignment, leading to reduced lattice strain and improved crystallite coherence. Even after prolonged aging, no secondary phases or micro-cracks are detected, underscoring the slow degradation kinetics and robust Sb–I bonding that stabilize the layered [Sb₂I₉]³⁻ dimers. The late-stage increase in diffraction intensity and partial recovery of crystallographic parameters could indicate transient structural reorganization, potentially associated with moisture-mediated reordering within an overall degradation pathway. These observations suggest some degree of morphological persistence and structural tolerance of Cs₃Sb₂I₉ under ambient conditions, rather than complete stability. This behavior offers useful insights into ambient processing and the long-term reliability of lead-free perovskite photovoltaics. Full article

Vacancy-ordered double-perovskite Cs₂SnI₆ is known to be a good candidate for perovskite photovoltaics, as it is a light harvesting material which has potential both as an individual compound and as a component of a composite material. The compound is interesting due to being free of atom sites in B cationic positions, making the lattice “breathable” and giving it optoelectronic characteristics that vary with dopants. Here, antimony was examined as a possible heterovalent dopant with an ionic radius larger than that of Sn⁴⁺. In practice, it has been found that most of the materials are composites of Cs₂SnI₆ and Cs₃Sb₂I₉ phases. In the CsI–SnI₄–SbI₃ phase triangle, the melt crystallization process produced a layered (111)-oriented microstructure of crystallites with an increasing percentage of antimony. Two-dimensional perovskite materials look more promising in the decomposition of a solid solution to Cs₂SnI₆ and Cs₃Sb₂I₉ phases than in heterophase nucleation. The observed effect of (111)-oriented growth could be translated to other inorganic halides to form new oriented films or single crystals of perovskite materials. Diffuse reflectance spectroscopy showed an additional absorption shoulder in the NIR region for all groups of compounds, most likely induced by point defects in I sublattices of Cs₂SnI₆. Expanding the Cs₂SnI₆ absorption range to the NIR region could lead to new perspectives for its application. Full article

Terahertz radiation exhibits significant potential for communications, imaging, and spectroscopy. However, the development of efficient and low-cost THz detectors remains challenging due to limitations such as insufficient sensitivity, slow response speed, and poor room temperature stability. This work presents an innovative quasi-2D perovskite/Weyl semimetal (Co₃Sn₂S₂) heterojunction THz detector that combines complementary material properties via band engineering. The device achieves a remarkable responsivity of 374.15 A/W, a specific detectivity of 6.27 × 10¹¹ cm·Hz^1/2·W⁻¹, and a noise-equivalent power of 0.29 pW·Hz^−1/2 at 0.1 THz. This performance stems from the strong THz absorption of the perovskite layer combined with the high carrier mobility and topological surface states of the Co₃Sn₂S₂, which collectively enable ultrafast carrier extraction and suppressed interfacial recombination. This heterojunction design offers a novel strategy for high-performance terahertz detection and facilitates its integration into next-generation portable, integrated devices. Full article