Advanced Optical Materials最新文献

GaN-based deep ultraviolet (DUV) optoelectronic devices have garnered considerable attention for applications in sterilization, biological detection, and optical communications. However, the performance of current DUV optoelectronic devices is limited by the insufficient DUV transparency of conventional electrodes. In this work, the epitaxial growth of degenerately Si-doped Ga₂O₃ films on GaN as a promising DUV transparent electrode is reported. The 0.5% Si doped Ga₂O₃ (n⁺-Ga₂O₃) films exhibit DUV transparency exceeding 85% in the spectral range from 280 to 400 nm wavelength. Such a high DUV transparency is attributed to the ultrawide bandgap of ≈5.0 eV of the n⁺-Ga₂O₃ film induced by the Burstein–Moss effect due to degenerate doping. Moreover, the n⁺-Ga₂O₃ film exhibits a very low specific contact resistance of 1.96 × 10⁻⁴ Ω cm² to GaN. High-resolution X-ray photoemission spectroscopic (XPS) study reveals that n⁺-Ga₂O₃ forms a type-II staggered band alignment with GaN with a low interface barrier of 0.15 eV and a narrow band bending thickness of a few nm. The small barrier, together with the degenerately doped Ga₂O₃ film, enables excellent electrical contact at the n⁺-Ga₂O₃/GaN interface and low contact resistance. This work demonstrates n⁺-Ga₂O₃ as a promising alternative for DUV transparent electrode for GaN-based DUV devices.

Organic room-temperature phosphorescence (RTP) materials with tunable emission intensity, lifetime, and quantum yield are vital for optoelectronics, bioimaging, and anti-counterfeiting. Herein, a solvent-mediated hydrogen bond-driven self-assembly strategy is reported to regulate the RTP performance of assemblies derived from melamine (MA), cyanuric acid (CA), and 3,5-dicarboxyphenylboronic acid (IB). Protic (H₂O) and aprotic (dimethyl sulfoxide, DMSO) solvents modulated the assembly process, leading to a gradual transformation from defect-rich nanocrystalline assemblies with weak RTP to highly ordered crystalline assemblies with enhanced phosphorescence. Increasing water content (from 0% to 100%) of the mixed solvent of H₂O and DMSO could continuously improve the crystallinity and RTP performance of the material, with phosphorescence lifetime extending from 0.81 to 1.18 s and phosphorescence quantum yield rising from 1.73% to 11.93%. Notably, reversible modulation of RTP emission could be achieved through vapor stimuli, where alternating exposure to H₂O and DMSO vapors induced repeatable enhancement and attenuation of phosphorescence. The universality of this strategy is further demonstrated using additional phosphor guests. These findings highlighted the potential of solvent-mediated hydrogen-bonded assemblies as adaptable platforms for stimulus-responsive RTP materials.

The design of advanced materials often reveals how apparent imperfections, such as structural defects or impurities, can be transformed into functional advantages. In insulating oxide matrices, the controlled introduction of dopant ions is the first step toward efficient photoluminescence. Later, the engineering of additional defects, often detrimental for photoluminescence, gives rise to unique capabilities for optical energy storage and persistent luminescence. Initially driven by biomedical applications, nanomaterials currently occupy a central role in persistent phosphor research. However, elaboration processes allowing to preserve their nanoscale usually involve poor control over their crystallinity, leading to performance behind that of bulk materials. Developing nanophosphors with well-defined morphology and energy levels engineered for tailor-made and efficient energy storage presents a significant materials challenge. Yet once again, what seems a limitation may prove to be a powerful opportunity. By exploiting the nanoscale to engineer energy storage in an unprecedented manner, persistent nanophosphors can open a new era in advanced optical materials. This perspective highlights how emerging applications, progress in nanoscale synthesis, surface engineering, and integration into advanced architectures are opening the path toward multifunctional, application-ready materials. Altogether, the nanoscale offers a transformative avenue that can enable persistent nanophosphors to outperform their bulk counterparts.

Phosphor-sensitized fluorescent (PSF) mechanisms offer a promising route toward efficient and stable deep-blue organic light-emitting diodes (OLEDs) by converting long-lived triplets into short-lived emissive singlets through energy transfer. However, the PSF architecture—combining a phosphorescent (PH) sensitizer with a multiple-resonance (MR) thermally activated delayed fluorescent (TADF) emitter within a co-host matrix—introduces intertwined excitonic processes that obscure the origins of degradation. Here, cryogenic photoluminescence spectroscopy, together with multichannel exciton-kinetic modeling to disentangle these processes, is employed. This analysis reveals that degradation is primarily driven by dissociation of the MR emitters, triggered by high-energy triplet accumulation. Further, it is shown that MR emitter stability is markedly improved when the activation energy for reverse intersystem crossing is increased and when Förster resonance energy transfer from the PH sensitizer to the MR emitter outcompetes Dexter energy transfer. Guided by these insights, a deep-blue PSF OLED (CIE_y ≤ 0.15) with an operational lifetime of T90 = 141 h at 1000 cd m⁻², far exceeding unoptimized devices (35 and 108 h) is demonstrated. This work provides the first quantitative identification of the excitonic processes governing PSF OLED stability and establishes molecular and device-level design rules for long-lifetime deep-blue OLEDs.

Inspired by the remarkably high efficiency of the human retina, neuromorphic image sensors are attracting more and more attention. As the core component for optoelectronic conversion, optoelectronic synapses are hotly pursued under the stimulus of monochromatic light, limiting the capability of full-color imaging in one active cell. Herein, by leveraging the outstanding broadband photoresponse and distinct wavelength-dependent temporal current evolution, a neuromorphic multicolor image sensor is demonstrated based on oxygen-vacancy-mediated amorphous Ga₂O₃ (a-Ga₂O₃) thin film. Typical synaptic functions, including paired-pulse facilitation and the learning-relearning process, have been successfully mimicked under different light illumination. A 10×10 imaging array well identifies multicolor patterns under raster scanning of focused laser beams of 638, 520, and 405 nm, which is enabled by the combination of distinguishable photocurrent levels and memorizing/fading time of the final pictures among different wavelengths. The underlying mechanism of the visible photoresponse is further explored through scanning photocurrent microscopy measurement, suggesting the synergetic role of optical and electric fields on the dynamic behaviors of the photo-induced carriers assisted by the V_O-related sub-bandgap defects. This work provides a strategy to encode the color information in the time domain, offering a potential solution to construct a compact filter-free machine vision system in the future.

Rapid, instrument-free detection of mercury ions (Hg²⁺) is critical for addressing environmental emergencies, yet current methods face limitations in poor portability and sensitivity. Herein, a deep learning-optimized paper-based kit that incorporates controllable turn-off fluorescence of metal halide perovskite for instrument-free time-critical Hg²⁺ detection by the dynamic quenching mechanism and ensures visual discernment at 2 ppb, achieving a 1000-fold sensitivity improvement over commercial strips is presented. Furthermore, a smartphone app powered by the deep learning model (MobileViT) further optimizes sensitivity, achieving ultrasensitive quantification (0.11 ppb limit of detection) across a 0.2–200 ppb linear range (R² = 0.987) with 98% overall accuracy, and the whole detection is completed only within 5 min. This approach of instrument-free time-critical Hg²⁺ detection anticipates a new paradigm for rapid and on-site Hg²⁺ monitoring in environmental and industrial settings.

All-inorganic halide perovskites, such as Cs₄PbBr₆/CsPbBr₃, exhibit excellent optical properties and intrinsic stability as 0D materials, rendering them attractive for photonic applications. However, the vulnerability of these materials to moisture and heat necessitates the implementation of stabilization strategies. Conventional solution-based methods, such as doping or surface passivation, often require solvents that reduce uniformity and degrade optical performance. To overcome these limitations, a solvent-free powder atomic layer deposition (PALD) technique to coat Cs₄PbBr₆/CsPbBr₃ powders with conformal Al₂O₃ nanolayers is employed. The PALD-grown layer effectively passivated surface defects, suppressed Br vacancies, and stabilized the crystal structure of the perovskite in steam and polar solvents and under heat exposure. Importantly, relative photoluminescence quantum yield increased by up to 14% compared to the uncoated powders. Based on these strategies, it is fabricated a UV-responsive photoluminescent film by integrating Al₂O₃-coated Cs₄PbBr₆/CsPbBr₃ (green emission under UVA/UVB) with Al₂O₃-coated Cs₂Cu₃I₅ (blue emission under UVB/UVC), achieving clear wavelength-discriminable emissions, i.e., green, sky blue, and deep blue under UVA, UVB, and UVC illumination, respectively. This study demonstrates the potential of PALD as a scalable, solvent-free passivation method that enhances the environmental stability and optical performance of halide perovskites, thereby improving their commercial viability for use in next-generation optoelectronic devices.

Color-tunable organic light-emitting diodes (OLEDs) hold great promise for next-generation photonic applications, including intelligent lighting, advanced anti-counterfeiting systems, and adaptive displays. In this study, an innovative design of color-tunable OLEDs based on tricomponent dual-exciplex systems is proposed. By co-blending two donors (mCP and TCTA) with an acceptor (PO-T2T), two distinct exciplexes, a high-energy exciplex (mCP:PO-T2T, host) and a low-energy exciplex (TCTA:PO-T2T, guest), are simultaneously generated. This unique architecture enables voltage-regulated host-to-guest energy transfer: under low bias, efficient transfer leads to dominant guest emission, whereas at higher voltages the saturation of guest excited states suppresses energy transfer and enhances host emission. The design demonstrates broad architectural versatility, spanning from ternary co-doping (D_host:D_guest:A) to simplified blended-donor/acceptor bilayer (D_host:D_guest/A) and layered heterostructures (D_host/D_guest/A). Corresponding devices, T-0.03 (mCP:TCTA:PO-T2T = 0.97:0.03:1), B-0.1 (mCP:10 wt.%TCTA/PO-T2T), and L-0.1 (mCP/0.1 nm TCTA/PO-T2T), achieve CIE shifts of (0.04, 0.09), (0.06, 0.15), and (0.07, 0.14), respectively. Moreover, substituting TCTA with alternative donors (TAPC or TPD) further extends the color-tuning range, yielding shifts up to (0.08, 0.22) for TAPC-based and (0.14, 0.31) for TPD-based systems. These findings establish the tricomponent dual-exciplex approach as a universal and effective strategy for high-performance, voltage-tunable OLEDs.

Heterostructured nanointerfaces composed of ordered nanoparticles integrated with non-plasmonic functional materials offer broad application potential but remain limited by the lack of flexible and scalable fabrication techniques. This study presents a two-step top-down approach for constructing plasmonic architectures in neodymium-doped disordered crystals, enabling optical data inscription and encryption. Ion implantation is used to introduce nanoparticle precursors into the subsurface region of the crystal. Then, femtosecond laser-induced nonlinear near-field optical forces drive the redistribution of nanoparticles along the laser propagation path, facilitating the formation of ordered 3D nanoshell structures. By precisely tuning the laser irradiation power, the resonance modes of the hybrid system are modulated, allowing for controlled upconversion luminescence in rare-earth-ion-based plasmonic structures. The proposed method supports multifunctional optical applications, including data storage, encryption, and fluorescence/photoluminescence readout. This work establishes a general strategy for tailoring plasmon-enhanced optical responses in rare-earth-doped crystalline materials and can be used for opto-electronic and passive/active optical control.

Efficient solar-thermal conversion is crucial for applications including de-icing, energy harvesting, and thermal regulation in outdoor environments. However, most existing photothermal coatings suffer from limited light absorption and poor mechanical durability, leading to performance degradation under cold and low-irradiance conditions. Here, a durable ultra-black superhydrophobic coating is reported and fabricated through a simple spraying process, in which carbon nanotubes (CNTs), titanium nitride nanoparticles (TiN NPs), and a fluorocarbon silane are incorporated into a polydimethylsiloxane (PDMS) matrix. The resulting hierarchical micro/nanostructure exhibits an exceptionally low reflectance of 0.66%, excellent water repellency, and strong anti-icing capability. The micro/nanostructured surface morphology efficiently traps incident light, while the TiN and CNTs form a synergistic system where localized surface plasmon resonance (LSPR)-induced near-field enhancement significantly amplifies the photonic absorption, thereby improving broadband light harvesting and photothermal conversion. Under 1 sun irradiation, the coating rapidly heats to 70.1 °C, achieving efficient defrosting and de-icing. Even at −10 °C under 0.3 sun, the temperature rise is fourfold higher than that of TiN-free coatings. Moreover, TiN NPs enhance CNT dispersion and strengthen the filler-matrix interface, yielding excellent durability. This work provides a simple and scalable strategy for multifunctional photothermal coatings with reliable performance in energy-limited cold environments.