Ultrahigh Quantum Yield Research Articles

Organic NIR‐II Nanofluorophore with Ultrahigh Quantum Yield for Vessels Imaging and Fluorescence Image‐Guided Surgery

Organic NIR‐II Nanofluorophore with Ultrahigh Quantum Yield for Vessels Imaging and Fluorescence Image‐Guided Surgery

The highly efficient and stable near-infrared phosphor Ca3MgSnGe3O12: Cr3+ for multifunctional application

The investigation of efficient and stable near-infrared (NIR) luminescent materials is crucial for rapidly developing near-infrared spectroscopic techniques. Herein, NIR phosphors Ca3MgSnGe3O12: Cr3+ with ultra thermal stability and high internal quantum yield (IQY) are explored. The emission intensity remained at 91.75 %@423 K of room temperature and the IQY/EQE reaches 91.41 %/34.04 % after doping the H3BO3 flux agent for optimization. Moreover, a single luminescence center was identified by cryogenic photo luminescence spectroscopy (PL) from 4 K to 300 K and lifetime decay curve. Importantly, NIR light can easily removes all kinds of background interference that cannot be easily eliminated by visible light, which is not only widely used in night vision and biological tissue penetration, but also has higher application prospects in NIR fingerprint detection. Moreover, it clearly displays high level of fingerprint details under high temperature conditions and after water immersion, thus it is perfectly suited for using in Automatic Fingerprint Identification System (AFIS) systems. Therefore, Ca3MgSnGe3O12: Cr3+ NIR pc-LEDs have great potential for latent fingerprint detection at actual crime scenes.

Phosphonium Iodide Featuring Blue Thermally Activated Delayed Fluorescence for Highly Efficient X-Ray Scintillator.

Organic scintillators are praised for their abundant element reserves, facile preparation procedures, and rich structures. However, the weak X-ray attenuation ability and low exciton utilization efficiency result in unsatisfactory scintillation performance. Herein, a new family of highly efficient organic phosphonium halide salts with thermally activated delayed fluorescence (TADF) are designed by innovatively adopting quaternary phosphonium as the electron acceptor, while dimethylamine group and halide anions (I-) serve as the electron donor. The prepared butyl(2-[2-(dimethylamino)phenyl]phenyl)diphenylphosphonium iodide (C4-I) exhibits bright blue emission and an ultra-high photoluminescence quantum yield (PLQY) of 100 %. Efficient charge transfer is realized through the unique n-π and anion-π stacking in solid-state C4-I. Photophysical studies of C4-I suggest that the incorporation of I accounts for high intersystem crossing rate (kISC) and reverse intersystem crossing rate (kRISC), suppressing the intrinsic prompt fluorescence and enabling near-pure TADF emission at room temperature. Benefitting from the large Stokes shift, high PLQY, efficient exciton utilization, and remarkable X-ray attenuation ability endowed by I, C4-I delivers an outstanding light yield of 80721 photons/MeV and a low limit of detection (LoD) of 22.79 nGy ⋅ s-1. This work would provide a rational design concept and open up an appealing road for developing efficient organic scintillators with tunable emission, strong X-ray attenuation ability, and excellent scintillator performance.

Carbon quantum dots with ultra-high quantum yield for versatile turn-on sensor of gluten and cyanide Ions

In this work, we reported the synthesis of carbon quantum dots (CQDs) with high fluorescent quantum yield (90.7 %). These nanoparticles were applied in a turn-off/turn-on sensor able to detect cyanide ions. In this sensing strategy, Fe3+ ions were added to the aqueous suspension of CQDs to quench the fluorescence of the system, which was recovered from the presence of cyanide ions. Furthermore, a sensor array was developed using the LDA chemometric tool, to classify different species present in cookie formulations, including gluten. The turn-off/turn-on sensor proved to be sensitive and effective for detecting cyanide ions, with a detection limit of 3.77 ppm. This high sensibility and selectivity allowed quantifying the analyte in a real sample of tap water.

Molecular engineering design of twisted-backbone pure Type-I organic photosensitizers for hypoxic photodynamic therapy

Photodynamic therapy (PDT), an emerging tumor therapeutic strategy has received tremendous attention. Enslaved by the high dependence of oxygen, Type-II photosensitizers (PSs) mediated PDT is restricted by the hypoxic environment of tumors. By transferring electrons to water or other substrates instead of oxygen, Type-I PSs hold the promise of achieving an ideal therapeutic effect under hypoxic conditions. In this study, three twisted-backbone PSs (CBz-TQs-1, CBz-TQs-2 and CBz-TQs-3) are synthesized and studied. Owing to different substituent effects, the ROS generation mechanism transfers from pure Type-II of their prototype PSs (TQs-1, TQs-2 and TQs-3) to mixed Type-I/II of CBz-TQs-1 and CBz-TQs-2 to pure Type-I of CBz-TQs-3. Moreover, CBz-TQs-3 exhibits an ultra-high ROS quantum yield (∼1.0). The in vitro and in vivo PDT effects of water-dissolvable nanoparticles (NPs) of CBz-TQs-3 are investigated. The results show that the phototoxicity of CBz-TQs-3 is not affected by hypoxic environments. In addition, a remarkable tumor ablation can be found after CBz-TQs-3 NPs mediated PDT on Balb/c mice with xenograft tumors. It proves that a twisted backbone strategy is beneficial for designing pure Type-I PSs with high-efficient hypoxic PDT.

Ultrabright Xanthene Fluorescence Probe for Mitochondrial Super-Resolution Imaging.

Mitochondria are important organelles that provide energy for cellular physiological activities. Changes in their structures may indicate the occurrence of diseases, and the super-resolution imaging of mitochondria is of great significance. However, developing fluorescent probes for mitochondrial super-resolution visualization still remains challenging due to insufficient fluorescence brightness and poor stability. Herein, we rationally synthesized an ultrabright xanthene fluorescence probe Me-hNR for mitochondria-specific super-resolution imaging using structured illumination microscopy (SIM). The rigid structure of Me-hNR provided its ultrahigh fluorescence quantum yield of up to 0.92 and ultrahigh brightness of up to 16,000. Occupying the para-position of the O atom in the xanthene skeleton by utilizing the smallest methyl group ensured its excellent stability. The study of the photophysical process indicated that Me-hNR mainly emitted fluorescence via radiative decay, and nonradiative decay and inter-system crossing were rare due to the slow nonradiative decay rate and large energy gap (ΔEst = 0.55 eV). Owing to these excellent merits, Me-hNR can specifically light up mitochondria at ultralow concentrations down to 5 nM. The unprecedented spatial resolution for mitochondria with an fwhm of 174 nm was also achieved. Therefore, this ultrabright xanthene fluorescence probe has great potential in visualizing the structural changes of mitochondria and revealing the pathogenesis of related diseases using SIM.

In situ Surface Reconstruction in Pure Water by Ice‐Confined Freeze‐Thaw Strategy for High‐Performance Core–Shell Structural Perovskite Nanocrystals

AbstractConstructing core–shell structure is recognized as an effective approach for the conventional colloidal semiconductor nanocrystals (NCs) to improve their stability and optical performance in optoelectronic applications. It is, however, still a challenge to develop green manufacture for core–shell lead halide perovskite NCs (PeNCs). Herein, an ice‐confined freeze‐thaw strategy using pure water solvent is devised, which results in the surface reconstruction of CsPbBr3 PeNCs thereby formatting the CsPb2Br5 shell on the CsPbBr3 core to achieve core–shell CsPbBr3@CsPb2Br5. The in situ formation of the CsPb2Br5 shell is attributed to the transformation of the intermediate polyhedral structure with the help of amphiphilic 4‐dodecylbenzene sulfonic acid ligand in the precursor solution. The PeNCs show ultrahigh photoluminescence quantum yield of 95%, remarkable stability and humidity‐resistance. Moreover, both light‐emitting diodes and stretchable fluorescence hydrogels based on the PeNCs exhibit a boosted optical performance and excellent operation stability. The organic solvent‐free and recyclability of this strategy pave a novel way to the environmentally friendly and large‐scale manufacture of high‐quality PeNCs for optoelectronic application.

Development of thermally stable red-emitting lead-free double-perovskite phosphors with an internal PLQY approaching 100.

White light-emitting diode (WLEDs), acting as a new generation of solid-state lighting, play a critical role in energy conservation. Red-emitting phosphors with high efficiency could effectively improve the quality of WLED devices. In this report, Eu3+-doped Ca2ScTaO6 luminescent materials have been successfully synthesized by a high-temperature solid-state method. Its crystal structure was confirmed to be a monoclinic lead-free double-perovskite material system with the space group P21/n by the X-ray diffraction patterns. The strongest emission peak was about 614 nm distributed to the 5D0 → 7F2 electric-dipole transition. Additionally, the optimal doping concentration was found to be 40 mol%, and the concentration quenching mechanism is assigned to d-d interactions. The Ca2ScTaO6:Eu3+ phosphors exhibited an ultrahigh internal quantum yield (about 100%) with good thermal stability (81.5% at 423 K compared with the emission intensity at 303 K). Furthermore, a WLED with a suitable correlated color temperature (4201 K) and a color rendering index (87.62) was fabricated. The phosphor-based polydimethylsiloxane light-emitting flexible film exhibited good luminescence, which is suitable to be utilized in flexible displays. The obtained results suggest that the high-efficiency red-emitting Ca2ScTaO6:Eu3+ phosphors are promising commercial candidates for use in near-ultraviolet-excited WLEDs.

A turn-on fluorescence molecularly imprinted sensor based on covalent organic framework for specific and visual detection of α-dicarbonyl compounds

In this paper, a turn-on fluorescence sensor (COFTPDD@ILMIPs) was prepared for the detection and removal of the α–dicarbonyl compound 3-deoxyglucosone (3-DG) in milk. The sensor uses ultra-high quantum yield green fluorescent covalent organic frameworks (COFs) as the fluorescence center, and introduces ionic liquids to improve its fluorescence performance and mass transfer rate, and the selectivity and anti-interference ability of the sensor were improved by molecular imprinted technique. In addition, the sensor was combined with a smartphone sensing platform to achieve real-time quantitative detection of 3-DG in the field. The quantitative detection of 3-DG in a good linear range (0.5–100 μg/L) was observed, and the low limit of detection was 0.31 μg/L. The spiked recoveries of 3-DG in milk samples ranged from 81.96–117.39 %, which provided an effective strategy for the accurate and rapid detection of hazardous substances in milk.

Rapid synthesis of ultra-bright blue and cyan CQDs fluorescent powders based on chemical dispersion and concentration effects

It is often impossible to obtain solid carbon quantum dots (CQDs) fluorescent powder by direct drying due to a self-quenching effect, which limits their large-scale application. Here, we first report a general method for rapidly conversing CQDs solution into fluorescent powder via a crosslinking reaction of 3-glycidyloxypropyltrimethoxysilane (KH-560). Initially, N-doped CQDs (N-CQDs) with an ultra-high quantum yield (QY) of 98.45 % and concentration-dependent luminescence behavior were synthesized via a straightforward hydrothermal reaction involving citric acid and ethylenediamine. The N-CQDs solution at low and high concentrations emits blue and cyan fluorescence under ultraviolet light, respectively. By the action of aqueous ammonia, KH-560 quickly forms a gel matrix at room temperature to realize the dispersion and anchor of N-CQDs to prepare N-CQDs fluorescent powder (NK). NK not only inherits the strong luminescence performance (QY = 71.87 %) of N-CQDs but also exhibits excellent fluorescence stability, successfully applied in blue and cyan LED lighting and fluorescent ink.

Highly sensitive metal-enhanced fluorescence platform based on high-quality CdSe/ZnS quantum dots and gold nanodendrites

Fluorescence immunosensors are highly demanded for diagnosing, monitoring and pathogenesis of diseases. Yet, the low sensitivity due to the weak fluorescence intensity of commonly employed fluorescent materials is the major obstacle towards early accurate diagnosis of targeted diseases. Herein, we resolve this issue by designing a highly sensitive fluorescence platform via employing colloidal quantum dots (QDs)-metal nanoparticles hybrid system. The QDs exhibit high chemical, thermal, and optical stability, excellent biocompatibility with ultrahigh quantum yield (∼88 %). They exhibit a core/shell architecture with type-I band alignment. The gold nanodendrites (AuNDs) synthesized via seed growth method with controllable sizes exhibit anisotropic shape, which maximizes the impacts of local surface plasmon resonance to amplify the fluorescence performance of colloidal QDs. Utilizing the designed platform and taking C-reactive protein as a testcase, we achieve ∼17-fold sensitivity improvement compared with metal nanoparticles free sensing platform, and a wide detection range between 0.25 ng/mL and 1000 ng/mL, and a low detection limit of 0.056 ng/mL. The designed sensing platform has been extended for the detection of real blood and tissue samples, and competing results have been delivered compared with the prevailing detecting technique. The present work reports a novel route of designing biological sensing platform through fluorescence amplification, which holds great potential for highly sensitive and throughput detection in clinical applications, and is widely applicable for highly sensitive detection of other biomarkers in biomedical applications.

Rational Design of Dual‐Mode Emitting Carbon Dots to Exploit the Synergistic Effect of Matrices for High‐Efficiency WLEDs and Anti‐Counterfeiting

AbstractLong‐lived room‐temperature phosphorescence (RTP) materials have been widely applied in various fields. However, achieving high‐performance carbon dots (CDs) RTP remains a great challenge. Here, a facile synthetic strategy is rationally designed for the synthesis of high‐performance dual‐mode emitting CDs by constructing rigid structures through the synergistic effect of the matrices. The obtained CD RTP powder possesses an ultrahigh photoluminescence quantum yield (PLQY) of 70.7%, a phosphorescence lifetime of about 0.45 s, and an afterglow that lasts for 15 s to the naked eyes. Most importantly, the prepared CD RTP powder can be utilized as a commercial phosphor powder for the fabrication of a high‐performance white lighting‐emitting diode (WLED) with a CIE coordinate of (0.39, 0.39), a high color rendering index of 93.6, and a color temperature of 3805 K for warm WLED. Especially the luminous efficiency of the fabricated WLED can reach up to 66.89 lm W−1, which is much higher than the values reported for most CDs‐based WLED devices. Additionally, CD RTP can be applied to advanced invisible inks for information encryption due to its excellent water solubility and can also be exploited for advanced information anti‐counterfeiting by utilizing phosphorescent properties.

An Er3+-Doped Cs2NaScCl6 Lead-Free Double Perovskite with Efficient Broadband Visible to Near-Infrared Emission and Multimodal Upconversion Luminescence.

Lanthanide ions are widely used as dopants for halide perovskites for their broad energy level coverage from the visible to near-infrared (NIR) range. In this work, Cs2NaScCl6:Er3+ was synthesized by an improved solid-state reaction method, which showed effective NIR emission under ultraviolet excitation. Through calculations based on density functional theory and Bader charge analysis, it is shown that [ErCl6]3- octahedra show a strong localization effect in the Cs2NaScCl6:Er3+ lattice, which is conducive to the charge transfer process of Cl-Er3+, and charge transfer sensitization is responsible for the efficient visible to NIR luminescence of Er3+, where the NIR emission around λem = 1540 nm originated from the Er3+:4I13/2 → 4I15/2 transition with an ultrahigh photoluminescence quantum yield that reached ∼28.3%. Notably, Cs2NaScCl6:Er3+ also exhibited bright upconversion luminescence of green light (at 540 nm) under excitation by a variety of NIR laser diodes (808, 980, and 1550 nm) via self-sensitization processes.

High-Performance Planar Field-Emission Photodetector of Monolayer Tungsten Disulfide with Microtips.

Monolayer tungsten disulfide (ML WS2 ) is believed as an ideal photosensitive material due to its small direct bandgap, large exciton/trion binding energy, high carrier mobility, and considerable quantum conversion efficiency. Compared with other photosensitive devices, planar field emission (FE)-type photodetectors with a full-plane structure should simultaneously have rapider switching speed and lower power consumption. In this work, ML WS2 microtips are fabricated by electron beam lithography (EBL) way and used to construct a planar FE-type photodetector. By optimization design, ML WS2 with three microtips can exhibit the maximum current density as high as 52 A cm-2 (@300V µm-1 ), and the largest photoresponsivity is up to 6.8 × 105 A W-1 under green light irradiation, superior to that of many other ML transition metal dichalcogenide (TMDC) detectors. More interestingly, ML WS2 devices with microtips can effectively solve the contradictory problem between large photoresponsivity and rapid switching speed. The excellent photoresponse performances of ML WS2 with microtips should be attributed to their high carrier mobility, sharp emission edge, ultrahigh quantum yield, and unique planar FE device structure. Ourresearch may shed new light on exploring the fabrication technology and photosensitive mechanism of two dimensional (2D) material-based planar FE photodetectors.

Synthesis of a europium complex with ultrahigh quantum yield and its application as an invisible luminescent additive in pigments for preservation of cultural relics

A europium coordination compound [Eu2(ppip)2(PhCOO)6] (ppip is 1,2-diphenylimidazo[4,5-f][1,10]phenanthroline) has been synthesized and structurally characterized. In this symmetric dinuclear complex of octa-coordinated Eu(III) atom, both hanging phenyl rings in the ppip are twisted dramatically from the imidazophenanthroline part, leading to strong edge-to-face (T-type) C–H∙∙∙π interaction. This pale yellow stable complex possesses an ultrahigh luminescence quantum yield (84.2 ± 0.2%) under excitation at 365 nm, and hence is explored to be utilized in the preservation pigments for traditional Chinese paintings as an luminescent additive, which looks invisible under normal light, but exhibits bright red luminescence under UV excitation at a rather low percentage (0.02% wt).

N doped-carbon quantum dots with ultra-high quantum yield photoluminescent property conjugated with folic acid for targeted drug delivery and bioimaging applications

BackgroundImproving targeted therapy, and reducing adverse side effects of antitumor drugs toward normal cells with simultaneous bioimaging properties are being developed in pharmaceutical industries. In this study, N doped-carbon quantum dot (CQD) with ultra-high quantum yield (QY) was synthesized and its surface was modified with folic acid as the targeted anticancer agent. MethodsCQD was synthesized by one-step hydrothermal method. The impact of operating parameters such as pyrolysis temperature, time, and pH on the QY and surface charge was investigated. Then, the CQD surface was modified with folic acid as the targeted anticancer agent followed by doxorubicin (DOX) conjugation on the surface. Cytotoxicity of CQD-FA and CQD-FA-DOX upon 4T1, MCF7 and PC12 cell lines were examined. Furthermore, fluorescent microscopy imaging and flow cytometry analysis for various cell lines were applied to evaluate CQD-FA bioimaging property. In addition, the efficacy of the formulation on the BALB/c mice bearing breast cancer tumors was investigated. ResultsIn CQD preparation, average particle size of 7 nm was confirmed by the characterization results. With optimum synthesis conditions of pH = 11, time = 8 h and temperature = 160 °C, QY was about 90%. XPS analysis confirmed formation of N doped CQD. DOX loading efficiency was 88.6% and about 86% of the loaded DOX was released from CQD-FA-DOX after 72 h at pH = 5.5. Cytotoxicity analysis confirmed a higher toxicity effect of CQD-FA-DOX toward cancerous cell lines (4T1, MCF7) in comparison to free DOX. This nanocarrier could act smartly in identifying folate receptor positive cancerous cells and enter mainly by the receptor-mediated route. In vivo results showed that cellular internalization of CQD-FA-DOX was greater than free DOX, in which the tumor growth in mice treated with CQD-FA-DOX was lower than free DOX. In addition, ex vivo analysis confirmed lower side effects of CQD-FA-DOX on the main organs of mice in comparison to the free drug group. ConclusionThis new synthesized carrier can be a suitable platform for drug delivery applications with lower side effects, targeted cellular uptake and bioimaging properties.

A high-pressure-tolerant vapor-fed photocatalytic system for efficient water splitting

Efficient water-vapor splitting opens up a new strategy for developing scalable and corrosion-free solar-energy-harvesting systems. In a recent issue of Nature Communications, Takanabe and co-workers report a high-pressure-tolerant vapor-fed photocatalytic water-splitting system for highly efficient photocatalytic H2 evolution with an ultrahigh apparent quantum yield of 54% ± 4%.

Copper Iodide Inks for High-Resolution X-ray Imaging Screens

Copper-based halide scintillators have attracted considerable interest because of their high light yields, low detection limits, low toxicity, and moderate fabrication conditions. Here, we synthesized two Cu(I) iodide inks, comprising zero-dimensional Cu4I6(L1)2 nanoparticles (L1 = 1-propyl-1,4-diazabicyclo[2.2.2]octan-1-ium) and one-dimensional Cu4I6(L2)2 nanorods (L2 = 4-dimethylamino-1-ethylpyridinium) for X-ray imaging application. The Cu4I6(L1)2 nanoparticles and Cu4I6(L2)2 nanorods exhibited broadband green and yellow emission with an ultrahigh photoluminescence quantum yield of 95.3% and 92.2%, respectively. Consequently, the two Cu(I) iodide ink-based X-ray screens exhibited low detection limits of 96.4 and 102.1 nGy s–1, respectively, which are approximately 55 times lower than the dose required for standard medical diagnosis (5.5 μGy s–1). Importantly, both the scintillation screens exhibited extraordinary X-ray imaging resolutions exceeding 30 lp mm–1, more than double those of the conventional CsI:Tl and Ga2O2S:Tb scintillators. This study provides a new avenue for exploring high-resolution X-ray imaging screens on the basis of Cu-based halide ink for medical radiography and nondestructive detection.

Rapid microwave fabrication of red-carbon quantum dots as fluorescent on-off-on probes for the sequential determination of Fe(III) ion and ascorbic acid in authentic samples.

In this study, fluorescent red-carbon quantum dots (R-CQDs) with an ultrahigh fluorescence quantum yield of 45% were rapidly and easily synthesized by thermal pyrolysis of 2,5-diaminotoluene sulfate and 4-hydroxyethylpiperazineethanesulfonic acid using a one-step microwave-assisted hydrothermal approach. R-CQDs possessed the excitation-independent fluorescence property with the optimal emission peak at 607 nm under the excitation wavelength of 585 nm. R-CQDs exhibited excellent fluorescence stability under extremely harsh conditions in a pH range of 2-11, high ionic strength (1.8 M of NaCl), and long UV light irradiation time (160 min). The fluorescence quantum yield of these R-CQDs was as high as 45%, implying their preferable application in chemosensors and biological analysis. Because Fe3+ ion bound with R-CQDs and statically quenched the fluorescence of R-CQDs, the fluorescence intensity of R-CQDs was recovered after the addition of ascorbic acid (AA) via its redox reaction with Fe3+ ion. R-CQDs were developed as highly sensitive fluorescent on-off-on probes for sequentially sensing Fe3+ ions and AA. Under the optimal experimental conditions, the linear range for Fe3+ ion detection was 1-70 μM with a detection limit of 0.28 μM, and the linear range for AA detection was 1-50 μM with a detection limit of 0.42 μM. The successful detection of Fe3+ ions in authentic water samples and the successful sensing of AA in human body fluids and vitamin C tablets further proved the practical application prospects of this efficient strategy in the environmental protection and disease diagnosis fields.

Highly Emissive Organic Cage in Single-Molecule and Aggregate States by Anchoring Multiple Aggregation-Caused Quenching Dyes.

It remains a great challenge to design and synthesize organic luminescent molecules with strong emission in both dilute solution and aggregate state. Herein, an organic cage with dodecadansyl groups (D-RCC1) from an easy sulfonation reaction displays strong emissive behavior in dilute organic solution with a quantum yield of 42%. Moreover, D-RCC1 exhibits an ultrahigh quantum yield of 92% in the solid state, which is more than 3 times that of 27% for the model compound D-DEA. The results of the experiment and theoretical calculation show that the three-dimensional symmetrical skeleton of the organic cage anchored evenly by multiple dye molecules effectively satisfies both high local density and a symmetrical distribution of chromophores, which prevents the interaction of dye molecules and ensures that dye molecules have strong emission in both single-molecule and aggregate states.