Advanced Optical Materials最新文献

Achieving efficient optical coupling between the emission from perovskite quantum dots (PQDs) and photonic integrated elements requires ultranarrow linewidths and highly directional emission. These are challenging goals at room temperature due to the broad and isotropic nature of perovskite emission. Here, we demonstrate ultranarrow-linewidth emission from CsPbBr₃ PQDs at room temperature, in both spontaneous and stimulated regimes, by coupling to state-of-the-art open-access curved dielectric cavities under continuous wave excitation. The emission is confined to a single transverse electromagnetic mode of the cavity, achieving a remarkably narrow linewidth of 0.2 nm, ≈100× narrower than free-space emission in both the emission regime. Single-mode lasing from a small number of PQDs is observed, yielding a quality factor of ≈2590, among the highest reported for single-mode lasing. The open-access design enables precise tuning of cavity length and selective coupling of emitters in their native state, overcoming the limitations associated with closed and fixed-length vertical-cavity surface emitting laser geometries. The geometry's low divergence and tunability provide an efficient route for integrating perovskite emitters with on-chip photonic circuits, advancing their use in quantum and optoelectronic technologies.

Perfect fractional vortex beams extend the concept of perfect vortex beams by introducing non-integer orbital angular momentum (OAM) and exhibit distinctive phase discontinuities, thereby offering additional degrees of freedom for optical communication and particle manipulation. This work demonstrates a spin-multiplexing metasurface for generating perfect quasi-fractional vortex beams (PqFVBs). By integrating the phase functions of an axicon, a spiral phase plate, and a Fourier lens into a compact metasurface design, The platform enables the selective generation of PqFVBs under orthogonal circular polarizations. The experimental measurements confirm that the beam radius can be flexibly customized via the phase parameters, specifically, the focal length and numerical aperture, while remaining decoupled from the OAM value. Furthermore, through introducing controllable phase dislocations, the number of donut-shaped intensity lobes can be precisely engineered. Those structured optical vortices with customizable spatial distribution and topological features will open new avenues for optical communication and optical manipulation.

Gaining accurate control over surface temperature is vital in optoelectronics, photocatalysis, and biosensing. Thermoplasmonic techniques excel in regulating surface temperature, offering exceptional spatial resolution and thermal control. While most efforts focus on designing nanoscale temperature patterns via efficient light-to-heat conversion, an alternative: engineering thermal conductivity profiles around nanoantennas is explored to give an additional temperature control knob. In this work, the thermoplasmonic performance of regular gold nanoantennas has been optimized by the generation of an anisotropic thermal conductivity substrate. This consists of a thin film of silicon grown on a silica substrate where the heat generated at the nanoantennas can be diffused in-plane along the silicon layer while it is confined out-of-plane by the silica. the potential of this approach is numerically demonstrated for the design of temperature gradients by means of metasurfaces. Experimentally, the generation of homogeneous temperature patterns with the capability of diffusing heat away is demonstrated from the thermoplasmonic source. This makes a difference with respect to most approaches in literature where the shape of the thermal patterns is necessarily determined by the nanoantenna distribution. In addition, it shows the potential of this approach in applications that may require a large surface area of operation.

2D perovskites are widely recognized as promising candidates for X-ray detection. However, most 2D perovskites are organic-inorganic hybrids with low equivalent atomic numbers, limiting their X-ray absorption capacity, while all-inorganic 2D perovskites typically exhibit <110> orientation, suffering from severe structural distortion and poor carrier transport. To address these challenges, an all-inorganic sulfur-halide mixed perovskite, BiCuSCl₂, is proposed featuring a 2D <100>-oriented structure, and further enhance its performance via BiOCl heteroepitaxial passivation. The all-inorganic composition endows BiCuSCl₂ with a high equivalent atomic number across the entire X-ray energy range, while the <100> orientation minimizes structural distortion. Meanwhile, the epitaxial BiOCl layer effectively passivates grain boundary defects and suppresses ionic migration. As a result, the BiCuSCl₂ wafer detector achieves a significantly improved µτ product (from 1.98 × 10⁻³ to 7.76 × 10⁻³ cm² V⁻¹) and high resistivity (1.12 × 10¹¹ Ω cm). The optimized device exhibits an ultralow dark current density (6.32 × 10⁻¹¹ A cm⁻²) and a sensitivity of 219 µC Gy⁻¹ cm⁻² under identical bias. The realized specific detectivity (ratio of sensitivity to noise current density, 3.47 × 10¹² µC Gy⁻¹ A⁻¹) is among the highest all lead-free perovskite X-ray detectors.

Stable multi-resonance thermally activated delayed fluorescence (MR-TADF) blue emitters are an effective choice for organic light-emitting diodes (OLEDs), offering high colour purity and efficiency. Here, a stable B─N emitting core is developed through an asymmetric N-fusion strategy. This involved constructing a B─N emitting core on a robust carbazole backbone, which enhances structural rigidity and reduces the number of weak sp³ C─N bonds relative to typical DABNA emitters, thereby increasing the bond-dissociation energies of the anionic state. Additionally, the peripherally fused carbazoles yielded two emitters, namely, pCz-BN2 and mCz-BN2, exhibiting pure blue emissions at 457 and 459 nm in a toluene solution, with corresponding CIEx,y of (0.13, 0.07), and achieved high photoluminescence quantum yields over 95% for the emitters, respectively. The fabricated fluorescence OLEDs produce pure blue emissions at 459 and 463 nm, with maximum EQEs of 8.67% and 6.90% for pCz-BN2 and mCz-BN2, respectively, demonstrating minimal efficiency roll-off. Furthermore, the PSF-OLEDs emit blue light with high EQEs of 25.8% and 23.6%, respectively, with reduced roll-off. Significantly, the pCz-BN2-based Fl-OLED has attained a remarkable operational lifetime (LT₉₅) of 95 h at an initial luminance of 1000 cd m⁻², the longest reported among single-boron MR emitters to date.

Despite their amorphous character, vapor-deposited organic thin films can exhibit significant anisotropy in molecular orientation. When this anisotropy leads to the preferential alignment of molecular permanent dipoles, spontaneous orientation polarization (SOP) is observed. The resulting large polarization fields can impact film properties and device performance. In organic light-emitting devices (OLEDs), SOP can lead to interfacial polaron accumulation that can limit efficiency and operational lifetime. Solid-state dilution of the SOP-forming material with an additional molecular species has been previously demonstrated as a (often nonlinear) means to tune the magnitude of SOP. Here, emphasis is on the behavior of SOP in blends where both species separately exhibit SOP and can effectively transport charge. Interestingly, it is found that such polar-polar blends can show a linear dependence of the giant surface potential (GSP) slope on composition, allowing for straightforward tuning of SOP. Supporting density functional theory calculations suggest that the observed composition dependence of SOP may reflect the balance of competing intermolecular interactions, which can favor segregation versus more uniform mixing. These findings are applied to engineer SOP-induced quenching in OLEDs, highlighting the range of potential interactions that can be expected for SOP in blends and their usefulness to tune this phenomenon.

Inverse design in nanophotonics, the computational discovery of structures achieving targeted electromagnetic (EM) responses, has become a key tool for recent optical advances. Traditional intuition-driven or iterative optimization methods struggle with the inherently high-dimensional, non-convex design spaces and the substantial computational demands of EM simulations. Recently, machine learning (ML) has emerged to address these bottlenecks effectively. This review frames ML-enhanced inverse design methodologies through the lens of representation learning, classifying them into two categories: output-side and input-side approaches. Output-side methods use ML to learn a representation in the solution space to create a differentiable solver that accelerates optimization. Conversely, input-side techniques employ ML to learn compact, latent-space representations of feasible device geometries, enabling efficient global exploration through generative models. Each strategy presents unique trade-offs in data requirements, generalization capacity, and novel design discovery potentials. Hybrid frameworks that combine physics-based optimization with data-driven representations help escape poor local optima, improve scalability, and facilitate knowledge transfer. Data efficiency, transferable representations, fabrication-aware design, faster solvers, and hybrid multiphysics co-design are emphasized.

Achieving voltage-invariant color stability in white organic light-emitting diodes (WOLEDs) is a critical challenge hindering their practical application, especially in simplified, non-doped architectures. In this work, a highly-efficient, spectrally stable non-doped WOLED is presented by incorporating an ultrathin interfacial barrier layer of CzSi at the emission interface. This functional layer effectively confines excitons and stabilizes the recombination zone by suppressing electron leakage and excessive hole injection, thereby achieving excellent charge balance. The optimized bi-color device achieves a peak external quantum efficiency (EQE) of 18.8%, a current efficiency of 49.5 cd A⁻¹, and a maximum luminance exceeding 13,090 cd m⁻². Remarkably, the device exhibits minimal chromaticity drift (ΔCIExy = 0.003, 0.009) across a wide voltage range (4–10 V). Exciton recombination profiling and single-carrier transport measurements confirm that the CzSi layer functions as a bidirectional energy barrier, finely regulating charge recombination and spatial exciton distribution. Furthermore, this approach is extended to tri-color WOLEDs, which exhibit a high color rendering index (CRI) of 89 while maintaining excellent voltage-invariant emission. The dopant-free, minimalistic design offers a practical and scalable pathway for the development of high-performance WOLEDs with outstanding color stability and fidelity, paving the way for advanced display and solid-state lighting applications.

Achieving precise aqueous-phase modulation of circularly polarized luminescence (CPL) at the molecular level presents significant challenges due to the complex interplay required between chiral organization, emission regulation, and stimuli-responsive components. Herein, an ultrasensitive pH-responsive aqueous CPL inversion and amplification system is reported at the molecular scale through positional isomerism-engineered dynamic host–guest self-assembly. By synthesizing naphthalene-bridged bis(phenyl-vinyl-pyridinium) positional isomers and coordinating their complexation with carboxylated γ-cyclodextrin hosts, it is demonstrated that bridge substitution patterns dictate supramolecular chirality through conformation-specific binding geometries. Unique stoichiometric dependence reveals a ratio-responsive mechanism mediated by competitive supramolecular interactions with diverse chiroptical behaviors. Capitalizing on the pH-sensitive carboxyl groups of γ-cyclodextrin hosts, position-isomer-specific chiroptical responses are established within physiologically relevant pH variations between 5 and 6, achieving both 724-fold circular dichroism amplification and 0.01-level CPL inversion of dissymmetry factor. This work signifies a supramolecular decoupling strategy that opens a pathway for developing intelligent chiroptical materials, dynamic anti-counterfeiting systems, and bio-photonic devices.

The ultra-long room temperature phosphorescent (ULRTP) organogels with multiple signal outputs are rare, despite of their promising applications in sensing and security due to their exceptional sensitivity to analytes and external stimuli. In this study, three methoxy groups are introduced into a previously reported carbazole-based ULRTP organogelator. It is discovered that the methoxy units enhance intermolecular interactions, which facilitates gelation. Additionally, the new gel demonstrated ULRTP with time-dependent afterglow and temperature-sensitive phosphorescent properties. A detailed investigation reveals that trace impurity from commercial carbazole is responsible for the ULRTP and time-dependent phosphorescence. The temperature-sensitive ULRTP and time-dependent afterglow properties of the gel make it a promising candidate for multi-level security applications.