Advanced Optical Materials最新文献

Lead-based perovskite light-emitting diodes (PeLEDs) is gaining significant attention for their outstanding optoelectronic properties. However, the intrinsic lead toxicity in these materials presents serious environmental and health risks, limiting their further development. Here, highly efficient zinc-lead alloy quasi-2D perovskites are developed through Zn²⁺ substitution and additive engineering. The Zn²⁺ substitution improves tolerance factors, increases radiative recombination rates, and suppresses nonradiative recombination, thereby enhancing stability. Additionally, [bis(4-methoxyphenyl) phosphinyloxy]carbamic acid tert-butyl ester (BPCA) additive effectively passivates bromine vacancy defects and improves film quality. The successful Zn²⁺ substitution and additive passivation strategy results in a significantly increased photoluminescence quantum yield from 4.3 to 85.6%. Consequently, high-performance zinc-lead alloy green PeLEDs are achieved with a maximum current efficiency of 54.35 cd A⁻¹ and a peak external quantum efficiency of 22.49%, representing the highest performance among green PeLEDs with partial lead substitution. Moreover, the T₅₀ lifetime of Zn-Lead alloy PeLEDs is ≈8.9 times longer than that of the pristine PeLEDs. The approach not only mitigates lead toxicity but also improves device efficiency and stability, representing a significant advancement toward safer and more sustainable perovskite-based optoelectronic devices.

End-to-end optimization of metalens and artificial intelligence-driven image restoration algorithms has recently emerged as a powerful tool for realizing ultra-compact imaging systems. However, the limited imaging quality of existing approaches remains challenging in meeting the demand for commercial devices due to the severe aberrations exhibited by metalens. These results in highly blurred sensor images, creating substantial challenges for accurate image restoration. In this work, a novel meta-imager is introduced that overcomes this challenge by employing an aperture-stop-integrated metalens and co-designing it with a computational image restoration network using a fully differentiable optimization framework. The proposed imager physically consists of a single metalens and an aperture stop located on the opposite side of the 1 mm-thick glass substrate. This configuration effectively alleviates off-axis aberrations such as coma and astigmatism, facilitating the image restoration process of the deep neural networks. The experimental results present that this scheme features 70° field-of-view, for full-color imaging across the entire visible spectrum. It is believed that this work represents a significant advancement in creating ultra-compact cameras using nanophotonics.

Developing matrix-free phosphorescent carbon dots (CDs) with tunable color emission and exceptionally long lifetimes is highly desirable for sophisticated information encryption. However, the majority of reported matrix-free CDs demonstrate only single-color emission and short lifetimes, restricting their practical applications. Herein, dual-emission self-protective room temperature phosphorescent CDs (DE-CDs) with ultra-long lifetimes and time-dependent afterglow colors are prepared. These DE-CDs are synthesized through a microwave heating process involving 1-butylamine and phosphoric acid aqueous solution. By adjusting excitation wavelength, they display green and yellow phosphorescence with ultra-long lifetimes of up to 1.25 and 1.74 s, respectively, representing the longest lifetime among matrix-free green and yellow CDs to date. The dual emission is attributed to the coexistence of a high-energy state within the carbon core and a low-energy state associated with C─N/C═N bonds on DE-CDs surface. The ultra-long lifetimes originate from the self-protective internal hydrogen bonds formed between P and N heteroatom-containing functional groups on the dot surface, which stabilize the emissive species. Intriguingly, under 365 nm irradiation, the afterglow color transitions from yellow to green due to differing triplet-state decay rates. Leveraging these time-dependent afterglow colors, a triple-code mode is achieved for advanced dynamic encryption.

Expanding the control of optomechanical coupling into the optical domain, namely beyond electronic and electromechanical gates, offers unequalled advantages in terms of spatial precision and remote operation. Here, a photochromic-based system is introduced with optically tunable optomechanical coupling. The system features a multilayered membrane as one of its mirrors, as well as a polymer layer doped with a photochromic molecule and a near-infrared absorbing dye. The interaction between mechanical modes and the electromagnetic field is harnessed to lower the effective temperature of mechanical vibrations. Laser cooling of a membrane vibrational mode is evidenced to about 115 K, and it is found that the cooling efficiency, mechanical damping, and photothermal response time can be effectively tuned by isomerization of the photochromic component. Such effect leads up to about 60% increase in cooling efficiency, related to photoinduced changes in volume and thermal properties during isomer conversion. These findings introduce new possibilities for the development of optomechanical systems with tunable properties entirely driven by light for applications in advanced sensing, nanomechanics, and optical logics.

Lead-free metal halide perovskites are emerging as less-toxic alternatives to their lead-based counterparts. However, their applicability in optoelectronic devices is limited, and the charge transport dynamics remain poorly understood. Understanding photo-induced charge and structural dynamics is critical for unlocking the potential of these novel systems. In this work, ultrafast optical and Raman spectroscopy combined with band structure calculations are employed to investigate the coupled electronic and vibrational dynamics in Caesium gold bromide, a promising lead-free perovskite. It is found that the band-edge charge transfer states are strongly coupled to Au─Br stretching phonon modes, leading to frequency modulation of absorption by coherent phonons. Early-stage relaxation is characterized by dynamics of delocalized charge transfer excitation and slowly decaying coherent phonons. The electronic and vibrational relaxation reveals a slow formation of a localized polaronic state in the 10–20 ps timescale. Using a displaced harmonic oscillator model, the polaronic binding energy is estimated to be ≈80 meV following lattice relaxation along the phonon modes. Strong exciton-phonon coupling and slow polaron formation via coupling to lattice modes make this material a promising testbed for the control of coherent phonons and localized polaronic states using light.

Although high-efficiency 9,10-bis[N,N-di-(p-tolyl)-amino]anthracene (TTPA)-based organic light-emitting diodes (OLEDs) are widely reported, their physical origins of excited states in TTPA are still vague. Herein, using the fingerprint magneto-electroluminescence probing tool, a resonant high-level reverse intersystem-crossing (HL-RISC, S_{1, TTPA} ← T_{2, TTPA}) of hot-excitons is discovered from the conventional fluorescent TTPA semiconductor whose triplet exciton states are generally ignored in the previous literature. This fascinating HL-RISC channel is well validated by the optical, electric, and magnetic properties of the undoped TTPA-based OLEDs. For TTPA-doped OLEDs, this channel can efficiently occur when triplet energies of the host and the exciton blocking layer are higher than that of T_{2, TTPA}. More importantly, an external quantum efficiency (EQE) as high as 10.14% is achieved from the simple emission layer without using any phosphorescent sensitizer, i.e., just by doping the TTPA emitter into the DMAC-DPS host with thermally activated delayed fluorescence property. This high EQE is attributed to fully harvesting singlet and triplet excitons of the device via the simultaneous utilization of the newly-found HL-RISC from TTPA guest and the low-level RISC from DMAC-DPS host. Accordingly, this work paves a novel pathway for designing high-performance fully fluorescent OLEDs with inherent device stability and low-cost superiority.

ReS₂ crystallizes in low crystal symmetry distorted triclinic (1T’) structure, and has anisotropic optical properties. Recently, two different stacking orders named as AA and AB phases, have been identified in ReS₂ with distinct characteristics, such as stacking order dependent Raman shift, carrier dynamics, and second harmonic generation (SHG). However, the low crystal symmetry structure combined with different stacking sequences complicate the understanding of optical responses of this material and thus instigating the debate on interlayer coupling, number of excitonic emissions, and quantum confinement. In this work, the open questions on the optical responses of ReS₂ are addressed by combining angle resolved photoluminescence (PL) at cryogenic temperatures and SHG spectroscopy on different numbers of layers of two polymorphs. Careful identification of stacking sequences allows to conclusively establish that few layer AA phase ReS₂ has two excitons, while AB phase demonstrates five emission peaks. SHG and PL imaging confirm layer parity dependent optical responses for AB phase ReS₂. Furthermore, bulk and few layer thick samples are found to have distinct PL, suggesting that bulk ReS₂ cannot be assumed as decoupled monolayers. The findings of this study hold significance toward understanding the optical phenomena occurring in polymorphs of anisotropic 2D layered materials.

Metal halide perovskites have attracted much attention due to their properties and wide applications in optoelectronic devices. B-site ion substitution, especially heterovalency substitution, is proven to be one of the practical approaches to modulate lattice structure and improve physicochemical properties. Here, lattice and bandgap modulation in all-inorganic perovskites CsPbX₃ are achieved by substituting Pb²⁺ with Bi³⁺. A series of CsPb_1-xBi_xBr₃ (0 ≤ x ≤ 1) microplates with the x values precisely tuned are prepared by a chemical vapor deposition (CVD) method. The lattice structure varies from single crystal CsPbBr₃ with a cubic structure to the single crystal Cs₃Bi₂Br₉ with a hexagonal structure. Correspondingly, three photoluminescence (PL) bands gradually emerge during the substituting: green, blue, and broad red-to-near-infrared emission. From micro-area photoluminescence spectra as a function of excitation power and temperature, combined with time-resolved PL characterization, the emission bands are confirmed from band-edge and self-trapped excitons (STEs) emission. From density functional theory (DFT) calculations, the STE emission in CsPb_0.9Bi_0.1Br₃ and CsPb_0.1Bi_0.9Br₃ is highly related to a combined defect contributed by bromide vacancy and the substitution of B-site ions. This study paves a new way for expanding the spectral range of perovskite emitters and even preparing white light-emitting devices.

The development of innovative dielectric materials is crucial for advancing metasurface optics. Chalcogenides are well-known for their unique optical properties and broadband high transmission from visible to infrared, which promises to be an emerging material platform for metasurface optics. However, the lack of chalcogenide materials in visible transmissive metasurfaces remains. In this work, the designs and experimental works of the first chalcogenide visible transmissive metasurface optics based on the chalcogenide material Ge₂₃Sb₇S₇₀ (GSS) platform are presented. Taking advantage of its high refractive index and low optical loss in visible, chalcogenide metalens, focused meta-vortex, meta-holographic devices, and computational visible spectrometers are designed and fabricated with a commendable performance. This work establishes the groundwork for realizing diverse functionalities and broader integration of chalcogenide metasurfaces at visible wavelengths.

Manganese-based halides present promising applications in flexible devices in versatile scenarios due to their low toxicity, high quantum yield, facile synthesis, and compatibility with multiple excitation sources. Herein, two novel manganese-based halides are synthesized, namely (CTP)₂MnCl₄ and (BTP)₂MnCl₄ (CTP = (2-chlorobenzyl)triphenylphosphonium, BTP = benzyltriphenylphosphonium), utilizing a solvent evaporation method. High photoluminescence quantum yields are achieved, ≈98.5% and 88.4%, respectively. Upon mechanical stimulations, both materials exhibited intense green emission attributed to the recombination of electrons and holes. Effective force-induced luminescence can be realized using a flexible, force-responsive film derived from the two compounds. In addition, the (CTP)₂MnCl₄ and (BTP)₂MnCl₄ crystals exhibited remarkable X-ray scintillation properties. Based on commercial CsI, Tl scintillator standards, the calculated light yields for (CTP)₂MnCl₄ and (BTP)₂MnCl₄ single crystals are ≈89 000 and 49 000 photons/MeV, respectively. A flexible scintillation film is fabricated with (CTP)₂MnCl₄ and polydimethylsiloxane. Furthermore, a light-emitting fiber film with a large area of 20 cm × 25 cm is fabricated using (CTP)₂MnCl₄ and polymethyl methacrylate via an electrospinning method. The film is suitable for applications in emergency rescue, information recording, and emergency lighting. This research provides a new approach for synthesizing large-sized, high-performance luminescence materials with multiple excitation sources and their versatile applications.