Advanced Optical Materials最新文献

The development of doped organic room‑temperature phosphorescent (RTP) polymers is hampered by the physicochemical incompatibility between hydrophilic hosts such as polyvinyl alcohol (PVA) and conventional hydrophobic phosphors. This mismatch triggers severe phase separation and lowers RTP performance. A molecular engineering strategy that addresses this challenge by introducing intrinsically water‑soluble phosphonium salt emitters is presented. The design combines a bromide counterion that enhances intersystem crossing with a bulky alkyl chain that suppresses aggregation‑induced quenching, while also guaranteeing seamless miscibility with PVA. This approach eliminates phase separation and yields highly efficient, full‑color RTP in doped films, with emissions tunable from 427 to 619 nm. The best performer shows an ultralong lifetime of 2.18 s and a quantum yield of 11.63%. Building on these properties, the versatility of the material in two key applications is demonstrated, namely high‑performance flexible displays and high‑resolution X‑ray imaging with a spatial resolution of 11.51 lp mm⁻¹.

Trivalent lanthanide (Ln³⁺) ions are used in numerous applications such as light-emitting diodes, optical lasers, night vision devices, and thermal imaging. It is well known that Ln³⁺ ions have low absorption and emission intensities. Therefore, these ions are incorporated into host materials to improve their luminescent properties. In particular, halide perovskites and their derivatives are good host materials due to their high absorption coefficient, high defect tolerance, and solution processability. Each Ln³⁺ ion has unique optical and electronic properties, with emissions spanning the ultraviolet, visible, or infrared spectrum. Direct excitation of Ln³⁺ ions is difficult because their f–f transitions are parity-forbidden, resulting in very weak absorption. To overcome these limitations, dopant ions or ligands are used as sensitizers that absorb energy through allowed transitions and then transfer it indirectly to the Ln³⁺ ions, enhancing their emission intensity. This review discusses the origins of the sharp emission lines in Ln³⁺ ions, provides an overview of their electronic transitions, explores various synthesis methods, and concludes with a discussion of their potential in advanced optical and optoelectronic devices.

Pure hydrocarbon (PHC) molecules, composed exclusively of carbon and hydrogen, exhibit excellent stability and hold promising potential for applications in optoelectronic devices. Herein, a series of PHC host materials are proposed, namely (R)-4′“”-(9,9′-spirobi[fluoren]-2-yl)-2,4′“-bi(9,9′-spirobi[fluorene]) (SP-2), (R)-4′”“-(9,9′-spirobi[fluoren]-3-yl)-3,4′”-bi(9,9′-spirobi[fluorene]) (SP-3), and (R)-4′-(9,9′-spirobi[fluoren]-4-yl)-4,4′'-bi(9,9′-spirobi[fluorene]) (SP-4), based on the parent molecule spirobifluorene (SBF), designed through different connection sites to achieve varying degrees of molecular skeleton distortion. The resulting isomers exhibit high singlet and triplet energy levels, a wide HOMO/LUMO energy gap, and favorable thermal stability. These outstanding properties strongly support their potential as host materials for phosphorescent organic light-emitting diodes (PhOLEDs). As a result, green PhOLEDs based on SP-2 achieved a high external quantum efficiency (EQE) of 24.7% with minimal efficiency roll-off, which ranks among the best EL performances reported for PhOLEDs based on pure hydrocarbon host materials. This demonstrates that tailoring the degree of conjugation and three-dimensionality through different linkage sites is effective in creating host materials that successfully balance charge transport and exciton confinement.

Persistent luminescence (PersL) materials hold immense potential for information storage and anti-counterfeiting applications. However, realizing non-volatile optical memory remains challenging. Herein, we design Mg₂GeO₄:Bi³⁺,Ln³⁺ (Ln = Tb, Eu) PersL phosphors via non-equivalent substitution engineering, where Bi³⁺ and Ln³⁺ ions deliberately occupy non-equivalent Mg1/Mg2 sites to create bistable deep traps. This strategy generates an ultra-broadband, high-density trap distribution, enabling strong photo/thermo-stimulated luminescence for recalling excitation-field temperatures. The trapped carriers exhibit temperature-dependent storage and release dynamics, allowing reconstruction of excitation thermal histories. Based on this unique behavior, reconfigurable optical memory anti-counterfeiting patterns in phosphor films are demonstrated. The trapping mechanism, validated by thermoluminescence and XPS spectra, reveals that carrier redistribution follows Fermi-Dirac statistics governed by the interaction between trap levels and thermal lattice waves. This work opens new avenues for non-volatile optical data storage with high security and spatiotemporal resolution.

Perovskite light-emitting diodes (PeLEDs) have demonstrated remarkable potential in the race for next-generation display technologies due to their outstanding optoelectronic properties. While significant progress is made in improving device efficiency, the device half lifetime (T₅₀) of PeLEDs still falls far short of industrial requirements. Green and red PeLEDs have achieved device half lifetimes on the order of thousands to tens of thousands of hours, whereas blue PeLEDs remain limited to several hundred hours, posing a critical bottleneck to commercialization. In this review, recent advances aimed at extending the device half lifetime of blue PeLEDs are summarized. Also, the key challenges are discussed that hinder the stability of blue-emitting devices. Finally, a brief outlook and conclusion on future research directions are provided for improving the lifetime of PeLEDs.

Manganese(II)-based (Mn²⁺) hybrid halides are promising lead-free red phosphors; however, achieving high external quantum efficiency (EQE) remains challenging due to spin-forbidden d–d transitions and nonradiative losses. A structurally rigid hybrid halide, (MAMP)MnCl₃·Cl [MAMP = 2-((methylamino)methyl)pyridine], is reported, comprising face-sharing [MnCl₆]⁴⁻ chains stabilized by N─H···Cl hydrogen bonds and π–π interactions from the organic cation. This structural framework suppresses nonradiative recombination, enabling bright red emission at 655 nm with an EQE of 43.9%. The internal quantum efficiency (IQE) reaches 70.8%, indicating efficient radiative recombination. The material also exhibits good thermal stability (T₅₀ = 390 K) and a strong luminescent response under X-ray excitation. Density functional theory calculations indicate a direct bandgap with dominant Mn 3d orbital character. Integration into light-emitting diode (LED) devices demonstrates practical utility, with a white-light LED showing excellent color rendering (R_a = 90.6, R₉ = 91.6) and a red LED maintaining stable spectral output. These findings establish a rational design approach for Mn²⁺-based hybrid phosphors in next-generation optoelectronic applications.

The development of highly efficient near-infrared (NIR) luminescent materials is essential for advancing next-generation compact light sources. Nevertheless, achieving efficient emission in the second NIR spectral window (NIR-II, 1000–1700 nm) remains a considerable challenge. In this study, a series of apatite-structured compounds R₅(PO₄)₃Cl:Mn⁵⁺ (R = Ca, Sr, Ba) is design and synthesize to systematically investigate the effect of host cation variation on the luminescence behavior of Mn⁵⁺. Density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectroscopy reveal that the incorporation of Mn²⁺ into Ba²⁺ sites is suppressed due to the substantial ionic radius mismatch between Mn²⁺ and Ba²⁺. As a result, Mn⁵⁺ ions preferentially occupy the P⁵⁺ sites, leading to the highest luminescence efficiency observed in Ba₅(PO₄)₃Cl:Mn⁵⁺. Furthermore, sintering in an oxidizing atmosphere notably boosts the luminescence intensity of Ba₅(PO₄)₃Cl:Mn⁵⁺, achieving a high internal/external quantum efficiency (IQE/EQE) of 86.9%/51.5%. Utilizing this optimized phosphor, a NIR-II phosphor-converted light emitting diode (pc-LED) is fabricated by coating it onto a red-light emitter (blue LED + red phosphor (Sr, Ca)AlSiN₃:Eu²⁺), resulting in a record NIR output power of 326.6 mW at 300 mA. As a compact NIR light source, this device demonstrates high potential for applications in infrared optical imaging.

In the quest for advanced memory systems that integrate high storage capacity with robust security, optical memory based on storage phosphors has emerged as a compelling solution. Here, a co-doped UV phosphor, LuAl₃B₄O₁₂:Bi³⁺,Gd³⁺, is presented for security optical memory applications. The phosphor can be effectively charged using UV mercury lamps, storing excitation energy in the form of trapped charges. Selective release of this energy as 312 nm UV emission is achievable through various stimuli, including heat, monochromatic light, and ambient lighting, enabling controllable data retrieval. The phosphor's broad energy distribution of multi-structure traps allows for multilevel readouts, facilitating high-density data storage. Additionally, it exhibits a daylight-stimulated UV readout and exceptional cyclability (>1000 cycles), ensuring reliable performance across various environments. These attributes position the phosphor as an excellent candidate for secure optical memory devices, where sensitive data can be securely stored and accessed only through specific stimuli, thereby enhancing protection against unauthorized access.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters have attracted considerable academic and industrial attention because of their narrowband emission, high photoluminescence quantum yields (PLQYs), and exceptional chemical and thermal stability. These characteristics make them highly promising for applications in ultra-high-definition (UHD) displays, as they enable organic light-emitting diodes (OLEDs) with high color purity, superior efficiency, and outstanding operational stability. Nevertheless, the development of highly efficient and stable deep-blue OLEDs remains a critical and unresolved challenge. Recent advances in blue MR-TADF emitters, based on boron/nitrogen-, nitrogen/carbonyl-, and indolocarbazole-type MR systems, have yielded exceptional performance, with full-width at half-maximum (FWHM) values below 30 nm and external quantum efficiencies (EQEs) exceeding 30%. Despite these achievements, persistent issues such as aggregation-caused quenching (ACQ), efficiency roll-off, and device stability continue to impede further progress in blue-emitting OLEDs. This review comprehensively summarizes recent developments in blue MR-TADF materials and devices, focusing on their molecular design strategies aimed at tuning emission color, mitigating ACQ, as well as improving device efficiency and operational lifetime. The discussed insights are expected to accelerate the development of high-performance, stable blue MR-TADF emitters for next-generation UHD display.

Photocatalytic ammonia synthesis has emerged as a sustainable alternative to the fossil-fuel-dependent industrial Haber-Bosch process, utilizing solar energy to convert atmospheric nitrogen and water into NH₃ under mild conditions. While this method significantly reduces CO₂ emissions, it faces challenges such as low nitrogen solubility in water and competition with the hydrogen evolution reaction, which hinder its efficiency and scalability. Here, a core-shell approach is employed to incorporate controlled-morphology plasmonic gold nanoparticles (AuNPs) into Ni-doped ZIF-8 metal-organic frameworks (MOF_S), forming a hybrid photocatalyst. In this design, AuNPs serve as the core, while the NiZIF-8 shell prevents nanoparticle agglomeration and facilitates enhanced nitrogen and proton transport to the AuNP surface during illumination. The Au@NiZIF-8 photocatalyst outperforms NiZIF-8 alone, benefiting from improved electron transfer, energy migration, and localized field polarization. These synergistic effects enhance nitrogen activation and stabilize reaction intermediates, significantly improving catalytic efficiency and selectivity. Furthermore, the catalytic activity remains stable across three consecutive cycles.