Tunable Near-infrared Emission Research Articles

Antimony doping in A2ZnCl4 (A= Rb, Cs) metal halides enabling tunable near-infrared emission

Lead-free metal halides with stable and tunable emission have shown great promise for broad application prospects in the visible light range. However, it remains a fundamental challenge to realize tunable near-infrared (NIR) luminescence in these metal halide materials. Herein, a cation regulation strategy in zero-dimension organic metal halides A2ZnCl4:Sb3+ (A = Rb, Cs) to achieve tunable NIR luminescence is reported. The prepared A2ZnCl4:Sb3+ (A = Rb, Cs) halides exhibited efficient broadband NIR emission, which originates from self-trapped excitons of the [SbCl4]− polyhedron. Based on the regulation of cation, the [SbCl4]− tetrahedral distortion capacity changes, exciton–phonon coupling is enhanced, leading to a red shift of the emission wavelength. The results provide inspiration for the regulation of the self-trapped excitons luminescence of halides and demonstrate potential as a non-visible light source for night vision.

Sr2MgWO6:Ni2+-A highly efficient and tunable photoluminescence near-infrared phosphor for NIR-II light source applications

The rapid development of near-infrared (NIR) phosphorescent conversion light-emitting diodes (pc-LED) in imaging and detection indicates a strong demand for NIR-II region luminescent materials. Unfortunately, the lack of effective IR-II phosphors that can be excited by commercial blue LED chips has hindered the application of NIR spectroscopy. In this paper, we introduce a novel ultra-broadband NIR phosphor Sr2MgWO6:Ni2+ characterized by an emission peak at 1400 nm with a full width at half maximum (FWHM) of 237 nm. A tunable NIR emission from 1400 to 1485 nm is achieved by cation co-substitution of Ca2+ for Sr2+, and the corresponding FWHM can be modified from 237 to 292 nm. NIR-II pc-LEDs was fabricated by combining prepared near-infrared phosphors with blue LED chips to visually demonstrate their potential applications in authentication artistic works such as oil paintings. These results not only have theoretical significance for further understanding of the structure-property relationship of NIR-II luminescent materials, but also have reference value for developing more practical materials.

Copper nanoclusters electrochemiluminescence with tunable near-infrared emission wavelength for ultrasensitive detection of matrix metalloproteinase-2

Herein, the methionine (Met)/N-acetyl-L-cysteine (NAC) templated copper nanoclusters (Met/NAC-Cu NCs) with tunable near-infrared region (NIR) electrochemiluminescence (ECL) emission wavelength was firstly synthesized as emitter for the ultrasensitive detection of matrix metalloproteinase-2 (MMP-2). Significantly, the NAC played the role of template and reductant of cupric to acquire Cu NCs, and the surface defect regulator Met was used to connect NAC through -S-S- bond, which could heighten the surface defect of Cu NCs to continuously regulate the maximum ECL emission by successively controlling the molar ratio of Met and NAC, leading to the ECL emission wavelength of Cu NCs ranged from 680 nm to 750 nm. In addition, a rapid target triggered catalyst hairpin assembly (CHA) recycling amplification strategy was constructed through orderly and equidistantly arranging hairpin to increase its local concentration, resulting in greatly accelerated signal amplification efficiency and reaction rate. As a proof of concept, based on Met/NAC-Cu NCs as NIR ECL emitter and effective signal amplification tactic, a super-sensitive ECL biosensor was fabricated to detect target MMP-2 with the detection limit (LOD) as low as 1.65 fg/mL and successfully utilized for detecting of MMP-2 that from Hela and MCF-7 cancer cells. This research provided a wonderful avenue for regulating the optical performance of metal nanoclusters-based ECL emitters, and the developed neoteric NIR ECL emitter with the merits of less photochemical damage and deeper tissue penetration exhibited great potential in ultrasensitive biosensing and high-definition ECL imaging.

Creating an efficient and tunable near-infrared emission by using [Mg2+-Sn4+] chemical unit co-substitution in Ga2O3:Cr3+ phosphor

NIR phosphor-converted light-emitting diode (NIR pc-LED) has attracted many attentions for its promising applications in biomedical imaging, night vision, spectroscopy, and many other fields, while the discovery of broadband NIR phosphors with high external quantum efficiency (EQE) remains a challenge. Herein, a series of efficient and tunable broadband NIR-emitting Ga1.97-2xMgxSnxO3:0.03Cr3+ phosphors were synthesized via [Mg2+-Sn4+] substituting [Ga3+-Ga3+] in Ga2O3:Cr3+ system. As increase of substituting ratio x, a significant red-shift in the emission spectra from 726 to 793 nm with a full width at half maximum (FWHM) extended from 121 to 167 nm can be observed. All the samples have an EQE above 40% under 450 nm excitation; and the excitation peak in the blue light region remains unchanged, enabling these materials to be efficiently excited by blue LEDs. Finally, a NIR pc-LED device was fabricated by integrating the optimized Ga1.77Mg0·1Sn0·1O3:0.03Cr3+ phosphor on a blue LED chip, which exhibits a high NIR output power of 33.41 mW with a photoelectric conversion efficiency of 12.01% under a drive current of 100 mA. These results indicate that the obtained NIR phosphors may have potential in NIR pc-LEDs applications.

Dopant and compositional modulation triggered long-wavelength ultra-broadband and tunable NIR emission in MgO: Cr3+ phosphor for NIR spectroscopy applications

Efficient ultra-broadband near-infrared (NIR) phosphors with long-wavelength ( λ max > 850 nm) and wide full width at half-maximum (FWHM, >200 nm) have sparked tremendous interest, demonstrating their immense potential in NIR spectroscopy technology. Nevertheless, the development of NIR spectroscopy technology suffers from the restricted capability to efficiently emit the ultra-broadband NIR light. Herein, the synergetic enhancement strategy of heterogeneous substitution and compositional modulation was applied to create a novel Cr 3+ doped long-wavelength ultra-broadband MgO: Cr 3+ , Ga 3+ phosphor, which exhibited a long-wavelength ultra-broadband NIR emission ( λ max = 850 nm) covering the range of 650–1300 nm on the electromagnetic spectrum with the FWHM of more than 200 nm under the excitation of 468 nm light. Furthermore, the tunable NIR emission from 818 nm to 862 nm with an optimized quantum efficiency of 30% was accomplished by the Ga 3+ ions substitution and Cr 3+ ions modulation. The phosphor exhibited remarkable thermal stability up to 100 °C, remaining 83% of the integrated emission intensity at room temperature. A prototype of the NIR phosphor-converted LED (pc-LED) demonstrated that the novel MgO: Cr 3+ , Ga 3+ phosphor possessed a relatively strong NIR output power (15.05 mW at 100 mA driven current) with a photoelectric conversion efficiency of 5.53%, which is impressive compared with other Cr 3+ -doped long-wavelength ultra-broadband phosphors. This work not only proposes a novel long-wavelength ultra-broadband NIR phosphors with industrialization and great application prospect in night vision but highlights a synergetic enhancement strategy to effectively boost the performance of long-wavelength ultra-broadband NIR pc-LED light sources.

Tunable near-infrared emission and three-photon absorption in lanthanide-doped double perovskite nanocrystals.

Cs2AgInCl6 double perovskite (DP) nanocrystals (NCs) are an emerging class of materials with promising application potential in photonics/optoelectronics owing to their nontoxicity, direct bandgap, and high thermal and moisture stability. These NCs are, however, rarely explored for nonlinear optical (NLO) applications. Herein, we present a comprehensive investigation of the photophysical and nonlinear optical properties of erbium- (Er) and ytterbium (Yb)-doped Cs2AgInCl6 nanocrystals (denoted as Er-DP and Yb-DP, respectively). Temperature-dependent photoluminescence of these NCs was analyzed to estimate their exciton binding energy, Huang-Rhys parameter (S), and electron-phonon coupling strength, which are of fundamental interest to gain an in-depth understanding of the material systems. Femtosecond Z-scan experiments with 800 nm excitation revealed the reverse saturable absorption (RSA) behavior owing to three-photon absorption (3PA). The obtained values of the 3PA coefficients were 1.35 × 10-4 and 1.64 × 10-4 cm3 GW-2, respectively, and the nonlinear refractive indices were estimated to be 1.02 × 10-15 and 1.15 × 10-15 cm2 W-1, respectively, for Er-DP and Yb-DP. These values are superior to those obtained in undoped Cs2AgInCl6 NCs. The physical parameter, Kane energy, which is closely related to the magnitude of the oscillator strength, was estimated to be 25 eV and 26 eV for Er-DP and Yb-DP, respectively. As a proof-of-concept application, we further obtained the optical limiting onset and figure of merit to reveal their prospect as an optical limiter and in photonic switching application. With such emission and nonlinear optical properties, we anticipate that lanthanide-doped Cs2AgInCl6 NCs can be used for designing eco-friendly nonlinear optoelectronic/photonic devices.

Chemical unit co-substitution enabling broadband and tunable near-infrared emission in garnet-type Lu3Sc2Ga3O12:Cr3+ phosphors

Although near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are desired for non-visible light source applications, the design of broadband NIR phosphors remains a challenge. Inspired by the chemical unit co-substitution strategy for the modification of composition and local structure, we realize a tunable redshift emission from 706 to 765 nm in garnet-type Lu3Sc2Ga3O12:Cr3+ with a broadened full width at half maximum and enhanced photoluminescence intensity by introducing a [Mg2+-Si4+] unit into the [Sc3+-Ga3+] couple. Structural and spectral analyzes demonstrate that the co-substitution reduces the local symmetry and crystal field strength of the [CrO6] octahedra, thus leading to inhomogeneous widening of the 4T2→4A2 emission and enhanced blue absorption. Furthermore, the 4T2→4A2 emission exhibits a phonon-assisted character at low temperatures due to the thermal coupling effect with the 2E level. The fabricated NIR pc-LED based on the optimized NIR phosphor exhibits excellent potential in night vision and imaging applications.

Coupling between Emissive Defects on Carbon Nanotubes: Modeling Insights.

Covalent functionalization of single-walled carbon nanotubes (SWCNTs) with organic molecules results in red-shifted emissive states associated with sp3-defects in the tube lattice, which facilitate their improved optical functionality, including single-photon emission. The energy of the defect-based electronic excitations (excitons) depends on the molecular adducts, the configuration of the defect, and concentration of defects. Here we model the interactions between two sp3-defects placed at various distances in the (6,5) SWCNT using time-dependent density functional theory. Calculations reveal that these interactions conform to the effective model of J-aggregates for well-spaced defects (>2 nm), leading to a red-shifted and optically allowed (bright) lowest energy exciton. H-aggregate behavior is not observed for any defect orientations, which is beneficial for emission. The splitting between the lowest energy bright and optically forbidden (dark) excitons and the pristine excitonic band are controlled by the single-defect configurations and their axial separation. These findings enable a synthetic design strategy for SWCNTs with tunable near-infrared emission.

Li/Na substitution and Yb3+ co-doping enabling tunable near-infrared emission in LiIn2SbO6:Cr3+ phosphors for light-emitting diodes

SummaryNear-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) has great potential in non-invasive detection, while the discovery of tunable broadband NIR phosphor still remains a challenge. Here, we report that Cr3+-activated LiIn2SbO6 exhibits a broad emission band ranging from 780 to 1400 nm with a full width at half maximum (FWHM) of 225 nm upon 492 nm excitation. The emission peaks are tuned from 970 to 1020 nm together with considerable broadening of FWHM (∼285 nm) via Li/Na substitution. Depending on Yb3+ co-doping, a stronger NIR fluorescence peak of Yb3+ appears with improved thermal resistance, which is ascribed to efficient energy transfer from Cr3+ to Yb3+. An NIR pc-LED package has been finally designed and demonstrated a remarkable ability to penetrate pork tissues (∼2 cm) so that the insertion depth of a needle can be observed, indicating that the phosphor can be applied in non-destructive monitoring.

Near-infrared persistent luminescence in Mn4+ doped perovskite type solid solutions

Persistent luminescent phosphors with near-infrared emission have attracted attention in recent years for their promising bio-imaging applications. In the development of persistent materials in the near-infrared wavelengths, Mn4+ is regarded as a promising candidate owing to the 2Eg → 4A2g emission in the deep-red or near-infrared range. In this work, a series of Mn4+ doped perovskite type LaAl1-xGaxO3 and La1-xGdxAlO3 solid solutions with different compositions were successfully prepared using a high temperature solid state reaction method. Mn4+ occupied octahedral positions to substitute Al3+ or Ga3+ in these solid solutions and the 2Eg → 4A2g emission of Mn4+ was tailored by the different local environments of the hosts. Tunable NIR persistent luminescence was achieved by the crystal field control and composition modification. The trap levels of these solid solutions were investigated using thermoluminescence measurements. This kind of perovskite type-based solid solution with tunable near-infrared emission is highly desirable for medical imaging applications.

Biocompatible off-stoichiometric copper indium sulfide quantum dots with tunable near-infrared emission via aqueous based synthesis.

The present study reports an aqueous synthesis approach towards off-stoichiometric copper indium sulfide quantum dots with emissions in the near-infrared spectral range. The photoluminescence properties of the dots, and in particular the appearance of dual emission at high Cu deficiency, were studied with temperature-dependent steady-state and transient photoluminescence spectroscopy.

Tunable near-infrared emission and fluorescent lifetime of PbSe quantum dot-doped borosilicate glass

Abstract PbSe quantum dots (QDs) were used to dope borosilicate glass with a composition of SiO 2 -B 2 O 3 -Al 2 O 3 -ZnO-AlF 3 -Na 2 O-PbO-Se, which was prepared using the conventional melt-quenching technique followed by heat treatment. We observed a broad near infrared (NIR) emission (960–1353 nm) band with a full-width-at-half-maximum (FWHM) value of 168–294 nm and a notable Stokes shift (139–167 nm), which depended on the temperature and duration of the heat treatment. At room temperature, the photoluminescence (PL) lifetime was approximately 1.24–1.92 μs, and it showed a clear dependence on the size and concentration of the QDs. The large FWHM and strong NIR emission of the PbSe QD-doped borosilicate glass may facilitate its application in NIR optical amplifiers and lasers.

Development of Ion Chemosensors Based on Porphyrin Analogues.

Sensing of metal ions and anions is of great importance because of their widespread distribution in environmental systems and biological processes. Colorimetric and fluorescent chemosensors based on organic molecular species have been demonstrated to be effective for the detection of various ions and possess the significant advantages of low cost, high sensitivity, and convenient implementation. Of the available classes of organic molecules, porphyrin analogues possess inherently many advantageous features, making them suitable for the design of ion chemosensors, with the targeted sensing behavior achieved and easily modulated based on their following characteristics: (1) NH moieties properly disposed for binding of anions through cooperative hydrogen-bonding interactions; (2) multiple pyrrolic N atoms or other heteroatoms for selectively chelating metal ions; (3) variability of macrocycle size and peripheral substitution for modulation of ion selectivity and sensitivity; and (4) tunable near-infrared emission and good biocompatibility. In this Review, design strategies, sensing mechanisms, and sensing performance of ion chemosensors based on porphyrin analogues are described by use of extensive examples. Ion chemosensors based on normal porphyrins and linear oligopyrroles are also briefly described. This Review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing high-performance ion chemosensors based on porphyrin analogues and other relevant compounds.

Glycerol-regulated facile synthesis and targeted cell imaging of highly luminescent Ag2Te quantum dots with tunable near-infrared emission

In this work, highly luminescent and emission tunable Ag2Te quantum dots (QDs) were facilely prepared by using water-dispersed glycerol as viscous solvent and CH3COOAg/Na2TeO3 as Ag/Te precursors. Viscous glycerol was utilized to slow the nucleation and growth of QDs at 200°C, and enabled the isolation of QDs with different emission wavelengths. Experimental results revealed that the as-prepared Ag2Te QDs exhibited tunable near-infrared emission from 930 to 1084nm, high photoluminescence (PL) quantum yields (QYs, more than 20%), good photostability and low cytotoxicity. After surface coating of a thin silica shell (∼1.4nm), the resulting NH2 terminated Ag2Te@SiO2-NH2 displayed enhanced PL QYs, higher photostability and biocompatibility when compared with the original Ag2Te QDs. Through a facile carboxy-amine coupling, folic acid (FA) was grafted with Ag2Te@SiO2-NH2 to form Ag2Te@SiO2-FA nanocomposites, which were used for targeted PL imaging of folate receptor over-expressed tumor cells.

Facile synthesis of homogeneous CuInS2 quantum dots with tunable near-infrared emission

Ternary CuInS2 quantum dots (QDs) with homogeneous and tunable emission ranging from 693 to 835 nm were synthesized via a one-pot thermolysis route. The fluorescence of CuInS2 QDs was greatly enhanced via surface passivation of ZnS layers.

Quantum Dot-Doped Glasses and Fibers: Fabrication and Optical Properties

Quantum dot-doped glasses have been the hotspot for their excellent electronic and optical properties. Owing to its tunable and broadband near-infrared (NIR) emission by controlling the size and distribution of QDs, QD-doped glasses and fibers are potentially applied in photoelectric devices. In this review, we mainly introduce the preparation, tunable emission, and multi-wavelength optical amplification of QD-doped glasses. Due to their excellent optical performances, the fabrication of QD-doped glass fibers is also presented, containing the successful fabrication of QD-doped glass fibers with tunable NIR emission. Furthermore, the achievements and existing problems about QD-doped glasses and fibers are also proposed with several prospects. These QD-doped glasses and fibers show promising applications as the gain medium of NIR broadband fiber amplifiers and tunable fiber lasers.

Tunable near-infrared emission of binary nano- and mesoscale GUMBOS

Mixtures of GUMBOS were used to form binary nanomaterials with tunable emission spectra due to Förster resonance energy transfer (FRET).

Ultrasmall paramagnetic near infrared quantum dots as dual modal nanoprobes

Gadolinium-functionalized CdHgTe–ZnS core–shell quantum dots with ultrasmall particle size and tunable near-infrared emission were synthesized as a dual-modal nanoprobe for in vivo fluorescence and magnetic resonance imaging.

Broadband tunable near-infrared emission of Bi-doped composite germanosilicate glasses

Download options Please wait... Article information DOI https://doi.org/10.1039/C2JM15606G Article type Paper Submitted 02 Nov 2011 Accepted 12 Dec 2011 First published 06 Jan 2012 Download Citation J. Mater. Chem., 2012,22, 3154-3159 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Broadband tunable near-infrared emission of Bi-doped composite germanosilicate glasses N. Zhang, J. Qiu, G. Dong, Z. Yang, Q. Zhang and M. Peng, J. Mater. Chem., 2012, 22, 3154 DOI: 10.1039/C2JM15606G To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Na Zhang Jianrong Qiu Guoping Dong Zhongmin Yang Qinyuan Zhang Mingying Peng

Near-infrared optical sensors based on single-walled carbon nanotubes

Molecular detection using near-infrared light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole-blood media. Carbon nanotubes have a tunable near-infrared emission that responds to changes in the local dielectric function but remains stable to permanent photobleaching. In this work, we report the synthesis and successful testing of solution-phase, near-infrared sensors, with beta-D-glucose sensing as a model system, using single-walled carbon nanotubes that modulate their emission in response to the adsorption of specific biomolecules. New types of non-covalent functionalization using electron-withdrawing molecules are shown to provide sites for transferring electrons in and out of the nanotube. We also show two distinct mechanisms of signal transduction-fluorescence quenching and charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biology.