Advanced Optical Materials最新文献

Stretchable Metamaterials for Mechanochromic Color Shifting

In article number 2400921, Mark H. Griep, James J. Watkins, and co-workers report the fabrication of a strain-tunable, mechanochromic, color-shifting device by the combination of scalable nanoimprint lithography with layer-by-layer assembly. The integration of stretchable Bragg stack with gold and aluminum metasurfaces facilitates tunable structural colors and optical resonances from visible to near-infrared ranges. This stretchable device exhibits long-term stability, reversibility, and high spectral sensitivity to mechanical strain.

Photodetectors are a key sensing component in enabling emerging technologies. For weak light detection, phototransistors with high responsivity are needed. Furthermore, the ability to fabricate phototransistors using solution processing techniques will enable new form factors, including flexible and large-area devices. In this work, a novel approach for synthesizing a photosensitive organic/inorganic hybrid semiconducting thin film through solution processing is introduced. The approach involves hierarchical patterning of semiconducting carbon nanotubes (CNTs) with poly(3-hexylthiophene-2,5-dyl) (P3HT) through solution-phase heterogeneous crystallization. The fabricated hybrid phototransistors are qualified through electrical testing at varied illumination profiles within the visible light range. At a wavelength of 470 nm with an optical excitation power of 0.37 µW cm⁻², the device exhibits photoresponsivity of 3.53 × 10⁵ AW⁻¹, surpassing other solution-processed, non-lead-containing devices in the literature. The optical response extends from both photogating (low excitation power) and photon-induced carrier generation (high excitation power). The detectivity of the device is ≈8.7 × 10¹⁰ Jones. The transient response includes a rise time of 100 ms and a fall time of 200 ms which is similar to the metrics of other low-dimensional photodetectors. These findings highlight the prospects of the solution-processed P3HT/semi-CNT hybrid platform for advanced photodetection applications with flexible and large-area form factors.

Doping semiconductor nanomaterials with manganese ion (Mn²⁺) introduce a well-defined photoactive d-d level within the band structure, paving the way for diverse applications. Although Mn doping in single-layer 2D hybrid perovskites (n = 1) has been extensively studied, limited research has been conducted on doping with modulation of the layer thickness. Herein, Mn²⁺ doping in hybrid 2D perovskite nanoplatelets (NPLs), L₂A_n-1[Pb_1-xMn_x]_nBr_3n+1 (where L = butylammonium, A = methylammonium), with variations in Mn concentration (x = 0–0.60) and layer thickness (n = 1–3) is reported. Substitutional doping of Mn significantly increases the photoluminescence quantum yield as well as the rate of energy transfer efficiency, which strongly depends on the layer thickness of NPLs. The Mn concentration in 2D NPLs determines the rate of forward and backward energy transfer. Low-temperature emission spectra allow to determine thickness-dependent exciton binding energy for Mn-doped 2D NPLs (x = 0.5) with values of 410 ± 11 meV (n = 1), 188 ± 9 meV (n = 2), and 151 ± 17 meV (n = 3). The faster dissociation of band-edge excitons into free carriers at Mn²⁺ sites results in high brightness with an excellent CRI of 89.2 for the white light-emitting diode.

As an inorganic halide perovskite (IHP), CsPbI₂Br has generated enormous publicity due to its suitable optical bandgap (≈1.92 eV) and thermal stability. Unfortunately, the terrible phase stability of CsPbI₂Br film will cause a phase change in a wet environment and decelerate light response, seriously hindering the progression of IHP photovoltaics. Herein, a synergistic postmodification strategy with CsBr and MABr to achieve high-quality CsPbI₂Br film at a low-temperature (≈150 °C) and positive perovskite/carbon interface is presented. Adding a small amount of MABr can promote the crystallization of perovskite. The evaporated CsBr accumulates on the grain boundaries and surface of CsPbI₂Br and forms Br-rich perovskite, which provides the protection of CsPbI₂Br and segregation of water vapor. The carbon-based perovskite solar cell (C-PeSC) with the modified CsPbI₂Br harvests a high power conversion efficiency (PCE) of 11.04%. Notably, the unpackaged cell maintains 81% of its original PCE after being stored for 21 days in an air atmosphere with 25–35% humidity. Flexible devices are further manufactured, whose PCE drops to 90% of the initial value during 150 bending cycles. The flexible device also exhibits excellent blue photodetection performances. The maximum responsivity and detection reach 0.68 A W⁻¹ and 8.91 × 10¹² Jones, respectively. These findings provide broader avenues for flexible IHP in multifunctional devices.

A new type of material, organic salts in the crystal and crystalline powder state, with both excitation wavelength dependent (Ex-De) fluorescence and Ex-De phosphorescence under ambient conditions have been reported. The single component triphenylsulfonium chloride displays tunable fluorescent colors ranging from light purple to sky blue and tunable afterglow colors varying from green to yellowish green, to yellow (lifetimes: 57, 141, 66 ms, afterglow lasting for 2.1, 2.0, 2.3 s). The relationship between the structure and luminescence performance of 17 sulfonium salt derivatives confirms the pivotal roles of both the anions and the electronic and steric effect of substituent factors for luminescence. Single-crystal analysis reveals that unique ionic bonding and intermolecular interaction can promote an ordered arrangement of organic salts in a crystal state, which then can facilitate molecular aggregation for phosphorescence generation. Theoretical calculations have also confirmed this viewpoint. More importantly, these sulfonium salt derivatives can be used for advanced multimodal anti-counterfeiting and mitochondrial imaging, respectively. This study has not only expanded the scope of Ex-De materials but also extended their applications.

Communication between subcellular organelles is crucial for a synchronized cellular response which drives the search for chemical tools to simultaneously visualize dual organelles to unveil these dynamic interactions. A polarity-sensitive dual organelle targeting dioxaborine derivative, namely DOBEL, which stains lipid droplets (LDs) and endoplasmic reticulum (ER) simultaneously is introduced. This report is the first to demonstrate how the intrinsic difference in micropolarity drives the visualization of LDs in the green channel while ER in the red channel involves a single probe. The in situ emission spectra inside these organelles allow polarity quantification, further leading to deciphering the unique microenvironments in different cell lines. Exploiting ratiometric fluorescence imaging revealed how the micropolarity inside both LDs and ER alters during Ferroptosis. Altogether, DOBEL can be used as a superior imaging tool for monitoring LD-ER interaction during regular status and ferroptosis-related diseases in living cells.

Crystalline α-Gd₂(MoO₄)₃ is synthesized by sintering at 800 °C using a coprecipitation method to prepare the precursor. The resulting α-Gd₂(MoO₄)₃ displayed a monocrystalline structure with a strong main peak (-221) in the X-ray diffraction signal. To develop a light-emitting material, rare earth ions are added during synthesis. By doping with Tb³⁺ and Eu³⁺, the Gd₂(MoO₄)₃ down-conversion phosphor shows potential for use in UV–LED chips, counterfeit money prevention, and fingerprint identification. Additionally, co-doping with [Er³⁺]/[Yb³⁺] and [Ho³⁺]/[Yb³⁺] ions produce green and red emissions when applied to a 980 nm LED chip, useful for anti-counterfeit ink. The magnetic properties of gadolinium are leveraged to confirm magnetic resonance imaging luminescence. A flexible composite for heat detection and explored various applications for its use is also developed.

In biomedical and optical applications, multifunctional upconverting nanoparticles (UCNPs) play an essential role where non-invasive temperature sensing and imaging are necessary. UCNPs smaller than 20 nm, which can be excited under 808 nm wavelength, are particularly promising in this area and can be implemented in humans or other mammals. However, new versatile nanoprobes are still needed for biology, especially for challenging studies of small aquatic invertebrates. Such tools allow better monitoring and understanding of their physiology, biochemistry, and ecological responses, which is crucial due to the growing pollution of water reservoirs and climate change. Herein, multifunctional NaYF₄:Yb³⁺, Er³⁺@NaNdF₄:Yb³⁺ core@shell NPs (15 nm), forming stable aqueous colloids, exhibiting intense emissions under excitation in the first biological window (808 nm), and presenting high thermal sensitivity and resolution related to the thermally coupled energy levels of Er³⁺ ions, are designed and synthesized. Such properties of UCNPs are further utilized for optical imaging of aquatic invertebrates (Daphnia magna) and temperature detection inside their bodies under 808 nm excitation. This pioneering application of NaYF₄:Yb³⁺, Er³⁺@NaNdF₄:Yb³⁺ demonstrates the high potential of developed UCNPs for multifunctional applications, especially for bioimaging and temperature sensing within whole organisms.

An innovative elastic crystal based on barbituric acid derivatives (HBDT), which uniquely alters its fluorescence intensity under light exposure is developed. This crystal exhibits significant bending under 365 nm, 450 nm, white light, and sunlight while retaining its elasticity post-bending. The photomechanical effect of this crystal is driven by intermolecular [2+2] cycloaddition reactions, resulting in light-activated fluorescence enhancement. These properties open new avenues for applications in robotic arms, information identification, and optical waveguides, presenting a groundbreaking approach for sustainable and flexible crystal applications in material science and optical technology.

Iodine-based Sn-Pb mixed perovskite single crystals (SCs) are promising candidates for near-infrared (NIR) narrowband photodetectors due to their low bandgaps. However, they are highly defective when grown in ambient air due to the extremely poor air stability of Sn²⁺ ions in precursor solutions. It is discovered that the oxidation of Sn²⁺ to Sn⁴⁺ ions not only consumes Sn²⁺ ions but also increases the precursor solution viscosity. The increased viscosity slows down the solute diffusion and hinders the anisotropic growth of SCs, leading to Sn-Pb perovskite SCs with curved convex surfaces and unevenly distributed composition. By preventing the solute-diffusion-limited growth mode with hypophosphorous acid (H₃PO₂), high-quality Sn-Pb perovskite SCs can be robustly grown in ambient air with low trap density of 6.58 × 10⁹ cm⁻³ and high carrier mobility-lifetime product (µτ) of 1.5 × 10⁻³ cm² V⁻¹. Accordingly, a series of filterless NIR narrowband photodetectors with gradually tuned detection centers and dual detection modes has been achieved, delivering a maximum external quantum efficiency of 15.2% and detectivity of 1.19 × 10¹⁰ Jones.