Advanced Optical Materials最新文献

The luminescent efficiency of copper(I) halide cluster-based complexes is frequently diminished by multiple exciton recombination centers, which significantly restricts their optoelectronic applications. Herein, a mild structural rigidity-regulation strategy is proposed to suppress exciton recombination by organizing Cu_xX_x clusters with either the semi-rigid ligand bis(2-diphenylphosphinophenyl)ether (POP) or the rigid ligand 1,2-bis(diphenylphosphino)benzene (dppb). As a proof of concept, sandwich- or butterfly-like Cu_xX_x(L)₂ (x = 2 or 4; X = I or Br, L = POP or dppb) clusters with different structural rigidity and photoluminescence/radioluminescence performance are synthesized. Compared with Cu₄I₄(POP)₂, the Cu₂I₂(POP)₂ and Cu₂I₂(dppb)₂ clusters possess higher structural rigidity and form more compact stacks, effectively suppressing structural relaxation-induced non-radiative transitions during metal-to-ligand or halide-to-ligand charge transfer (M/XLCT). Notably, Cu₂I₂(POP)₂ and Cu₂I₂(dppb)₂ exhibit high photoluminescence/radioluminescence performance, achieving steady-state X-ray light yields nearly 150% higher than those of commercial LuAG:Ce. Furthermore, their corresponding flexible films demonstrate outstanding spatial resolution, reaching 11.5 and 14.0 lp mm⁻¹, respectively. This rigidity-regulation strategy can open a new avenue for the systematically designing of high-performance Cu_xX_x cluster-based X-ray scintillators.

Lead-free metal halide perovskites emerge as promising materials for ultraviolet (UV) photodetectors (PDs), addressing the challenges in cost, fabrication, and performance associated with traditional materials. Nevertheless, critical performance parameters such as responsivity, detectivity, and response speed remain substantially limited. This work demonstrates high-performance, self-powered UV photodetectors based on Cu₂AgBiI₆ (CABI) thin films, achieved through synergistic optimization of the photosensitive layer and interfacial layer. The incorporation of 15% chlorine (Cl) into pristine CABI markedly improves film coverage and crystallinity, reducing defect density and enhancing carrier mobility. Further interface modification with 0.25 m formamidinium iodide (FAI) synergistically refines film quality, leading to superior device performance. The resulting self-powered UV photodetector (CABI:15% Cl / 0.25 m-FAI) achieves a record-high specific detectivity of 3.20 × 10¹³ Jones at 365 nm, coupled with excellent stability and rapid response. This study offers valuable insights for developing high-performance, cost-effective, and solution-processable perovskite photodetectors.

Top-emitting quantum-dot (QD) light–emitting diodes (TE-QLEDs) are promising candidates for next-generation display technologies because of their high aperture ratio and compatibility with opaque substrates. However, their optical performance is limited by the intrinsically low transmittance of conventional semi-transparent metal electrodes. To overcome this challenge, a metal–insulator–metal color enhancement filter (MIM-CEF) is proposed as a top electrode to enhance the light outcoupling efficiency and narrow the spectral linewidth, thereby improving the color purity without causing carrier injection imbalance owing to changes in the functional layer thickness. The MIM-CEF operates via tunable microcavity resonance governed by the thickness of a poly(methyl methacrylate) spacer, which selectively amplifies the optical transmittance at target wavelengths. Photoluminescence measurements confirm that QD films integrated with the MIM-CEF exhibit significantly higher emission compared to their Ag electrode counterparts for both red and green indium phosphide (InP)-based QDs. In mixed red–green QD films, the MIM-CEF simultaneously suppresses non-resonant emission and enhances the emission intensity and color purity at the resonant wavelength. Utilizing these properties, TE-QLEDs integrated with the MIM-CEFs demonstrates higher luminance and external quantum efficiency than conventional devices. Thus, MIM-CEFs offer a promising electrode platform for next-generation high-performance QD display technologies.

Photodetectors with broad-spectrum sensitivity and high responsivity hold significant potential for applications across various domains, including optical communication and imaging. 2D transition metal dichalcogenides (TMDs) exhibit promising prospects in the realm of broad-spectrum detection due to their distinct electrical and optical characteristics. These materials can be integrated through stacking to create van der Waals (vdW) heterostructure. Nevertheless, the inherent weak light absorption of such vdW heterojunctions limits their practical performance. In this study, a strategy is proposed to enhance the performance of vdW heterostructure by significantly improving light absorption through nanostructures with Mie-type resonance. A photodetector based on a MoTe₂/ReSe₂ heterojunction integrated with this Si nanostripe array (OA) achieves broadband photodetection spanning the visible to near-infrared spectrum (405–1550 nm), with a peak responsivity of 277 A W⁻¹ and a specific detectivity of 9.46×10¹² Jones at 532 nm. In particular, in self-powered mode, the responsivity of MoTe₂/ReSe₂ photodetector on the Si nanostripe optical array (4.58 A W⁻¹) is nearly two orders of magnitude higher than that on the Si/SiO₂ substrate. Additionally, the device exhibits a distinct polarization sensitivity (ratio of 2.2), attributed to the anisotropic optical properties of ReSe₂ flakes, and demonstrates high-contrast polarimetric imaging capabilities.

Structural colors offer a sustainable alternative to toxic pigments and dyes, yet their realization from lignin, the most abundant aromatic biopolymer, has remained elusive. Whereas cellulose has enabled a wide range of bio-based photonic architectures, lignin has primarily been explored in the form of colloidal nanoparticles. Here, a paradigm shift is demonstrated: vivid, tunable structural colors generated directly from ultrathin lignin films. By simply varying film thickness, a continuous color palette spanning the visible spectrum, overcoming the need for nanoparticle synthesis or self-assembly, is accessed. The films show high stiffness, modest angular dependence, and rapid humidity responsiveness, pointing toward scalable applications in coatings, sensors, and sustainable photonics. This work redefines lignin from an industrial waste product to a functional optical material, opening new directions in biomass-based coloration.

Passive radiative cooling is a promising technology for mitigating global warming by reflecting sunlight and radiating heat into the supercooled outer space. This approach has attracted increasing attention. However, achieving efficient light scattering typically depends on high-refractive-index inorganic materials, such as titanium dioxide. Despite its widespread application, recent research reveals that titanium dioxide may pose a potential carcinogenic risk. As a sustainable alternative, cellulose offers renewability, biodegradability, and biocompatibility. Inspired by the scale structure of the Calothyrza margaritifera beetles, all-cellulose-based highly scattering films are developed to overcome the intrinsic low refractive index of cellulose. These films consist of ethyl cellulose microspheres with optimized size and filling fraction as scattering centers and cellulose nanofibers as a supporting network to anchor these microspheres. Despite their ultrathin thickness (10 µm), these films achieved a reflectivity of 70%. When applied for passive radiative cooling, 300-µm-thick all-cellulose-based films reduced temperature by 8 °C during the day and 2 °C at night. The use of cellulose to achieve thinner, more efficient scattering materials while minimizing material usage, offering a sustainable and safer alternative to titanium dioxide as a scattering material. Such all-cellulose-based highly scattering films hold great promise for the fields of functional coatings, foods, and personal care products.

Photoluminescence properties are important for the application of exciton-polaritons. Photoluminescence from lower polariton is usually observed, whereas that from upper polariton is weak. In this study, the emission angle-resolved photoluminescence properties of the strongly coupled gold plasmonic nanoarray cavities and molecular aggregates of squaraine are investigated. Angle-resolved photoluminescence shows similar dispersion as that of reflectance, with strong PL from both upper and lower polariton branches. This is attributed to the direct relaxation of high-energy excited states to upper and lower polariton branches, followed by radiative relaxation. Weak exciton-vibration coupling and inefficient polariton-polariton interactions may account for the weak inter-branch, intra-branch, and polariton-exciton reservoir scattering. It is further found that the photobleaching rate of J-aggregate excitons is suppressed and accelerated under strong coupling for short and long irradiation times, respectively. This is due to the combined effects of strong coupling-induced polariton wavefunction delocalization and the effect of hot electrons in plasmonic nanoarrays, with the latter accelerating the photobleaching. This study provides insights for a controllable modulation of the photophysical properties of molecular excitons in strong coupling conditions.

Self-trapped exciton (STE) emission is an important luminous form in lead-free double perovskites (DPs). However, the STE emitting mechanism and its tunability remain a big challenge. Herein, Sb³⁺/Ag⁺ induced local structure engineering is developed to construct dual-STE states in the Cs₂NaInCl₆ DP for the first time. Experimental results and theoretical calculations verify that the broadband orange emission of STE1 is generated by breaking the forbidden transition due to the reduction of electron dimensionality caused by Ag⁺ alloying. Sb³⁺ doping, besides the blue emission arising from Sb^{3+ 3}P₁ → ¹S₀ transition, additionally induces distortion of [AgCl₆]⁵⁻ octahedra, thereby generating STE2 radiative recombination with broadband far-red emission. Importantly, an energy transfer channel from Sb³⁺ dopants to STE2 is identified, and the relative intensities of the two STEs can be tuned by adjusting Ag⁺ and Sb³⁺ concentrations. These findings deepen the understanding of the photophysical mechanisms of lead-free double perovskites doped with ns² electrons and provide a foundation for more effectively regulating their optoelectronic properties.

To use solar energy effectively, environmentally benign solid-state hydrogen storage materials are sought that are capable of releasing hydrogen under visible light irradiation. The gravimetric hydrogen capacity of layered hydrogen silicane (L-HSi) is quite high (3.44 wt.%). The optical bandgap of L-HSi is 2.13 eV, which corresponds to a wavelength of ≈600 nm (green-to-yellow region). Here, visible-light-driven hydrogen release from L-HSi is reported. The action spectrum of L-HSi for hydrogen release is consistent with its absorption spectrum, indicating that hydrogen release is driven by bandgap excitation rather than the photothermal effect. The quantum efficiency of hydrogen release is 7.3% at 550 nm. Hydrogen release from L-HSi can occur under both inert gas conditions and in the dispersed liquid form. The light intensity dependence indicates that hydrogen release is driven by low-intensity light such as sunlight or a light-emitting diode. L-HSi is expected to be used as a safe, solid-state, and lightweight hydrogen carrier with low energy consumption for hydrogen release.

Eliminating lattice disorder in quantum dots (QDs) is critical for achieving high-performance quantum dot light-emitting diodes (QLEDs), as such disorder directly disrupts the uniformity of elemental distribution and degrades their optical properties. Here, a tertiary amine-mediated synthesis strategy is reported that utilizes nucleophilic reagents to regulate the coordination kinetics of cationic precursors during the growth of ZnCdSeS/ZnS QDs. This strategy leverages nucleophilic reagents bearing uncoordinated lone-pair electrons to stabilize the cationic precursors and modulate the QDs surface energy of highly reactive crystal planes, thereby promoting atomic-scale uniform growth of the QDs, minimizing lattice mismatch, preventing stacking faults, and thus enabling the synthesis of strain-graded QDs (sg-QDs). Consequently, by achieving precise control over both elemental distribution and lattice ordering in multicomponent alloy QDs, sg-QDs are obtained that exhibit a photoluminescence quantum yield of 98% in solution and 95% in the solid film. The sg-QD films further demonstrate monoexponential decay kinetics and reduced defect density, confirming effective trap-state suppression. The resultant green QLEDs achieve a record external quantum efficiency (EQE) of 25.2%, an operational lifetime of 1 925 900 h, and sustained EQE over 20% across a luminance range of 10²–10⁵ cd m⁻². This nucleophile-coordination paradigm redefines the synthesis of alloy nanocrystals, providing a dual-advantage platform for ultrastable optoelectronics and scalable QLEDs manufacturing.