Optical Stability Research Articles

One-Step Preparation of High-Stability CsPbX3/CsPb2X5 Composite Microplates with Tunable Emission.

The core-shell structure is an effective means to improve the stability and optoelectronic properties of cesium lead halide (CsPbX3 (X = Cl, Br, I)) perovskite quantum dots (QDs). However, confined by the ionic radius differences, developing a core-shell packaging strategy suitable for the entire CsPbX3 system remains a challenge. In this study, we introduce an optimized hot-injection method for the epitaxial growth of the CsPb2X5 substrate on CsPbX3 surfaces, achieved by precisely controlling the reaction time and the ratio of lead halide precursors. The synthesized CsPbX3/CsPb2X5 composite microplates exhibit an emission light spectrum that covers the entire visible range. Crystallographic analyses and density functional theory (DFT) calculations reveal a minimal lattice mismatch between the (002) plane of CsPb2X5 and the (10) plane of CsPbX3, facilitating the formation of high-quality type-I heterojunctions. Furthermore, introducing Cl- and I- significantly alters the surface energy of CsPb2X5's (110) plane, leading to an evolutionary morphological shift of grains from circular to square microplates. Benefiting from the passivation of CsPb2X5, the composites exhibit enhanced optical properties and stability. Subsequently, the white light-emitting diode prepared using the CsPbX3/CsPb2X5 composite microplates has a high luminescence efficiency of 136.76 lm/W and the PL intensity decays by only 3.6% after 24 h of continuous operation.

Synthesis of N-doped and P-doped silicon quantum dots and their applications for tetracycline detection in the honey samples and antibacterial properties

The abuse of tetracycline can lead to its residue in animal derived foods, posing many potential hazards to human health. Therefore, rapid and accurate detection of tetracycline is an important means to ensure food safety. Nitrogen doped and phosphorus doped silicon quantum dots (N-SiQDs, P-SiQDs) with remarkable optical stability were fabricated via a one-pot hydrothermal procedure in this study. Upon the excitation at 346 nm, N-SiQDs and P-SiQDs emitted fluorescence at 431 nm and 505 nm, respectively. Two SiQDs had the potential to serve as a probe for detecting low concentrations of tetracycline (TC), employing a mechanism of the static quenching effect. The calibration curves of N-SiQDs and P-SiQDs were linear within the range of 0–0.8 μM and 0–0.4 μM, the limits of detection were low as 5.35 × 10−4 μmol/L and 6.90 × 10−3 μmol/L, respectively. This method could be used successfully to detect TC in honey samples. Moreover, the remarkable antibacterial efficacy of two SiQDs could be attributed to the generation of a large number of intracellular reactive oxygen species. The SEM images showed that the structure of bacterial cell was disrupted and the surface became irregular when treated with both SiQDs. These properties enabled potential usage of SiQDs as excellent antibacterial material for different biomedical applications.

Improved Amplified Spontaneous Emission in Polycrystalline Perovskite Films by the Dual‐Site Synergistic Passivation Effects of ZnS

AbstractHalide perovskite materials are considered a promising optical gain medium for stimulated emission and have aroused tremendous interest in the field of laser research. The development of low‐threshold optically pumped amplified spontaneous emission (ASE) is critical for the advancement of continuous wave (CW) and electrically pumped micro‐nano lasers. In this work, an efficient ZnS additive is incorporated into the FA0.85MA0.15PbI2.55Br0.45 perovskite films to diminish the ASE threshold and extend the photostability by the dual‐site synergistic passivation. The experimental measurements and first‐principles calculations based on the density functional theory (DFT) are employed to elucidate the doping mechanism. The designed ZnS‐based perovskite films yield a mitigated ASE threshold of 8.5 µJ cm−2 with an elevated optical gain coefficient of 109.06 cm−1, which outperform those of the control films (12.7 µJ cm−2 and 74.10 cm−1). The in‐depth experimental characterizations and theoretical calculations have corroborated that the improvement of ASE performance can be ascribed to the dual‐site synergistic passivation effects of Zn2+ and S2−, which reduces the surface defects of perovskite films, suppresses the nonradiative charge recombination and improves the optical stability. This work provides a resultful strategy to construct the solution‐processed perovskite lasers with low thresholds and superior stability.

Water-Oil Interfacial Synthesis of Two-Dimensional Colloidal Lead-Iodide Perovskites with Enhanced Efficiency and Stability.

Two-dimensional Ruddlesden-Popper perovskites L2PbI4 (L = alkylammonium cation) (RPPs) have attracted significant attention due to their unique excitonic characteristics. However, their ultrafast reaction dynamics exacerbates the structural distortion of the inorganic framework, leading to severe deterioration in photoluminescence. Here, we propose a water-oil interfacial synthesis approach to achieve controlled growth of the RPPs nanosheets. By segregating Pb and I precursors in two immiscible solvents, the nucleation and growth of RPPs are prolonged to the minute level. L2PbI4 nanosheets terminated with various alkylammonium are synthesized, and the factors influencing the growth kinetics of RPPs nanosheets are investigated. The resulting (PEA)2PbI4 nanosheets exhibit a 3.6-time enhancement in quantum efficiency and 3.2-time improvement photostability compared to those synthesized using the classical recrystallization method. A white light-emitting diode based on (HDA)2PbI4 nanosheets is fabricated, achieving a color gamut of 119.7% of the NTSC display standards. This innovative approach offers a new method for the controlled growth of 2D RPPs with improved optical quality and stability.

Cryogenic Thermal Shock Effects on Optical Properties of Quantum Emitters in Hexagonal Boron Nitride.

Solid-state quantum emitters are vital building blocks for quantum information science and quantum technology. Among various types of solid-state emitters discovered to date, color centers in hexagonal boron nitride have garnered tremendous traction in recent years, thanks to their environmental robustness, high brightness, and room-temperature operation. Most recently, these quantum emitters have been employed for satellite-based quantum key distribution. One of the most important requirements to qualify these emitters for space-based applications is their optical stability against cryogenic thermal shock. Such an understanding has, however, remained elusive to date. Here, we report on the effects caused by such thermal shock that induces random, irreversible changes in the spectral characteristics of the quantum emitters. By employing a combination of structural characterizations and density functional calculations, we attribute the observed changes to lattice strain caused by cryogenic temperature shock. Our study sheds light on the stability of the quantum emitters under extreme conditions─similar to those countered in outer space.

Fluorination effects on bithiophene bridged hole transporting materials for perovskite solar cells

ABSTRACT The use of hole transporting material (HTM) remains indispensable for efficient charge extraction in perovskite solar cells. In this work, a series of small-molecule HTMs are designed by introducing fluorine atoms into the central part of 2,2′-bithiophene core. The effect of fluorination on the photophysical, electrochemical, and hole transport properties is systematically explored using Quantum chemistry calculation. The Calculated results reveal that all the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) of the studied molecules are well matched with the energy band structure of perovskite. Three fluorine substituted hole-transporting materials possess lower reorganisation energy than the reference molecule BT-MTP. The higher mobility and matched energy levels of predicted HTMs are beneficial for improving the performance of PSCs. All the designed HTMs display higher hole mobility than those of the BT-MTP. Especially, molecule DFBT-p-MTP exhibits better optical properties and stability, indicating that fluorination is an effective strategy to improve the performance of the device in real application. This work provides an avenue for designing low-cost small molecule HTMs for high-performance perovskite solar cells.

Fabricating S-scheme Sb2S3@CdSexS1–x quasi-one-dimensional heterojunction photoanodes by in-situ growth strategy towards photoelectrochemical water splitting

Nowadays, energy and environmental problems are becoming increasingly prominent in society, the development of clean and environmentally friendly energy is in line with the construction of ecological civilization and energy, which have attracted the attention of many researchers over the past decades. Narrow band gap semiconductor Sb2S3 is widely used in the area of solar cells because of its high light absorption coefficient and suitable bandgap width. However, numerous deep-level defects provide plentiful photogenerated carrier recombination sites, which restricts the improvement of photoelectrochemical properties seriously. In this work, S-scheme Sb2S3@CdSexS1–x core-shell quasi-one-dimensional heterojunction photoanodes were prepared on the FTO substrate by a two-step vapor transport deposition (VTD) method, chemical bath deposition (CBD) and in-situ selenization method. The results showed that CdSexS1–x nanoparticles (NPs) were tightly coated on the Sb2S3 nanorods (NRs). The photocurrent density of the Sb2S3@CdSexS1–x photoanodes was 1.61 mA cm–2 under 1.23 VRHE. Compared with the Sb2S3 photoanodes (0.61 mA cm–2), Sb2S3@CdSexS1–x photoanodes obtained a 2.64-fold improvement, and the dark current was effectively reduced. It showed excellent stability and fast photocurrent response in a 600 s optical stability test. It was concluded that: (1) The charge transfer mechanism of the S-scheme can avoid the problem of high recombination rate of photogenerated charge carriers due to the defects of Sb2S3 effectively, and realized spatial separation of photogenerated carriers. (2) The [hk1] oriented Sb2S3 NRs and the formed quasi-one-dimensional heterostructures promote efficient carrier transport. (3) The introduction of Se effectively regulated the band structure of CdS, slowed down the photocorrosion of S, and improved the stability of the photoelectrodes significantly.

Comparison of Optical Properties and Radiation Stability of Gd2O3 Micro- and Nanopowders

Comparison of Optical Properties and Radiation Stability of Gd2O3 Micro- and Nanopowders

Discovery of Near-Infrared Heptamethine Cyanine Probes for Imaging-Guided Surgery in Solid Tumors.

Near-infrared (NIR) fluorescence imaging has attracted much attention in image-guided interventions with unique advantages. However, the clinical translation rate of fluorescence probes is extremely low, primarily due to weak lesion signal contrast and poor specificity. To address this dilemma, a series of small-molecule near-infrared fluorescence probes have been designed for tumor imaging. Among them, YQ-04-03 showed notable optical stability and remarkable sensitivity toward tumor targeting. Moreover, within a specific concentration and time range against oxidizing reducing agents and laser, it demonstrated better stability than ICG. The retention time of YQ-04-03 in tumors was significantly longer compared to other nonspecific uptake sites in the subjects, and its tumor-to-normal tissue ratio (TNR) outperformed ICG. Successful resection of in situ hepatocarcinoma and peritoneal carcinoma was achieved using probe imaging guidance, with the smallest visual lesion resected measuring approximately 1 mm3. Ultimately, this probe holds great potential for advancing tumor tracer.

Smart Energy Storage: W18O49 NW/Ti3C2Tx Composite-Enabled All Solid State Flexible Electrochromic Supercapacitors.

Developing a highly efficient electrochromic energy storage device with sufficient color fluctuation and significant electrochemical performance is highly desirable for practical energy-saving applications. Here, to achieve a highly stable material with a large electrochemical storage capacity, a W18O49 NW/Ti3C2Tx composite has been fabricated and deposited on a pre-assembled Ag and W18O49 NW conductive network by Langmuir-Blodgett technique. The resulting hybrid electrode composed of 15 layers of W18O49 NW/Ti3C2Tx composite exhibits an areal capacitance of 125mFcm-2, with a fast and reversible switching response. An optical modulation of 98.2% can be maintained at a current density of 5mAcm-2. Using this electrode, a bifunctional symmetric electrochromic supercapacitor device having an energy density of 10.26µWhcm-2 and a power density of 0.605mWcm-2 is fabricated, with high capacity retention and full columbic efficiency over 4000 charge-discharge cycles. Meanwhile, the device displays remarkable electrochromic characteristics, including fast switching time (5s for coloring and 7s for bleaching), and a significant coloration efficiency of 116cm2C-1 with good optical modulation stability. In addition, the device exhibits significant mechanical flexibility and fast switching while being stable over 100 bending cycles, which is promising for real-world applications.

Development of a hydrogel containing bisabolol-loaded nanocapsules for the treatment of atopic dermatitis in a Balb/c mice model

α-Bisabolol (αBIS), a plant-derived compound with anti-inflammatory properties, is potentially a therapeutic agent for Atopic dermatitis. However, its poor water solubility and photoinstability limit its topical application. Therefore, the present study, aimed to develop cationic polymeric nanocapsules of αBIS to improve its skin delivery, photostability, and therapeutic efficacy. The αBIS-loaded nanocapsules were prepared using the solvent displacement technique. A Box-Behnken (BB) design was employed to statistically optimize formulation variables and αBIS-loaded nanocapsules characterized by particle size, surface charge and encapsulation efficiency. The optimal formulation was selected, and the spherical shape of the nanocapsules was confirmed by scanning electron microscopy (SEM). Furthermore, hydrogel containing αBIS-loaded nanocapsules was prepared by thickening of nanocapsule suspension with Carbopol 934 and evaluated for rheology, in vitro drug release and skin permeation. Furthermore, a mice model of atopic dermatitis was used to evaluate the anti-inflammatory potential of the hydrogels. The optimal formulation displayed a spherical morphology under scanning electron microscopy (SEM) with an optimum particle size of 133.00 nm, polydispersity index (PDI) of 0.12, high EE% of 93 %, and improved optical stability of αBIS in the prepared nanocapsules compared to the free drug. The nano-based hydrogels demonstrated non-Newtonian pseudoplastic behavior and an increased αBIS in vitro release profile without causing skin irritation in rabbits. Drug retention within the dermis and epidermis layers significantly surpassed that of drug-free hydrogel. Moreover, in vivo histopathological studies and myeloperoxidase (MPO) enzyme activity, revealed that hydrogel containing bisabolol nanocapsules exhibited The best anti-inflammatory effect. The results showed that hydrogels containing bisabolol nanocapsules markedly alleviated dermatitis-related inflammation and reduced skin thickness in Balb/c mice. Our findings support nanocapsules as an effective drug delivery system to enhance αBIS stability, bioavailability, and therapeutic efficacy in AD treatment.

Graphene quantum dots enhance the biological nitrogen fixation by up-regulation of cellular metabolism and electron transport

Graphene quantum dots (GQDs) are useful nanomaterials of excellent water solubility, biocompatibility and optical stability for various applications. In this study, we achieved the nitrogen fixation activity enhancement of autogenous azotobacters (Azotobacter vinelandii) by GQDs and revealed its mechanism. GQDs (1–10 mg/L) accelerated the logarithmic growth phase of A. vinelandii, making bacteria enter the plateau earlier. Biocompatible GQDs did not cause cell death and oxidative damage of A. vinelandii. The expression levels of metabolism and nitrogen fixation related genes were significantly up-regulated by GQDs, thereby enhancing the activity of nitrogenase. The nitrogen fixation activity of A. vinelandii reached 471.7 % of the control upon the exposure to GQDs. The intracellular polyhydroxyalkanoate vesicles were consumed to provide energy for nitrogen fixation, which involved with a chain reaction of carbohydrate metabolism, lipid metabolism, and energy metabolism pathways accompanied by significant increases in electron transfer rate. The synergistic effect of GQDs on A. vinelandii further facilitated the augmentation of soil nitrogen content in Qinghai-Tibet Plateau. Our results provided an effective approach to enhance the biological nitrogen fixation by GQDs.

A Molecularly Imprinted Fluorescence Sensor Based on Upconversion-Nanoparticle-Grafted Covalent Organic Frameworks for Specific Detection of Methimazole

Rapid detection and sensitive analysis of MMZ is of great importance for food safety. Herein, a fluorescent molecularly imprinted sensor based on upconversion nanoparticles (UCNPs) grafted onto covalent organic frameworks (COFs) was designed for the detection of MMZ. COFs with a high specific surface area and excellent affinity serve as substrates for grafting of UCNPs, which can inhibit the aggregation burst of UCNPs and improve the mass transfer rate of the sensor. Through a series of characterizations, it was found that the proposed UCNP-grafted COFs@MIP-based sensor had good optical stability, high adsorption efficiency, strong anti-interference ability, and high sensitivity owing to the integration of the advantages of UCNPs, COFs and MIPs. Under the optimal conditions, a good linear relationship was presented between the fluorescence intensity of UCNP-grafted COFs@MIPs and the methimazole concentration in the range of 0.05–3 mg L−1, and the detection limit was 3 μg L−1. The as-prepared UCNP-grafted COFs@MIPs were successfully applied for the detection of MMZ in actual samples, and the results were relevant with those determined by high-performance liquid chromatography. The sensor has good sensitivity, reusability, and high selectivity, which are highly valuable in the rapid analysis and detection of food safety.

One-pot Synthesis of High-performance Green-emitting Carbon Dots for Cd2+ Sensing and Anti-counterfeiting Applications.

This study presents a facile one-pot solvothermal synthesis of high-performance green fluorescent carbon dots (G-CDs) using o-phenylenediamine and ethylenediamine as precursors. The G-CDs show excellent optical, temporal, and chemical stability. Notably, they exhibit the highest quantum yield of 24.2% in ethanol and a strong green emission peaking at 546nm under 440-490nm excitation. In addition, G-CDs have outstanding salt resistance and multi-solvent compatibility. Due to its bright photoluminescence, G-CDs can be used as a secure ink for anti-counterfeiting. More remarkably, Cd2+ ions can efficiently quench the fluorescence of G-CDs with a detection limit of 0.152 µmol/L, enabling accurate quantification of Cd2+ in water systems. The simple synthesis of high-performance G-CDs expands their applicability in sensing and bioimaging.

Shielding parameters and optical stability of sodium alumino-borate glasses against gamma rays by iron oxide additives

The development of various industries and technologies necessitates a greater utilization of ionizing radiation, such as gamma rays. Herein, we investigate the shielding parameters and the stability of the optical parameters of sodium alumino-borate glasses against gamma rays by different iron oxide (Fe2O3) additives. We found that the Fe2O3 additives improved the shielding parameters. Moreover, the influence of various doses of γ rays (50, 100, and 150 kGy) on the optical characteristics of the performed glasses was studied. For example, the influence of gamma doses on the optical absorbance (A), optical band gap (Eg), Urbach energy (EU), refractive index (no), electronegativity (X), electron polarizability (αo), and nonlinear refractive index (n2). The optical absorbance of all glass samples increased, particularly in the visible range, with further irradiation.Furthermore, the reduced optical band gap and Urbach energy values grow as the gamma irradiation increases, which are attributed to the increased number of donor centres. Conversely, an investigation was conducted on the ability of the material to protect against radiation. We found that the Fe2O3 additives improved the shielding parameters. Furthermore, the half-value layer results of the glassy samples in question were compared to those of conventional radiation shielding materials and glasses. Therefore, the glass samples work better at blocking radiation than conventional window glass when employed for radiation shielding purposes.

Optical solitons and stability analysis for NLSE with nonlocal nonlinearity, nonlinear chromatic dispersion and Kudryashov’s generalized quintuple-power nonlinearity

In this paper, we consider the nonlinear Schrödinger equation (NLSE) with nonlocal nonlinearity having nonlinear chromatic dispersion and Kudryashov’s generalized quintuple-power. For the suggested model, dark solitons, and singular solitons are investigated using the modified extended mapping approach. Furthermore, rational solutions, exponential solutions, hyperbolic wave solutions, singular periodic solutions, and Jacobi elliptic function solutions are shown. We impose certain limits on the parameters in order to guarantee the existence of the obtained soliton solutions. Furthermore, a few chosen solutions are also displayed graphically to illustrate the physical characteristics of the precise solutions. Furthermore, we use the idea of modulation instability analysis to discuss the stability of the derived wave solutions.

Hydrogen‐Bonded Organic Frameworks Enabling Highly Robust Aqueous Phase Ultralong Room‐Temperature Phosphorescence

AbstractAqueous phase room‐temperature phosphorescence (RTP) materials are attracting increasing interest owing to their unique optical properties and promising applications. However, the realization of ultralong aqueous state RTP remains a formidable challenge due to severe quenching of triplet excitons in aqueous medium. In this study, a universal strategy is presented to achieve aqueous RTP materials through the encapsulation of organic phosphors within rigid hydrogen‐bonded organic frameworks (HOFs) by in situ self‐assembly. Benefiting from the compact and rigid microenvironments provided by HOFs, the nonradiative dissipations are immensely suppressed and populated triplet excitons are greatly stabilized by geometrical confinement and isolating organic phosphors from quenchers. As a result, the assembled HOFs‐based materials reveal robust RTP emission with an ultralong phosphorescence lifetime of up to 493.1 ms and exhibit long‐term optical and structural stability in water and even in harsh conditions (acid and base) for more than 10 days. Moreover, a fluorescent dye is introduced to finely tune the afterglow performance based on triplet‐to‐singlet Förster resonance energy transfer (TS‐FRET), facilitating advanced information encryption and anticounterfeiting applications. This study provides a reliable and universal method to design and prepare robust RTP materials and expands their applications in advanced information encryption.

A strategy for the enhanced development of latent fingermarks with minimally destructive to DNA based on fluorescence Eu-Tb metal–organic framework

Fingermarks identification have always been the most effective and reliable way for individuals determination among the forensic science. The fingermarks at the scene of the case as the valuable physical evidence to analyze the trajectory of criminal behavior and portray the characteristics of the suspect play an irreplaceable role in the process of investigation. To reach its pivotal biometric individualization, the luminescent metal–organic framework (Eu@Tb-LL) was prepared via a simple optimized solvothermal method for visualizing the latent fingermarks with minimally destructive to DNA in this work. Eu@Tb-LL exhibited ideal optical stability and fluorescence intensity at the wavelength of 530 and 620 nm during revealing latent fingermarks. Meanwhile, Eu@Tb-LL is more effective than indandione (commonly used in the site investigation) in revealing aged fingermarks. More significantly, the Eu@Tb-LL superimposed on commercial manifestation reagents (Hfb) enhanced the effect of Hfb for revealing blood latent fingermarks on the non-porous objects. In addition, the STR testing results performed after the visualization process proved the Eu@Tb-LL was minimally destructive to DNA with a confidence interval of 95 %, exhibiting promising prospects for practical criminal investigation applications.

Enhanced Amplified Spontaneous Emission from Perovskite Films by a Multifunctional 4′‐Aminoacetophenone Hydrochloride Additive Assistant Engineering

AbstractMetal halide perovskites are considered as a prospective candidate as optical gain media for stimulated emission, and the advancement of amplified spontaneous emission (ASE) of perovskite materials is gradually becoming the key to realize the commercialization of perovskite lasers. Nonetheless, the ASE of solution‐processed polycrystalline perovskite films still experiences a high threshold and poor optical stability due to their high defect density and poor crystalline quality. In this scenario, a noticeably ameliorated ASE performance with decreased threshold and greater photo‐stability is demonstrated in solution‐processed (FAPbI3)0.85(MAPbBr3)0.15 polycrystalline perovskite films by introducing a neoteric 4′‐Aminoacetophenone hydrochloride (APCl) additive with cost‐effective fabrication. The ASE threshold of the APCl‐embedded perovskite films is prominently curtailed from 12.8 to 5.3 µJ cm−2, with an augmented optical gain, ASE output intensity, and optical durability. The ameliorated ASE performance can be credited to multifunctional effects of the APCl additive in the perovskite films, presenting a low defect density, an unambiguously elevated photoluminescence, a prolonged decay lifetime and thus enabling the easily achieved population inversion caused by the attenuated nonradiative carrier recombination in the optical gain media. These findings provide a significant foundation and pave the way for realizing the electrically excited lasing based on the perovskite materials.

First-principles screening of metal–organic frameworks for entangled photon pair generation

The transmission of strong laser light in nonlinear optical materials can generate output photons sources that carry quantum entanglement in multiple degrees of freedom, making this process a fundamentally important tool in optical quantum technology. However, the availability of efficient optical crystals for entangled light generation is severely limited in terms of diversity, thus reducing the prospects for the implementation of next-generation protocols in quantum sensing, communication and computing. To overcome this, we developed and implemented a multi-scale first-principles modeling technique for the computational discovery of novel nonlinear optical devices based on metal–organic framework (MOF) materials that can efficiently generate entangled light via spontaneous parametric down-conversion (SPDC). Using collinear degenerate type-I SPDC as a case study, we computationally screen a database of 114 373 synthesized MOF materials to establish correlations between the structure and chemical composition of MOFs with the brightness and coherence properties of entangled photon pairs. We identify a subset of 49 non-centrosymmetric mono-ligand MOF crystals with high chemical and optical stability that produce entangled photon pairs with intrinsic G(2) correlation times τc∼10−30 fs and pair generation rates in the range 104−1010s−1mW−1mm−1 at 1064 nm. Conditions for optimal type-I phase matching are given for each MOF and relationships between pair brightness, crystal band gap and optical birefringence are discussed. Correlations between the optical properties of crystals and their constituent molecular ligands are also given. Our work paves the way for the computational design of MOF-based devices for optical quantum technology.