Advanced Optical Materials最新文献

Understanding how molecular packing governs solid-state fluorescence is key to unlocking new emissive materials. A comprehensive study of BODIPY derivatives with diverse substitution patterns is presented, showing how these modifications govern intermolecular interactions, packing motifs, and ultimately photophysical behavior in the solid state. Substituent effects dictate whether π–π stacking, hydrogen bonding, or halogen interactions dominate, resulting in distinct emission shifts and variations in fluorescence quantum yield. While increased chromophore overlap often leads to bathochromic emission, it also correlates with reduced quantum efficiency because of enhanced non-radiative relaxation processes. Notably, compounds with similar degrees of overlap can exhibit different emission profiles, underscoring the pivotal role of substituent-controlled packing. These insights provide a foundation for rational design of solid-state luminescent materials based on BODIPY scaffolds.

The development of blue-excitable deep-red phosphors represents a key advancement in next-generation agricultural lighting systems. Herein, a low-coordination polyhedral engineering strategy is proposed using novel K₃Y_1-xLu_x(BO₃)₂:Eu²⁺ to enable tunable broadband emission from 650 to 690 nm via Y³⁺→Lu³⁺ substitution, achieving blue-light-excitable deep-red luminescence that is uncommon among borate phosphors. Structural analysis reveals that Lu-induced lattice compression shortens the bond lengths in KO₆ and Lu/YO₆ octahedra, enhancing crystal field splitting and enabling deep-red emission with a full width at half maximum (FWHM) of 147 nm. Simultaneously, the photoluminescence quantum yield and thermal stability are significantly improved due to optimized Eu²⁺ site occupancy and suppression of non-radiative transitions. Density functional theory calculations and Hirshfeld surface analysis confirm that the shortened bond lengths and distorted polyhedra contribute to the enhanced luminescence properties. Prototype phosphor-converted LEDs based on K₃Lu(BO₃)₂:Eu²⁺ demonstrate excellent spectral overlap with chlorophyll and phytochrome absorption, accelerating wheat growth by 20% under tailored illumination. This work not only addresses the long-standing challenge of achieving deep-red emission in borate phosphors but also introduces a promising material for next-generation agricultural lighting applications.

The near infrared (NIR, >800 nm) or short wave infrared (SWIR) range of the electromagnetic spectrum overlays with the tissue transparency window and the telecommunication window, which makes it important for photonics.

Here, a persistent NIR tail and a feature at 923 nm is observed during the photochemical generation of singlet oxygen using various photosensitizers. This feature initially appears to originate from singlet oxygen as its energy fits to known higher order optical and vibrational transitions, and it occurs simultaneously with the characteristic singlet oxygen phosphorescence at 1275 nm. The emission is present under all photochemical conditions (photosensitizers, solvents, excitation sources and optical setups) but it is not observed for chemically generated singlet oxygen. Its intensity correlates with photosensitizer concentration (1 µM – 1 mM), excitation intensity, and the visible fluorescence intensity, but does not require the presence of oxygen.

A simulation shows that this feature arises from the NIR-tail of (visible) photosensitizer emission and the non-linear increase of detector sensitivities in the range between 900– 950 nm. At the same time, this signal correlates with photochemically generated singlet oxygen concentration. Thus, this NIR signal contains valuable information, but careful interpretation is required.

Although high-efficiency blue fluorescent TBPe-based organic light-emitting diodes (OLEDs) are reported, the microscopic mechanisms of excited states in TBPe emitters remain vague. Here, using fingerprint magneto-electroluminescence probing tools, hot excitons and their high-level reverse inter-system crossing (HL-RISC, S₁←T₂) and triplet fusion (T₂F, T₂+T₂→S_n→S₁) in TBPe are discovered for the first time, which is also consistently demonstrated by their transient-electroluminescence. Interestingly, all their rich microscopic physical behaviors can be reasonably explained within the framework of excited state dynamics involved in these TBPe-based OLEDs. The carrier mobility, polarity, and triplet energy of host materials can significantly affect the number of generated T_2,TBPe hot-excitons and thus the probabilities of HL-RISC and T₂F channels, which are further modulated by exothermic low-level Dexter energy transfer (DET) or endothermic high-level DET channels of cold or hot excitons. Moreover, utilizing the HL-RISC channel of hot excitons in TBPe dopants with the conventional low-level RISC channel of an exciplex co-host, a relatively high external quantum efficiency of 7.09% is achieved from blue fluorescent TBPe-doped OLEDs. Thus, this work renews the physical understanding of the microscopic evolution channels of excited states in TBPe emitters and lays a solid foundation for further designing high-efficiency blue fluorescent OLEDs.

The design and optical characterization of a plasmonic metasurface engineered to exhibit strong polarization anisotropy under both linearly and circularly polarized light is presented. The metasurface consists of geometrically asymmetric gold nanostructures arranged periodically on a glass substrate. Each nanostructure is formed by the fusion of three equilateral triangles. The nanostructures simultaneously break mirror and inversion symmetries, resulting in chiral and pseudo-chiral optical responses that manifest as linear and circular polarization-dependent spectral features. The numerical and experimental results reveal clear chiroptical effects in both near- and far-field. Near-field scanning optical microscopy confirms the excitation of polarization-selective localized plasmonic modes, with spatially distinct hot-spots lighting up under different incident polarizations. Furthermore, it is demonstrated that the metasurface exhibits a measurable enantiospecific optical response when coated with thin left- or right-handed chiral overlayers. The differential circular dichroism signals observed in the presence of opposite enantiomers highlight the potential of the metasurface for label-free chiral sensing. These findings provide new insights into the interplay between structural anisotropy, pseudo-chirality, and enantioselective interactions in planar plasmonic systems, highlighting their ability to emulate chiral optical behavior without requiring volumetric 3D structures.

Flexible perovskite solar cells (F-PSCs) have attracted extensive research attention due to their high power-to-weight ratios, low cost, and scalable production, as well as their potential applications in self-powered wearable devices, space photovoltaics, and the Internet of Things. The power conversion efficiency (PCE) of F-PSCs has increased remarkably to 25.44%, and their mechanical and environmental stability have also been substantially enhanced through advancements in the development of novel materials for each functional layer and interface, as well as the refinement of fabrication techniques. This review provides a systematic overview of recent progress in novel materials for obtaining high-quality functional layers and effective strategies for optimizing the interface between the charge-transport layer and the perovskite. The fabrication techniques from the laboratory to industrial production, as well as the potential applications of F-PSCs, are also discussed. Finally, the future prospects for the further development of F-PSCs are outlined, including the development of novel materials, the advancement of fabrication techniques, and the realization of commercial applications.

Chiral hybrid metal halides (CHMHs) have attracted extensive attention in the field of circularly polarized luminescence (CPL) due to their fascinating intrinsic chirality, simple synthetic method, and excellent photoelectric properties. However, it remains a huge challenge to simultaneously boost the CPL dissymmetry factor (g_lum) and the photoluminescence quantum yield (PLQY). In this study, a pair of non-emissive indium-based CHMHs, namely (R/S-C₅H₁₃NO)₃InCl₆, is first synthesized. Then, sequential incorporation of NH₄⁺ and Sb³⁺ ions progressively boosted self-trapped exciton (STE) emission. The resultant (R/S-C₅H₁₃NO)₂NH₄InCl₆:Sb (2-R/SInSb) not only achieves near-unity PLQYs but also exhibits remarkable g_lum of +9.4 × 10⁻³/−9.1 × 10⁻³. Experimental investigations reveal that the introduction of NH₄⁺ increases the distortion of metal-halogen octahedra, thus strengthening the STE emission. In addition, NH₄⁺ can modulate the distribution of hydrogen bonds around inorganic octahedra and chiral cations, which is conducive to the transmission and amplification of chiral signals. Based on the efficient CPL characteristics, 2-SInSb is further employed in a scintillation film, achieving a spatial resolution of 8.7 lp mm⁻¹ and high-quality X-ray imaging. These findings highlight the potential of indium-based CHMHs as high-performance CPL emitters and underscore their promise for X-ray imaging applications.

Materials and supramolecular structures with the ability to emit circularly polarized luminescence (CPL) are a necessity because they represent an advancement in photonic technologies for encoding, imaging, data manipulation, and chiral catalysis. However, current CPL materials often suffer from low luminescence dissymmetry and brightness, alongside sustainability challenges. This review discusses the emerging potential of biogenic molecules—specifically proteins, peptides, polysaccharides, and nucleotides—as a sustainable and effective strategy to tune and improve the CPL emission of natural or artificial organic chromophores. It highlights their structural advantages, such as hierarchical chirality, structural rigidity, and precise chromophore organization control, which significantly enhance CPL signals. Peptide-based assemblies are shown to leverage supramolecular interactions and chirality transfer mechanisms to amplify CPL. At the same time, fluorescent proteins utilize chromophore rigidity and exciton coupling to achieve a high CPL brightness. Nucleotide-based systems further showcase control over chromophore alignment, enabling dynamic and reversible CPL emission. Polysaccharides of different classes provide versatile, chiral scaffolds for inducing CPL through ordered aggregation and templating effects that can also be generated in vivo. Collectively, these biogenic approaches are key candidates for next-generation CPL-active materials.

The recombination rate and the exciton annihilation rates are crucial for understanding the exciton dynamics in organic light-emitting diodes (OLEDs). In this work, the recombination rate is determined from the relative carrier mobility estimated using a time-correlated single photon counting-based transient electroluminescence measurement. The estimation of the recombination rate from the carrier mobility for the thermally activated delayed fluorescence (TADF) emitter dimethyl-9,10-dihydropyridine-diphenyl sulphone (DMAC-DPS) and its blends helps to understand the effect of the host and dopants. The pristine devices show an enhanced recombination rate compared to the blended device, due to the high-field dependence factor estimated from the Poole–Frenkel behavior. Furthermore, the exciton–exciton annihilation rates in both systems are quantified using a kinetic model for optical excitation employing a global optimization method based on a genetic algorithm. The results indicate that in the blended DMAC-DPS system, the exciton–exciton annihilations are significantly reduced in comparison to the pristine system. Comparison of pristine and blended systems reveals the host–guest interactions governing recombination dynamics and exciton losses in practical OLEDs.

With the growing demand for smart sensing and information encryption technologies, stimuli-responsive luminescent materials are emerging as key candidates for temperature monitoring and security applications. This study presents a Mn²⁺-based hybrid halide, (MAMP)MnBr₃·Br [MAMP = 2-[(methylamino)methyl]pyridine], exhibiting reversible thermochromic luminescence, ideal for smart thermal sensing. The material undergoes a red-to-green emission shift triggered by a heat-induced coordination transformation, transitioning from octahedral [MnBr₆]⁴⁻ to tetrahedral [MnBr₄]²⁻ units. Upon heating to 455 K, the Mn-Br bonds are broken, leading to a structural transformation from octahedral [MnBr₆]⁴⁻ to tetrahedral [MnBr₄]²⁻. This coordination change causes a red-to-green luminescence shift (651–515 nm). The material delivers strong red emission at 651 nm with an internal quantum efficiency of 21.6%, exhibits high thermal stability, and demonstrates efficient X-ray scintillation. These properties make it suitable for non-contact temperature sensing and dynamic information encryption. The material's excellent performance opens new opportunities for applications in temperature history tracking, anti-counterfeiting, and flexible optoelectronic devices.