Advanced Optical Materials最新文献

Circularly polarized luminescence (CPL) in purely organic materials is limited by the almost exclusively electric nature of electronic transitions. Resolving this problem is possible through structuring organic materials at dimensions comparable to the wavelength of visible light. Here, the study explores the use of thin films made of chiral organic nanotubes for the enhanced induction of CPL. The study first performs multi-scale modeling of the chiroptical properties of organic nanotubes using the T-matrix method. Combined with chiroptical measurements, including Mueller matrix polarimetry, the study discusses the chiroptical properties of organic materials within the frames of their multi-scale structuring. When embedding aggregation-induced fluorogens (AIEgens) into the structured films, composites featured with gigantic g_lum factors reaching ≈10⁻¹ are obtained. Importantly, a series of control experiments is performed to exclude common parasitic effects that can lead to the apparent CPL signals. The enhanced chiroptical properties of the composite films of organic nanotubes and AIEgens enable visual discrimination of their handedness both in the absorption and emission realms. The uncovered multi-mode enhancement of CPL directs future endeavors for anticounterfeiting or holography applications.

The emergence of light-based technologies is revolutionizing modern medicine and healthcare by enabling precise disease diagnosis and treatment through various luminescent agents and imaging techniques. Despite challenges like biocompatibility, spectral tuning, and synthesis complexity, the primary issue is the aggregation-caused quenching of emission on high concentrations or physiological conditions. In light of these problems, Clustering-Triggered Emission (CTE), which involves the formation of atomic clusters to induce light absorption and the luminescence of unconventional chromophores, represents an all-in-one solution to the challenges identified. Given the potential for CTE materials to behave in ways previously only associated with conventional chromophores, it seems reasonable that highly oxidative reactive oxygen species can be formed from CTE excited states. The results demonstrate that it is possible to transfer the excess energy from the CTE long-lived excited states to molecular oxygen, thereby producing singlet oxygen. It is also noteworthy that over 99.9% of Staphylococcus aureus cells can be eradicated using fluences comparable to those used in traditional systems under violet light irradiation. Uncovering these photophysical properties of CTE opens the door to a revolutionary breakthrough that can disrupt conventional photodynamic therapy and usher in a new era of CTE-based photosensitizers.

Hybrid all-optical switching devices that combine silicon nanocavities and 2D semiconductor materials are proposed and demonstrated. By exploiting the refractive index modulation caused by photo-induced carriers in the 2D material instead of the silicon substrate, the switching speed limitation imposed by the carrier lifetime of silicon is overcome while maintaining a low switching energy. Air-mode photonic crystal nanobeam cavities capable of efficient interaction with 2D materials are fabricated, and molybdenum ditelluride, a 2D material with rapid carrier recombination, is transferred onto the cavities. The molybdenum ditelluride flake is excited by an optical pump pulse to shift the resonant wavelength of the cavity for switching operation. All-optical switching operations are achieved on the time scale of tens of picoseconds while requiring low switching energies of a few hundred femtojoules.

Obtaining high-performance films of organo-metallic halide perovskites is still a challenging task, with tremendous potential outcomes for devices involving light absorption such as next-generation photovoltaics or photodetectors. In many experimental reports, particularly on perovskite solar cells, the addition of metallic nanoparticles (gold, silver…) has demonstrated promising performance improvements. However, while light management strategies based on plasmonic resonances are the initial motivation for these experiments, various other explanations have been proposed and the plasmonic nature of the performance boost is not always clear. In this article, optical simulation analysis is combined with a general review of the experimental reports to elucidate the role of nanoparticles in perovskite devices from a multifaceted perspective. Performance improvements were recently reported for various devices (solar cells, photodetectors) of different perovskite materials where gold nanoparticles were introduced either by spin coating or evaporation. Alongside a comprehensive examination of conventional optical effects, a novel function is identified of nanoparticles in regulating the crystallization rate of perovskite films, leading to enhanced film quality and ultimately boosting light absorption and device optical performance. This analysis enriches the mechanistic understanding for future studies on the use of nanoparticles in perovskite-based devices, offering a novel approach for optimizing perovskite films.

Tunable optical devices are of paramount importance in modern optical engineering, offering the flexibility to dynamically adjust key optical parameters, thus enhancing functionality and adaptability. In this study, a fresh approach is presented to achieve on-demand, spatially tunable optical properties using organic mixed ion-electron conductors, which can be produced using large-scale, cost-effective technologies. It is demonstrated how, by exploiting, the spatial modulation of the bulk electronic conductance of PEDOT:PSS through an organic electrochemical transistor configuration, we can create a spatially tunable broadband gradient index profile with multiple degrees of freedom. These findings introduce a new class of tunable graded index media, which hold potential for a wide range of applications that span from optical interconnections to multi-focal optical devices.

Near-infrared (NIR) photodetectors are valuable technological devices with numerous uses, and transforming opaque NIR photodetectors into transparent ones will aid in the development of invisible interfaces for the rapidly emerging technology of human–computer interactions. However, transparent NIR photodetectors typically suffer from considerable optical loss, which reduces the device sensitivity. The current study enhances the trade-off between the transparency and sensitivity of NIR photodetectors by investigating the pyro-phototronic effect, which is accomplished using an ITO/Ag-Ag(O)/ZnO/NiO/AgNWs design. The design has a see-through feature with a visible light transmittance of 62.1%. An ultrathin Ag-Ag(O) layer absorbs NIR light, generating 476% more photocurrent because of the ZnO layer's pyroelectric effect. The pyro-phototronic effect allows ITO/Ag-Ag(O)/ZnO/NiO/AgNWs to be responsive to diverse NIR intensities with a response time of 0.18 ms. The metallic–semiconductor mixed-phase properties of the Ag-Ag(O) combination are produced by indirectly oxidizing embedded Ag nanostructures by adding oxygen during the ZnO layer development. The approach exploits the plasmonic effect of Ag nanoparticles, which improves the photothermal utilization of the ZnO layer, resulting in a stronger pyro-phototronic response at shorter wavelengths. Transparent sensors with high sensitivity and broadband operation would advance image processing and human augmentation.

Tandem organic light-emitting diodes (OLEDs) are an innovative and promising technology aimed at enhancing the luminance and extending the lifespan of OLED applications. A significant challenge in their development lies in achieving high-performance charge-generation layers (CGLs). In this study, the use of a yetterbium-silver (Yb:Ag) alloy is proposed as an assistant layer within the CGL to improve the injection of generated electrons into the electron transport layer (ETL). This enhancement is confirmed through capacitance–voltage measurements and work function analysis. Moreover, the Yb:Ag layer exhibits exceptional optical transmittance and surface uniformity. Tandem devices fabricated with the Yb:Ag alloy assistant layer exhibited a significant reduction in operating voltage, approximately halving it compared to tandem devices without a metal assistant layer. This resulted in a 2.13-fold increase in luminous efficiency and a 1.07-fold improvement in power efficiency compared to a single-unit device. Thus, the integration of a Yb–Ag alloy as a CGL assistant layer is a promising strategy for improving the performance and viability of tandem OLED technologies, underscoring its potential impact on next-generation displays and lighting applications.

An innovative, previously unexplored approach that leverages elastomeric membranes (EM) to develop a highly deformable cavity optomechanical resonator is proposed. This resonator generates multi soliton frequency combs (FCs) with low power consumption, a phenomenon of great interest in the realm of nonlinear light-matter interactions. This approach marks a breakthrough due to its streamlined simplicity, utilizing a single continuous-wave (CW) laser pump and an external acoustic wave. Matching the acoustic wave frequency with natural frequencies of the EM resonator accompanied by mechanical Kerr nonlinearities and dispersion give rise to the formation of mechanical FCs. The hyperelastic mechanical resonator and electromagnetic cavity resonance are parametrically coupled within the microwave frequency range, catalyzing the generation of mechanical FCs and their seamless transformation into optomechanical solitons within the optical domain with remarkable efficiency. Achieving stable pulse trains with a free spectral range ranging from 2 to 9 kHz using a few millimeter-sized cavity by supplying 2 to 4 mW pump power marks a pivotal advancement in chip-scale optomechanical resonators. This breakthrough holds transformative potential in domains such as quantum computing and spectroscopy. This method is fundamental to the creation of a mechanical Kerr medium, effectively bypassing the reliance on high mechanical quality-factors.

Multicolor emissive Schiff base lanthanide Poly(methyl methylacrylate) [PMMA] composite films are fabricated for white light generation. Three isostructural lanthanides (III) complexes [Eu^III₂(L)₂(NO₃)₂(dmf)₂ (1), Tb^III₂(L)₂(NO₃)₂(dmf)₂ (2) and Gd^III₂(L)₂(NO₃)₂(dmf)₂ (3)] are synthesized, characterized from the ligand obtained by 1:1 condensation of salicylaldehyde and 2-(2-Aminoethoxy)ethanol, H₂L. The photoluminescent studies revealed pure blue, green, and red color emissions from Gd^IIIL, Tb^IIIL, and Eu^IIIL complexes, although the central metal centers have identical dodecahedron geometry. Intensified ligand emission  is attested for the blue emitter-Gd^IIIL complex while the “antenna effect” is witnessed for green Tb^IIIL and red Eu^IIIL complexes. Co-doping these multicolor luminescent emitters into the PMMA polymer the intensity of luminescence improved. A conscientious combination of red-Eu^IIIL with green-Tb^IIIL Lanthanide metal Schiff base complexes in a specified concentration, distinct white light is accomplished for the first time with Commission Internationale de I’Éclairage (CIE) values of 0.33, 0.30, very close to the ideal white emitter. The newly developed lanthanide-Schiff base-PMMA composite films are transparent and highly desired materials in optoelectronics, microscopy, and sensing.

With the development and application of cryogenic technology, the demand for temperature measurement in cryogenic environment is increasing. Optical sensing can provide a non-contact method of temperature measurement in cryogenic environments. Herein, a new temperature measurement route based on the persistent luminescence is proposed. The single-component, coordination crystal Zn-ddcphpy with electron donor and acceptor structures, achieving persistent luminescence (6–7 s) after irradiating by ultraviolet light source at 80 K. The persistent luminescence decay and electron paramagnetic resonance show that the reason for the persistent luminescence generation is the photogenerated charge separation and recombination. In cryogenic environment controlled by liquid nitrogen (80–260 K), the persistent luminescence duration decreases with increasing temperature, the color gradually changes from green to yellow with the spectrum red-shift. Taking Zn-ddcphpy as a model material, the unquiet temperature sensitive based persistent luminescence shows convenience, intuitive and inexpensive. Furthermore, the LPL (long-persistent luminescence) of Zn-ddcphpy exhibits high sensitivity and responsiveness to temperature at cryonic environment, make it suitable for temperature measurement on real time. In this work, the change of duration and color can indicate temperature without contact, which can be used for temperature measurement and monitoring in the fields of cryogenic wind tunnels, cold chain storage, etc.