Advanced Optical Materials最新文献

In this work, an experimental study supported by numerical modeling that demonstrates the possibility of exciting Symmetry Protected-Bound states In the Continuum (SP-BICs) in a 1D silicon grating fabricated on a lithium niobate substrate is presented. bBoth transverse electric and magnetic polarization states are investigated, leading to the excitation of four quasi- Bound states In the Continuum (quasi-BIC) resonances, exhibiting distinct behaviors. Under standard illumination conditions (plane of incidence perpendicular to the 1D grating lines), two of these resonances are highly sensitive to illumination conditions, while the other two resonances involving unconventional illumination directions (plane of incidence parallel to the grating lines) are more robust to the angle of incidence, but just as sensitive to external stresses in terms of resonance wavelength and quality factor. Additionally, temperature detection is experimentally demonstrated with a Sensitivity of S_T = 0.81∼nm °C⁻¹, a state-of-the-art value achieved due to significant electromagnetic field enhancement inside the lithium niobate substrate at the quasi-BIC resonance. These findings pave the way for their use in various sensing applications (such as biology, electromagnetic, and temperature sensing), as well as nonlinear applications like second harmonic generation, and electro- and acousto-optic modulation.

Free carrier absorption (FCA) is established to be the cause of nonlinear losses in plasma-enhanced chemical vapor deposition (PECVD) silicon-rich nitride (SRN) waveguides. To validate this hypothesis, a photo-induced current is measured in SRN thin films with refractive indices varying between 2.5 and 3.15 when a C-band laser light is illuminating the SRN films at various powers, indicating the generation of free carriers. Furthermore, nonlinear loss dynamics is, for the first time, measured and characterized in detail in SRN waveguides by utilizing high peak power C-band complex shape optical pulses for estimation of free carrier generation (FCG) and free carrier recombination (FCR) lifetimes and their dynamics. Both FCG and FCR are found to decrease with an increase in the refractive index of SRN, and, specifically, the FCR lifetimes are found (92 ± 7) ns, (39 ± 3) ns, and (31 ± 2) ns for the SRN indices of 2.7, 3, and 3.15, respectively. Lastly, nonlinear losses in high refractive index SRN waveguides are demonstrated to be minimized and altogether avoided when the pulse duration reduced below the free carrier generation lifetime, thus providing a way of taking a full advantage of the large inherent SRN nonlinear properties.

Thermally activated delayed fluorescence (TADF) materials with the through-space charge transfer (TSCT) effects can provide a useful approach to efficiently utilize dark state triplet excitons through an efficient reverse intersystem crossing process. TSCT-TADF emitters PCzoTrz-ICz with small ∆E_ST values and high photoluminescence quantum yield is designed and synthesized using common acceptor triazine, donor 3,6-diphenylcarbazole and Indolo[3,2,1-jk]carbazole which is a rigid π-conjugated group with high triplet state and high thermal stability. The doped-organic light-emitting diodes using PCzoTrz-ICz as emitters exhibit high tolerance to host with different polarity and charge transport properties, and PCzoTrz-ICz doped devices in 2,8-bis(diphenylphosphoryl)dibenzofuran even realizes a maximum external quantum efficiency (EQE_max) of 32.5% and maximum current efficiency (CE_max) of 74.1 cd A⁻¹, which is higher than EQE_max of 28.1% and CE_max of 64.8 cd A⁻¹ of PCzoTrz. Moreover, PCzoTrz-ICz can be used as highly efficient sensitizers for narrow band blue emitter of v-DABNA, and achieves more than EQE_max of 33.3%, maximum luminance of 26,291 cd m⁻², CE_max of 42.7 cd A⁻¹ and blue index of 237 cd A⁻¹ CIE_y⁻¹.

Environment-benign ZnSeTe quantum dots (QDs) are regarded promising blue electroluminescent (EL) emitters alternative to Cd-based ones for the next-generation QD-display platform. Herein, the core/shell heterostructural variation of blue-emitting ternary ZnSeTe QDs by manipulating ZnSeTe core size (small versus large) and ZnSe inner shell thickness (thin versus thick), while ZnS outer shell thickness remains unaltered, is explored. EL outcomes of the resulting core/shell QDs having photoluminescence quantum yields of 59−80% within the blue color regime (454−463 nm) are found to be dependent on their heterostructural dimension, exhibiting the highest performances of 31709 cd m⁻² in luminance and 11.4% in external quantum efficiency (EQE) from large-ZnSeTe/thick-ZnSe/ZnS QDs. Furthermore, to address the chronic issues of excessive electron injection and exciton quenching at emitting layer/electron transport layer (ETL) interface, the surface of ZnMgO (ZMO) nanoparticle (NP) is modified by bicarbonate functional species. Bicarbonate passivation not only leads to the effective reduction of defective sites on the ZMO NP surface toward the suppression of exciton quenching but induces the upshift of ETL band alignment in favor of charge balance. As a result, the optimized blue device incorporated with bicarbonate-functionalized ZMO NPs delivers a peak luminance of 39739 cd m⁻² and a maximum EQE of 17.1%.

Rational design of chiral two-dimensional hybrid organic–inorganic perovskites is crucial to achieve chiroptoelecronic, spintronic, and ferroelectric applications. Here, an efficient way to manipulate the chiroptoelectronic activity of 2D lead iodide perovskites is reported by forming mixed chiral (R- or S-methylbenzylammonium (R-MBA⁺ or S-MBA⁺)) and achiral (n-butylammonium (nBA⁺)) cations in the organic layer. The strongest and flipped circular dichroism signals are observed in (R/S-MBA_0.5nBA_0.5)₂PbI₄ films compared to (R/S-MBA)₂PbI₄. Moreover, the (R/S-MBA_0.5nBA_0.5)₂PbI₄ films exhibit pseudo-symmetric, unchanged circularly polarized photoluminescence peak as temperature increases. First-principles calculations reveal that mixed chiral–achiral cations enhance the asymmetric hydrogen-bonding interaction between the organic and inorganic layers, causing more structural distortion, thus, larger spin-polarized band-splitting than pure chiral cations. Temperature-dependent powder X-ray diffraction and pair distribution function structure studies show the compressed intralayer lattice with enlarged interlayer spacing and increased local ordering. Overall, this work demonstrates a new method to tune chiral and chiroptoelectronic properties and reveals their atomic scale structural origins.

Nanomaterials have superior electronic, optical, and mechanical properties making them highly suitable for a range of applications in optoelectronics, biomedical fields, and photonics. Nanomaterials-based IR detectors are rapidly growing due to enhanced sensitivity, wide spectral range, and device miniaturization compared to commercial photodetectors. This review paper focuses on the significant role of nanomaterials in infrared detection, an area critical for enhancing night vision and health monitoring technologies. The latest advancements in IR photodetectors that employ various nanomaterials and their hybrids are discussed. The manuscript covers the operational mechanisms, device designing, performance optimization strategies, and material challenges. This review aims to provide a comprehensive overview of the current developments in nanomaterial-based IR photodetectors and to identify key directions for future research and technological advancements.

Herein, a design strategy is explored for thermally activated delayed fluorescence (TADF) materials by employing the meta-linkage of the spiral-donors 10H-spiro[acridine-9,9'-thioxanthene] (DspiroS) and 10',10'-dimethyl-10H,10'H-spiro[acridine-9,9'-anthracene] (DspiroAc) to the robust acceptor 2,4,6-triphenyl-1,3,5-triazine (TRZ). Two distinct TADF materials, m-DspiroS-TRZ and m-DspiroAc-TRZ, exhibiting unique photophysical properties and performance characteristics were synthesized. Interestingly, even subtle modifications in the molecular architecture can significantly impact the organization of materials in their aggregated state, thereby governing photophysical properties and inducing corresponding alterations in photoelectric characteristics. Notably, m-DspiroS-TRZ exhibits superior photophysical properties and exciton dynamics data, achieving a high photoluminescence quantum yield (PLQY) value of up to 95.9% and a rapid reverse intersystem crossing (RISC) rate (𝒌_{𝑹𝑰𝑺𝑪}) of 1.0 × 10⁶ s⁻¹. This positions m-DspiroS-TRZ as a potentially excellent terminal emissive and sensitizing host material, inspiring further exploration of its applications in electroluminescence. Consequently, TADF organic light-emitting device (TADF-OLED) and TADF-sensitized fluorescence (TSF-OLED) based on m-DspiroS-TRZ have achieved maximum external quantum efficiencies (EQEs) of 31.8% and 34.5%, respectively, demonstrating the significant versatile potential of m-DspiroS-TRZ.

Luminophores' dual emission (DE) properties hold great potential for realizing single-component white organic light–emitting diodes (WOLEDs). This study illustrates that the unique and vibrant DE phenomena with different luminous mechanisms can be formed through simple modulation of molecular structures. Four target luminophores, namely 2-TPE-PPI, 2-TPE-PI, 2-TPE-An-PPI, and 2-TPE-An-PI, capable of DE under different conditions, are intentionally designed and successfully synthesized. Owing to the inherent flexibility of the minor molecular backbone and minor steric hindrance, 2-TPE-PPI and 2-TPE-PI exhibit DE spectra in dilute solutions with different solvent polarities. The intrinsic cause of the DE phenomenon in 2-TPE-An-PPI and 2-TPE-An-PI arises from the localized distribution of frontier molecular orbits resulting from the presence of an anthracene unit and the formation of an exciter group through intermolecular interactions involving anthracene. Remarkably, single-emissive-layer WOLEDs based on 2-TPE-An-PPI and 2-TPE-An-PI demonstrate stable white emission with CIE coordinates at (0.33, 0.39) and (0.30, 0.39), respectively, closely approaching the CIE coordinates of standard white light. Moreover, they maintain stable EL spectra from 4 to 10 V, an exceptional attribute rarely observed in many white light devices.

Luminescent glass, as an important component of photonic materials, is extensively utilized in applications such as lasers and optical fiber amplifiers, which demand high quantum efficiency. To further enhance the surface emission performance of luminescent glass, this study introduces a novel approach by employing custom-made metal nanowires, applying them as coatings on the surface of Erbium-doped glass, rather than embedding traditional metal nanoparticles. Utilizing experimental techniques and Finite-Difference Time-Domain (FDTD) simulations, it is demonstrated that the surface-emission from Erbium-doped glass coated with silver nanowires or copper nanowire-graphene hybrids is significantly increased, showing an enhancement rate of up to 117.27% compared to intrinsic glass. Extended FDTD analysis reveals that variations in the size and density of the nanowires can optimize emission characteristics, thereby improving the emission performance of luminescent glass. The enhancement of the local electromagnetic field at the interface underscores the efficacy of metal nanowires in boosting photonic materials. This study not only highlights the practicality of metal nanowires in photonics but also introduces a rapid deployment pathway for customizing photonic interactions through nano-engineering, potentially extendable to other photonic materials.

Metal halide perovskite nanocrystals are sought after for many optical and optoelectronic applications, such as light-emitting diode and solar cells, due to their outstanding optical properties. However, their ionic nature makes them susceptible to ambient conditions. One rational solution to this challenge is the passivation or encapsulation of perovskite nanocrystals to isolate them from their environments. Thus, there is an urgent need to develop efficient methods for encapsulating emissive perovskite nanocrystals. A facile post-synthesis method is proposed to treat Cs_xFA_(1−x)PbBr₃ nanocrystals, in the presence of Fe³⁺ cations, to create a robust and water-stable nanocomposite structure, where 3D CsPbBr₃ nanocrystals are embedded in and thus protected by the 2D CsPb₂Br₅ nanosheets (named as CsPbBr₃/CsPb₂Br₅ hereafter). These Fe³⁺ cations facilitate the formation of the CsPbBr₃/CsPb₂Br₅ composite and regulate the growth of 2D CsPb₂Br₅ sheets. By performing controlled experiments, the possible mechanism of 2D nanosheet growth is proposed and discussed in detail. More importantly, the composite can remain stable in water for three months and exhibits amplified spontaneous emission under femtosecond laser irradiation. This work presents a synthesis pathway for producing durable perovskite composites that are promising for future lasing applications.