材料科学

Metal halide perovskites have emerged as promising semiconductors for light-emitting diodes (LEDs) owing to their excellent luminescence properties1. However, their performance remains limited, primarily owing to the inherent contradiction between 'high crystallinity' and 'small size' in the in situ synthesis of perovskite nanocrystals on substrates. Here we report efficient blue perovskite LEDs (PeLEDs) achieved via in situ polymerization-driven nanocrystal confinement to synthesize perovskite films composed of high-quality nanocrystals. The in situ-formed polymer network imposes nanoscale spatial constraints during perovskite nanocrystal growth, enabling nanocrystals with small sizes and a high photoluminescence quantum yield of 83%. Furthermore, polymerizable monomers with sufficient coordination sites allow a prolonged lattice rearrangement of perovskite clusters, promoting the crystallinity of the nanocrystals. The synthesized perovskite nanocrystals are utilized in the fabrication of PeLEDs, resulting in an external quantum efficiency of 21.8% at 491 nm, which is among the highest performances in blue PeLEDs. This work simultaneously controls the thermal dynamics of perovskite crystallization and organic ligand reactions, which helps to advance understanding of the effect of ligand engineering on nanocrystal synthesis, benefiting the development of efficient PeLEDs and other optoelectronic technologies.

Perovskite-type oxides are among the most promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their mixed ionic-electronic conductivity and compositional flexibility. Many high-performance cathodes rely on Sr substitution at the A-site, often associated with surface segregation and long-term degradation. In this work, we explore an alternative strategy based on defect engineering and phase interactions in Sr-free composites. Perovskite-fluorite composites based on LaFe0.8Co0.2O3 were synthesized through a one-pot route designed to promote the formation of a perovskite phase and a limited amount of fluorite-type ceria. This approach allows the introduction of small fractions of Ce into the perovskite lattice, favoring the cooperative coexistence with La-doped CeO2. Structural, microstructural and spectroscopic characterization indicates that Ce influences the crystallization pathway and composite defect chemistry. Variations in lattice parameters and Raman features suggest modifications of perovskite structure consistent with defect formation and lattice distortion. Reduction properties and electrical conductivity measurements indicate that Ce incorporation in the perovskite and oxide interaction affect charge transport and oxygen mobility. The electrochemical results demonstrate that the optimal trade-off between activation energy (Ea) and polarization resistance (Rp) is achieved for the sample, with a nominal cerium content, Ce/(La + Ce) of 0.16. Moreover, the electrochemical properties are found to correlate with the nominal cerium content, which regulates defect chemistry and the resulting composite composition. Overall, results suggest that the one-pot synthesis promotes beneficial interactions between the perovskite and ceria phases, allowing the development of Sr-free ferrite-based materials with enhanced functional properties, minimizing the amount of ceria in the composite.

Humidity performance of perovskites is critical for efficient fabrication and large-scale application of light-emitting devices as it directly influences the material stability, film quality and device lifespan. Herein, we propose an all-fiber strategy for dynamic monitoring of the humidity-induced perovskite/polyacrylonitrile (PAN) composite nanofibers. Pure-bromide quasi-2D perovskite nanocrystals are in situ synthesized and encapsulated in the PAN matrix on the optical fiber platform via an electrospinning technique, which ensure the luminescence stability of the materials in relative humidity (RH) above 50%RH. By wrapping the composite nanofibers around an excessively tilted fiber grating (Ex-TFG) to serve as a humidity-sensitive film, water molecules can rapidly penetrate the nanofiber matrix and interact with the perovskite material, allowing the transmission spectrum of the grating to accurately quantify their concentrations. Experimental results show that the humidity-induced variations in the complex permittivity of the quasi-2D perovskite/PAN composite nanofibers directly reduce the resonant amplitude of the transmitted modes of the Ex-TFG, achieving a top intensity sensitivity of 0.63 dB/%RH. This study introduces an efficient method for incorporating stable perovskites onto fiber-based devices, and also demonstrates a potential for humidity characterization of the luminescent materials through the real time fiber signal monitoring.

Defects, humidity, and uncontrolled crystallization remain critical limitations for the perovskite photovoltaic performance. Fortunately, these issues can be addressed through additive engineering. However, it remains a challenge to develop a simple and efficient additive with the corresponding functional groups to simultaneously solve these problems. Herein, this goal was achieved by incorporating 6-maleimidocaproic acid (6-MCA) into the perovskite precursor solution. The functional groups (C═O) of 6-MCA coordinate with undercoordinated Pb2+ ions, effectively passivating defects in the perovskite film. Concurrently, they regulate the perovskite crystallization process to improve the film morphology by suppressing pinholes, enhancing crystallinity, enlarging grain size, and lowering roughness. Additionally, the hydrophobic alkyl chain of 6-MCA improves the moisture resistance of the perovskite film. As a result, the devices modified with 6-MCA achieved a champion power conversion efficiency (PCE) of 23.74% (compared to 20.38% for the control), with a high open-circuit voltage of 1.167 V and negligible hysteresis. More importantly, the 6-MCA molecule further enhanced the light, thermal, and environmental stabilities of the devices.

The efficiency of perovskite solar cells has increased to a certified value of 27% over the past decade, benefiting from the superior properties of metal halide perovskite materials. However, their long-term operational stability is still far inferior to that of commercial crystalline silicon solar cells. A key source of this instability is field-driven ion migration in vertical architectures, along with the consequent degradation at the absorber-electrode interfaces. Compared with the widely investigated vertical structures, back-contacted (BC) perovskite solar cells-wherein both electrodes are positioned on the same side of the absorber-offer a unique route to suppress interfacial ion migration and thereby enhance long-term device stability. These advantages are especially pronounced when combined with single-crystal perovskites, which possess low charge trap densities, long carrier diffusion lengths, and high bulk ion migration barriers. Unfortunately, only a handful of research groups have participated in the development of single-crystal BC perovskite solar cells; thus, the advancement of this area lags far behind that of its vertical counterpart. Therefore, a review that discusses the recent developments and challenges of single-crystal BC perovskite solar cells is urgently required to provide guidelines for this emerging field. In this progress report, we first introduce the main growth methods of single-crystal wafers compatible with BC architectures, followed by an outline of the developmental history of BC perovskite solar cells. Finally, the core bottlenecks facing single-crystal BC devices and corresponding optimization strategies are discussed in detail.

Flexible perovskite solar cells (F-PSCs) offer a compelling solution to the intrinsic rigidity of silicon-based photovoltaics, enabling power generation on irregular surfaces. However, their practical application hinges on the perovskite layer's ability to concurrent thermal cycling, so as to match the deformability of polymer substrates. Different from the conventional lattice solidification strategy for rigid devices, we incorporate a fluorinated misplaced-dipole engineered repairable elastomer into the perovskite film, which enhances perovskite intergranular toughness and mitigates thermal stress fatigue cracks. The resultant perovskite film exhibits suppressed lattice thermal fluctuation, thereby boosting enhanced environmental resilience. Consequently, the optimized F-PSCs deliver a champion efficiency of 25.54%, versus 26.83% for their rigid counterparts. More importantly, the F-PSC demonstrates exceptional durability under harsh operational stresses, retaining over 90% of the initial PCE after 11,000 bending cycles and maintaining a comparable retention rate following 500 thermal cycles, paving the way towards for the long-lasting flexible photovoltaic devices.

Halide perovskites have emerged as a compelling material for a broad range of optoelectronic applications, including light-emitting diodes, phototransistors, light-sensing and imaging systems. To enable practical application and compatibility with existing consumer electronics, they must be integrated with heterogeneous electronic platforms, such as complementary metal-oxide-semiconductor chips or thin-film transistors. Such integration is pivotal for transitioning perovskite technologies from laboratory demonstrations to commercial applications. In this perspective, we summarize recent progress in the system-level integration of perovskite optoelectronics with driving backplanes, compare key performance metrics with industrial benchmarks, discuss major challenges, and outline future directions and application prospects for perovskite optoelectronics.

Transition-metal halide perovskites of the form CsMBr3 (M = Mn, Fe, Ni) are emerging as attractive lead-free alternatives for optoelectronic applications, offering composition-tunable electronic structures, strong light-matter interactions, and enhanced environmental stability compared with hybrid lead halide perovskites. Despite this promise, the reliable synthesis of phase-pure, highly crystalline CsMBr3 nanocrystals (NCs) remains challenging due to their pronounced sensitivity to reaction temperature, precursor reactivity, and surface-ligand chemistry. Here, we report a reproducible and optimized colloidal hot-injection strategy for the synthesis of CsMnBr3, CsFeBr3, and CsNiBr3 NCs, and systematically elucidate the influence of reaction temperature and growth time on their structural, morphological, and optical properties. X-ray diffraction confirms the formation of phase-pure hexagonal CsMBr3 (P63/mmc) across all compositions under optimized conditions. Transmission electron microscopy reveals uniform nanocrystal morphologies with narrow size distributions and well-resolved lattice fringes, indicative of high crystallinity. Optical studies, including UV-vis absorption, steady-state photoluminescence, and time-resolved photoluminescence, demonstrate composition-dependent absorption characteristics and exciton recombination dynamics, reflecting the role of the transition metal cation in tuning optoelectronic behaviour. Time-dependent UV-vis and XRD analyses further reveal notable ambient stability over one month, with structural and optical degradation becoming evident only after prolonged exposure beyond 46 days, demonstrating stability far superior to that of equivalent untreated or unencapsulated CsPbBr3 perovskite NCs. X-ray photoelectron spectroscopy confirms correct metal incorporation and stable metal-halide bonding environments, while thermogravimetric analysis uncovers distinct, composition-dependent thermal decomposition pathways. Collectively, this work establishes a clear structure-property-stability relationship for CsMBr3 nanocrystals and provides a robust synthetic framework for advancing next-generation, lead-free perovskite nanomaterials for optoelectronic applications.

Stable wide-bandgap (WBG) perovskites are essential for achieving highly efficient tandem photovoltaics. However, state-of-the-art tandem solar cells typically employ mixed-halide WBG perovskite, yet halide phase segregation remains a critical bottleneck. Here, we design a molecular confinement domain in which paired iodide-bearing organic ligands bind adjacent FA+ cations and are interconnected by a bifunctional diammonium linker, effectively suppressing halide segregation by constraining the dynamic motion of orientable FA+ cations at the surface and interfaces of wide-bandgap perovskites. The suppression of this motion effectively strengthens lead-halide (Pb-X) bond strength, reinforces the lattice rigidity, reduces lattice vibrational amplitude and increases halide ion migration energy barrier. As a result, I-Br mixed-halide segregation and defect evolution under prolonged illumination are effectively suppressed. Finally, the resulting mixed-halide WBG films exhibit low trap densities, improved carrier transport, and enhanced light/thermal stability. Such concept is applicable to both 1.68 and 1.78 eV perovskite, yielding efficiencies of 24.21% and 21.20% in single-junction cells, respectively. When integrated into silicon-based tandem cells, the device delivers an efficiency of 33.59%, alongside durable long-term stability with a T96 lifetime of 1000 h under continuous operation.

Dion-Jacobson (DJ) hybrid perovskites are considered as highly promising X-ray detection materials due to their high stability and short interlayer spacing. However, the large-scale commercial development of these materials is challenged due to severe ion migration at high voltage and lead toxicity. Here, we successfully obtained a DJ-type polar lead-free green hybrid perovskite (4AMPY)2AgBiBr8 (1) by inserting 4-aminomethylpyridine (4AMPY) aromatic diamine into 3D Cs2AgBiBr6, and achieved efficient and stable self-powered X-ray detection. Specifically, owing to the insertion of 4AMPY, 1 crystallizes in polar space group P21 and exhibits a significant bulk photovoltaic effect. Additionally, strong hydrogen-bonding interactions between 4AMPY and adjacent inorganic layers lead to an ultranarrow interlayer spacing of 3.09 Å. Meanwhile, the enhanced electron cloud density in aromatic diamines improves the charge transfer channel of 1 and enhances its X-ray detection performance. Therefore, among all DJ-type lead-free hybrid perovskites, 1 achieves record-breaking sensitivities of 661.4 and 9465.2 µC Gy-1 cm-2 at 0 and 100 V, respectively. Importantly, 1 exhibits excellent storage stability, with its sensitivity remaining at 97.5% (0 V) and 96.6% (100 V) of the initial value after three months. This work will greatly promote the development of polar DJ-type lead-free perovskite-based self-powered X-ray detectors.

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.

Image-guided surgery systems require precise fusion of fluorescence mapping and structural background imaging, yet current dual-camera system methods suffer from field-of-view misalignment and pixel offsets, risking millimeter-scale surgical errors. To address these challenges, we developed an fluorescence/background fusion single-pixel imaging system based on spectral-splitting perovskite photodetectors. By incorporating gradient-optimized wide-bandgap perovskite filter layers, the perovskite photodetector can achieve spectrally selective detection through efficient separation of 520 nm fluorescence signals (S1) from 450 nm backscattered light (S2). With a high signal suppression ratio (S1/S2) of 57 times of the optimized photodetector, the system achieves a low detection limit of 50 nmol/mL for sodium fluorescein aqueous solution. More importantly, the active single-pixel imaging architecture ensures perfect field-of-view and pixel-level consistency across multiple detectors' images, eliminating the need for complex registration algorithms or sophisticated dual-optical path designs. Finally, through in murine tumor experiments, we achieved precise real-time fluorescence-labeled tumor localization and tracking imaging, demonstrating the reliability of our developed system in fluorescence/background fusion imaging. This provides a fluorescence-targeting approach for medical imaging, demonstrating the utility of single-pixel imaging in advanced diagnostics.

Kinetically trapped perovskites offer a unique platform for controlling functional properties through non-equilibrium phase formation. Here, we report that a layered hybrid perovskite, CPA2PbBr4, exhibits an unusual kinetic trapping phenomenon where rapid cooling stabilizes a metastable polar phase (IV, Pna21) instead of the thermodynamic ground state. This compound displays a cascade of polar phases below 350 K: the room-temperature phase III (Cmc21), the metastable phase IV, and the low-temperature phase V (P21), all of which are noncentrosymmetric and polar. The polar order in each phase is characterized by distinct CPA+ cation orientations and PbBr6 octahedral distortions, giving rise to switchable dielectric response and second-harmonic generation (SHG). SHG studies reveal that thermal cycling suppresses SHG intensity of phase III without structural changes, attributed to generation of strain that limits coherence length. The material exhibits efficient broadband photoluminescence (PL) with strong thermochromism, arising from self-trapped excitons in the distorted lattice. Pyroelectric measurements and P-E hysteresis loops confirm spontaneous polarization values of 1.2-2.2 µC cm-2 across the polar phases. Our findings demonstrate that kinetic control of phase selection provides a powerful strategy for tuning polar order and multifunctional properties in hybrid perovskites, with implications for optoelectronic and photonic applications.

Latent fingerprint development on rough non-porous substrates using fingerprint powders remains challenging because surface microstructures reduce particle-adhesion selectivity and weaken the contrast between ridges and the background. In this study, Cs2NaBi0.6Er0.4Cl6 double-perovskite nanoparticles were prepared by a solvothermal method and investigated as fingerprint-development particles for latent fingerprints on frosted plastic substrates. Structural characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicated that Er3+ was incorporated into the host matrix and that the product consisted of spherical nanoparticles with smooth surfaces, relatively uniform particle-size distribution, and good dispersibility. Comparative experiments involving 40 categories of latent fingerprint samples showed that the Cs2NaBi0.6Er0.4Cl6 nanoparticles outperformed conventional powders in developing fingerprints on frosted plastic substrates. Quantitative grayscale analysis using Image J 1.53K and Origin 2024 further showed that the development contrast, expressed as the D value, reached 51.21 for sebum-rich fingerprints and 35.87 for oil-contaminated model fingerprints, both of which were higher than those obtained with the other three powders. Because the fluorescence of Cs2NaBi0.6Er0.4Cl6 under UV excitation was weaker than that of the commercial red fluorescent powder, we attribute the improved development performance mainly to selective adhesion of the particles to fingerprint residues rather than to fluorescence intensity alone. In addition, the material maintained good performance for aged fingerprints within 10 days and for developed fingerprints stored for up to 8 days. These results suggest that selective residue-affinitive adhesion, possibly assisted by the hydrophilic or moisture-affinitive nature of the ionic double-perovskite particles, plays an important role in improving fingerprint development on rough non-porous substrates. This study provides a physical perspective for latent fingerprint development on rough non-porous substrates and broadens the forensic-science application of lead-free double-perovskite nanomaterials.

Single junction perovskite solar cells (PSCs) have surpassed a photoelectric conversion efficiency (PCE) of 27%. However, inevitable interface defects from the preparation process have emerged as notorious barrier to further enhancing performance. In this study, we introduce the L-isoleucine (L-lle) to modify the buried interface between tin dioxide (SnO2) and perovskite in PSCs. The oxygen atoms on the carboxyl group (-COOH) of L-lle migrate upward and chemically bond with the uncoordinated lead ions on the perovskite surface, effectively anchoring the displaced lead ions. Concurrently, the downward movement facilitates esterification reaction with the hydroxyl groups (-OH) on the surface of SnO2, which enhances molecular cross-linking, expands interface contact, and improves the stability of L-lle at the buried interface. The efficiency of PSC devices based on L-lle exhibit a significantly higher efficiency than that of control devices (23.54%), reaching 26.15%. Furthermore, after 1200 h of long-term stability testing, the modified device can retain 92% of its initial efficiency, demonstrating outstanding operational stability.

Perovskite solar cells (PSCs) utilizing self-assembled monolayers (SAMs) as hole transport layers (HTLs) have been successful. However, the integrity of SAMs is frequently compromised by organic solvent-induced erosion during subsequent deposition of perovskite films. To overcome this critical stability issue without increasing fabrication complexity, we propose a novel strategy in which SAM molecules are directly doped into the perovskite precursor solution. The in situ doping approach effectively compensates for solvent erosion, thereby enhancing the SAM coverage, improving the perovskite crystallinity, and significantly reducing the trap density at the buried interface. Consequently, the optimized devices exhibit superior film quality and a more robust HTL/perovskite interface, yielding a power conversion efficiency (PCE) of 25.16% and enhanced thermal and light stability. This straightforward approach offers a promising pathway for the development of low-cost, high-performance photovoltaic technologies.

Two-dimensional (2D) hybrid perovskites have come into the spotlight for optoelectronic applications due to their numerous exceptional properties. However, the lack of efficient methods for controllable growth of large-scale and high-quality 2D perovskite single-crystal (PSC) arrays restricts their practical application in integrated optoelectronic devices, such as photoconductor-type photodetector integration. Herein, a polyvinylpyrrolidone (PVP)-assisted template-space-confined method is proposed for growing patterned 2D PSC microplate arrays, in virtue of which a series of 2D PSC microplates in various Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) phases, as well as tunable lateral size and thickness, can be achieved. It is revealed that coordination-bonding interactions between the carbonyl groups of PVP molecules and perovskite precursor ions contribute to the uniform and continuous growth of 2D PSC microplate arrays spanning 100 mm2 areas. Specifically, the (PEA)2PbI4 PSC microplate arrays synthesized with the optimal 4 wt % PVP concentration exhibit high-quality crystallinity and low defect/trap density. In consequence, the photodetector array based on as-grown (PEA)2PbI4 microplate arrays is demonstrated with excellent photodetection performance and low device-to-device variation. This method enables controlling and scaling up the growth of high-quality 2D PSC microplate arrays, which constitutes an important step toward large-scale and integrated optoelectronic systems.

The mechanochemical ball-milling process for one-dimensional copper-based perovskite-like halide Cs5Cu3Cl6I2 is recognized as a crucial pathway for scalable and sustainable production. However, crystal lattice defects are often introduced during synthesis, which promote non-radiative recombination and lead to performance degradation. Herein, a hydrogen-bond engineering strategy through NH4+ lattice doping was implemented to enhance the optoelectronic performance and stability of Cs5Cu3Cl6I2. Notably, the NH⋯Cl hydrogen bonds were successfully visualized for the first time in copper-based perovskite-like halides through independent gradient model and electron localization function analyses. Furthermore, the passivation model built upon density functional theory calculations and device simulations, confirmed the effective passivation of Cl vacancies and I-Cl anti-site defects by these hydrogen bonds, along with suppressed halide ion migration, resulting in a significant suppression of non-radiative recombination. Consequently, the photoluminescence quantum yield was boosted from 46.27% to 72.40%, along with a 21.42% prolongation of fluorescence lifetime and remarkable enhancement in blue UV-pumped phosphor-converted light-emitting diode luminous efficiency. This mechanistic framework is expected to provide valuable guidance for the development of high-performance copper-based perovskites.

Halide perovskites exhibit exceptional optoelectronic and catalytic properties but remain chemically fragile, rapidly degrading under moisture or alkaline conditions. Here, we introduce a synthesis-driven interfacial engineering strategy that stabilizes the intrinsically unstable lead-free CsSnBr 3 ${\rm CsSnBr}_3$ perovskite by coupling nucleation and heterointerface formation within a single liquid-phase hot-injection process. During crystal growth, sulfur-vacancy-rich MoS 2 ${\rm MoS}_2$ nanosheets conformally encapsulate CsSnBr 3 ${\rm CsSnBr}_3$ nanocrystals, forming coherent 2D-3D p-n heterojunctions that suppress Sn 2 + ${\rm Sn}^{2+}$ oxidation, limit moisture penetration, and enable directional charge transport. The resulting heterostructure exhibits a built-in potential of 0.67 V, generating an internal electric field that promotes efficient charge separation and enhanced redox stability. Under alkaline conditions, the synthesis-driven heterointerface sustains bifunctional water splitting in both freshwater and seawater for over 24 h without chlorine evolution or structural degradation. More broadly, this approach provides a generalizable synthesis paradigm for stabilizing moisture- and oxidation-sensitive halide perovskites, enabling their integration into chemically robust and electronically coupled systems for aqueous electrocatalysis and other demanding environments.

Perovskite solar cells (PSCs) face a critical challenge in balancing high power conversion efficiency (PCE) with operational stability, largely governed by the crystallization kinetics and facet configuration of perovskite films. Here, we report a kinetically segmented crystallization strategy mediated by a conformationally preorganized macromolecular regulator, cellulose 2,4,6-trichlorophenylcarbamate (3Cl-NC). Through multidentate coordination, 3Cl-NC establishes localized precursor-rich microenvironments that promote heterogeneous nucleation. During thermal annealing, this association transitions into a thermally activated dynamic coordination state that retards long-range precursor transport while maintaining local availability for controlled crystal growth. This segmented regulation suppresses metastable δ-phase accumulation and facilitates photoactive α-phase formation. Furthermore, 3Cl-NC thermodynamically stabilizes the high-Miller-index (210) orientation, establishing a synergistic architecture that intrinsically enhances lattice structural stability. Consequently, the resulting perovskite films exhibit higher phase purity, relieved residual stress, and suppressed ion migration, enabling devices to achieve a champion PCE of 26.59% (certified 26.29%) with improved long-term stability.