Advanced Optical Materials最新文献

The development of lead-free perovskites for optoelectronic applications remains a crucial challenge, particularly in achieving high performance at low operating voltages. Here, a 0D bismuth hybrid perovskite containing 2-(2-thienyl)pyridinium (TEP) as the organic cation, (2TEP)₄Bi₂I₁₀ (TTBI) is reported, that exhibits excellent photodetection capabilities and interesting thermochromic behavior. Single crystal X-ray diffraction reveals a structure featuring isolated Bi₂I₁₀⁴⁻ dimeric units with short I···I contacts (3.87 Å), promoting enhanced electronic coupling. Density functional theory calculations confirm a direct bandgap of 1.79 eV, while flash-photolysis time-resolved microwave conductivity measurements demonstrate a remarkably long charge carrier lifetime of 7.3 µs. Notably, photodetector devices based on TTBI achieve impressive performance metrics at an ultra-low bias voltage of 0.01 V, including a responsivity of 86 mA W⁻¹, a detectivity of 3.9 × 10¹² Jones, an on/off ratio of 10⁴, and an ultralow dark current of 1 pA. The material also exhibits reversible thermochromic behavior with bandgap modulation from 2.09 to 2.03 eV between 303 and 403 K, driven by thermal expansion and electron-phonon coupling, enabling dual-mode optical and thermal sensing. These findings, combined with excellent ambient stability, demonstrate the potential of TTBI as a versatile, environmentally friendly material for next-generation optoelectronic applications.

Projection multiphoton lithography (PMPL) is a promising alternative to conventional voxel-by-voxel serial writing lithography, offering significant gain in fabrication speed. However, this high throughput can come at the expense of geometric accuracy, as printed structures can deviate from the intended patterns displayed on the digital micromirror device (DMD). To uncover the origins of these deviations, a numerical framework is developed that solves coupled 3D reaction-diffusion equations and captures the underlying photochemical processes of projection-based printing. Simulations of elementary geometries such as circles and rectangles, which serve as building blocks of complex architectures, reveal that oxygen inhibition, oxygen diffusion from surrounding regions, and intensity variations due to DMD diffraction are the dominant sources of geometric distortion. Guided by these insights, pre-exposure and asymmetric compensation strategies are proposed that modify the projected patterns to counteract these effects. Simulations and experiments indicate that these approaches hold promise for mitigating distortions and improving the fidelity of printed structures, offering a pathway toward more accurate, high-throughput 3D microfabrication.

Transition-metal activators such as Cr³⁺ offer an exceptional platform for probing the interplay between crystal structure and electronic transitions in solid-state luminescent materials. Here, a composition-controlled La₃Sc₂Ga₃O₁₂: Cr system is demonstrated that undergoes a reversible transformation from a garnet (Ia$�\overline{3}$d) to a perovskite (Pm$�\overline{3}$m) structure through progressive Al³⁺ substitution. The resulting lattice contraction strengthens the octahedral crystal field around Cr³⁺, driving a transition from broadband near-infrared (NIR) emission (800 nm, ⁴T₂→⁴A₂) to narrowband deep-red luminescence (731 nm, ²E→⁴A₂). Structural refinements and spectroscopic analyses reveal a field-induced crossover between spin-allowed and spin-forbidden transitions, accompanied by suppressed electron-phonon coupling and a lifetime extension from microseconds to milliseconds. The configurational-coordinate model further links lattice vibrations to emission dynamics. Beyond mechanistic insight, the broadband NIR emitter enables nondestructive imaging, whereas the deep-red perovskite matches phytochrome absorption for plant photoregulation. This study establishes a unified structure-field-emission relationship and presents a general strategy for tuning broadband-to-narrowband transitions in transition-metal-activated oxides via crystal-field modulation.

There is extensive research interest in sustainable, high-performance persistent luminescent materials, featuring tunable organic afterglow and stimulus responsiveness, owing to their broad application potential. However, despite significant efforts by the scientific community, the value of single-phosphor systems in achieving efficient persistent luminescence through multiple responses is not widely recognized. This work constructs a supramolecular self-assembled system featuring multicolor phosphorescence, fabricated by incorporating (4-(pyridin-4-yl)phenyl)boronic acid (PB3) into a biomass-derived, macrocyclic β-cyclodextrin (β-CD) via multiple intermolecular interactions. Notably, the resulting PB3@β-CD assembly exhibits both excitation-dependent and visible-light excitation capabilities, with an excitation wavelength range spanning 240–420 nm. When excited by white light, the afterglow persists for up to 3 s. Furthermore, the coexistence of isolated and aggregated states of PB3 within the β-CD matrix causes the guest molecules to emit diverse afterglow colors under different excitation conditions. Compared to other matrices, PB3 in the β-CD matrix exhibits blue phosphorescence emission under 260 nm excitation and yellow-green phosphorescence emission under 360 nm excitation. It also maintains phosphorescence emission even at elevated temperatures (162 °C), a rare combination that significantly enhances functional diversity. The responsive nature of the biomass-based system enables the dynamic regulation of room-temperature phosphorescence (RTP) signals, supporting secure data processing.

Two-deimensional (2D) periodic structures such as frequency selective surfaces (FSS) are widely used for controlling the transmission, reflection, and scattering of electromagnetic waves. Applications including low-emissivity (low-E) glass for energy-efficient buildings and metasurfaces for reducing radar cross section (RCS) and infrared signatures require both frequency selective and low-E properties. This work presents a cost-effective methodology for a single-layer low-E FSS (SLLE-FSS) that satisfies these requirements. The design incorporates micro metal patches (MMPs), an array of metallic patches much smaller than the wavelength, which remain transparent in the RF band while reflecting most IR energy. By integrating MMPs within the same layer as the FSS, a high metal filling ratio is achieved without compromising RF characteristics. To address the computational cost caused by the scale difference between FSS and MMPs, equivalent circuit models (ECMs) are introduced for efficient design of both transmission- and reflection-type structures. The proposed approach is validated through simulations and measurements of MMPs, SLLE-FSS prototypes, and an SLLE-based artificial magnetic conductor (SLLE-AMC) for IR–radar bi-stealth metasurfaces. Results confirm that the methodology enables single-layer structures combining frequency selectivity and low-E properties, offering broad applicability to multifunctional electromagnetic and optical systems.

Persistent luminescent nanoparticles store excitation energy and emit photons long after stimulus removal, enabling background-free signals by minimizing tissue autofluorescence and the constraints of concurrent illumination. This review synthesizes recent progress in materials-level control of persistent luminescence and its biomedical use. This outlines mechanisms of charge trapping and release, then discusses strategies to modulate emission wavelength, intensity, and duration through defect engineering, trap-depth distribution, core–shell architectures, lattice/strain control, and surface modification. Recharge modalities spanning optical/near-infrared (NIR), X-ray, radionuclide, and ultrasound-coupled routes are compared with respect to penetration, safety, and in vivo practicality. Applications include high-contrast imaging, ultrasensitive biosensing, long-term cell tracking, optogenetic stimulation, and biophotochemical activation. Quantitative benchmarks are highlighted, such as afterglow half-life, integrated photon yield, NIR-I/II penetration, recharge efficiency, colloidal stability, biocompatibility, and clearance, and discuss manufacturing and standardization considerations. Finally, it outlines how machine learning can guide composition and defect design, predict trap landscapes, and accelerate optimization of these nanomaterials for translational studies.

Femtosecond laser irradiation induces a non-classical transition from 2D to 1D laser-induced periodic surface structures (LIPSS) on single-crystalline SrTiO₃ (STO). High-resolution characterization reveals this transition occurs with increasing pulse number—without changes in laser fluence or polarization state. The first few pulses produce initial cracks and 2D LIPSS through anisotropic lattice dynamics. Later, 1D LIPSS emerge, showing laser-polarization dependence due to periodic energy deposition from surface plasmon polaritons (SPPs)-laser coupling at specific incidence angles. Theoretical simulations confirm that periodic electromagnetic energy redistribution—caused by SPPs-laser interference—drives the transition, primarily due to incidence angle changes between the laser and preformed grooves. This work is crucial for understanding how multi-pulse interactions influence LIPSS formation, enabling better control in designing advanced nanostructured surfaces. It offers promising applications in optics, optoelectronics, photovoltaics, and biosensing.

As a carrier for mechanical-to-optical conversion, mechanoluminescent (ML) materials are driving innovations in anti-counterfeiting encryption, self-powered sensing, and human-machine interaction, with their core value lying in the transformation of “invisible mechanical forces” into “visible light.” However, current ML materials face challenges, including weak emission intensity, limited luminescence modes, and the absence of a unified mechanism for force-to-light conversion. Here, a high-intensity green ML phosphor, Ca₂GeO₄: Tb³⁺, visible under ambient light, is developed. Following pre-irradiation, excellent photoluminescence (PL) and persistent luminescence (PersL) are observed. Notably, tunable emission from blue to green is achieved in the PL through increasing the Tb³⁺ doping concentration, and PersL remained detectable after 1 h, suggesting applicability in delayed bioimaging and advanced anti-counterfeiting systems. Furthermore, it is revealed that the synergy between multiple trap levels and the piezoelectric field generated by lattice distortion induced by Tb³⁺ substitution for Ca²⁺ is identified as a key contributor to high intensity ML in Ca₂GeO₄: Tb³⁺, which is of significant importance for clarifying the force-to-light conversion mechanism. Remarkably, owing to its outstanding luminescent properties, the phosphors are integrated with polydimethylsiloxane (PDMS), demonstrating tremendous potential in multi-modal encryption, dynamic anti-counterfeiting, remote monitoring, and human-machine interaction.

The growing demand for next-generation lighting technology is driving efforts to develop white light-emitting fibers for potential applications in medical endoscopy, sensing, telecommunication, and integrated photonics. In this work, a new white light-emitting composite fiber based on YAG:Ce³⁺ phosphors embedded in a phosphate glass is developed. The glass matrix composition is precisely tailored to enhance the thermal stability of the glass to allow fiber drawing while matching the refractive index with the phosphors to ensure the transparency of the composite. Comprehensive analyses of the spectroscopic and structural properties reveal significant interfacial reactions between the glass and YAG:Ce³⁺ phosphor particles during composite preparation, including phase changes, elemental diffusion, and partial decomposition. Despite these effects, the YAG:Ce³⁺ phosphors retain their white light emission properties throughout both preform melting and fiber drawing. Light propagation in the fiber, despite the presence of the phosphors in the fiber, as well as white light emission upon blue excitation are demonstrated.

Compact Pixel Architecture via ACEL

The frontispiece shows a frequency-modulated, AC-driven quantum-dot electroluminescent pixel comprising tandem RGB stacks separated by a charge-buffer layer. Varying the drive frequency redistributes charge between the top and bottom stacks to yield smooth, reversible color tuning. This compact architecture approaches the DCI-P3 color gamut and simplifies full-color, ultra-high-resolution displays. More details can be found in the Research Article by, as reported by Shuai Chang and co-workers (DOI: 10.1002/adom.202502689).