Concentration effect of the near-infrared quantum cutting of 1788-nm luminescence of Tm^(3+) ion in(Y_(1-x)Tm_x)_3Al_5O_(12) powder phosphor

In the present paper, the concentration effect of near-infrared quantum cutting of Tm3＋ ion in （Y1-xTmx）3Al5Ol2 powder phosphor is studied by means of experiments and calculations. In addition, the absorption spectra, visible-to-near- infrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that （Y1-xTmx）3Al5O12 powder phosphor has a strong four-photon near-infrared quantum cutting luminescence of 1788.0-nm 3F4 →3H6 fluores- cence of Tm3＋ ion, when excited by 357.0-nm light. It is also found that the up-limit of the four-photon near-infrared quantum cutting luminescence efficiency of （Yo.700Tmo.300）3Al5 O12 powder phosphor is approximately 302.19%. To the knowledge of the authors, this is the first time that a near-infrared quantum cutting efficiency up-limit exceeding 300% has been reported. The results of this manuscript are valuable in aiding the probing of the new generation Ge solar cell.

Specific Recognition of Breast Cancer Cells In Vitro Using Near Infrared-Emitting Long-Persistence Luminescent Zn_3Ga_2Ge_2O_(10):Cr^(3+)Nanoprobes

In this paper, near-infrared emitting long-persistence luminescent Zn3Ga2Ge2O10:Cr3?(ZGG) nanoparticles with diameters of 30–100 nm and bright luminescence were prepared by a sol–gel synthesis method. After the surface amination, the nanoparticles were further bioconjugated with breast cancer-specific monoclonal antibody(anti-Ep CAM) to form ZGG-Ep CAM nanoprobes which can specifically target breast cancer cell lines(MCF7) in vitro. The results of in vitro images show that the luminescence signals from the cells treated with ZGG-Ep CAM nanoprobes are stronger than those from cells treated with ZGG-unconjugated antibody, indicating that the prepared ZGG-Ep CAM nanoprobes possessed excellent specific recognition capability. Furthermore, due to their long afterglow properties, the imaging could persist more than 1 h. Therefore, these nanoprobes could not only provide a high specificity detection method for cancer cells but also realize the long-time monitoring. Developed near-infrared emitting long-persistence luminescent nanoprobes will be expected to find new perspectives for cell therapy research and diagnosis applications.

A New Heptamethine Cyanine-Based Near-Infrared Fluorescent Probe for Divalent Copper Ions with High Selectivity

A new near-infrared fluorophore 2-(2-Aminoethyl) pyridine-tricarbocyanine (1) was rationally designed and synthe-sized as a fluorescent probe for detection of Cu2+ with high selectivity. The response of Probe 1 is based on the fluorescence quenching upon binding to Cu2+. The sensing performance of the proposed Cu2+-sensitive Probe 1 was then investigated. The probe can be applied to the quantification detection of Cu2+ with a linear concentration range covering from 4.8 × 10-7 to 1.6 × 10-4 mol/L and a detection limit of 9.3 × 10-8 mol/L. The experimental results showed that the response of 1 to Cu2+ was independent of pH in medium condition (pH 6.0-8.0), and exhibited excellent selectivity towards Cu2+ over other common metal cations.

CHARACTERIZATION AND LUMINESCENCE PROPERTIES OF THE DYE-DOPED POLYMER LANGMUIR-BLODGETT FILMS

1,1,4,4-Tetraphenyl-1,3-butadiene (TPB) was successfully introduced into the polymer multilayer films by means of Langmuir-Blodgett (LB) technique. Results of UV-VIS spectra and X-ray diffraction showed that the uniform films had a layer structure similar to the superlattice of organic multiple quantum wells. The electroluminescence (EL) devices fabricated from the doped polymer LB films emitted blue light. Compared with the casting films, the photoluminescence (PL) and EL spectra showed that the exciton energy shifts to higher and the half-width of the emission peak becomes narrower due to exciton confinement effect.

Near-infrared emitting metal halide materials:Luminescence design and applications

Near-infrared(NIR)luminescent metal halide(LMH)materials have attracted great attention in various optoelectronic applications due to their low-temperature solution-processable synthesis,abundant crystallographic/electronic structures,and unique optoelectronic properties.However,some challenges still remain in their luminescence design,performance improvement,and application assign-ments.This review systematically summarizes the development of NIR LMHs through classifying NIR luminescent origins into four major categories:band-edge emission,self-trapped exciton(STE)emission,ion emission,and defect-related emission.The luminescence mechanisms of different types of NIR LMHs are discussed in detail by analyzing typical examples.Reasonable strategies for design-ing and optimizing luminescence/optoelectronic properties of NIR LMHs are summarized,including bandgap engineering,self-trapping state engineering,chemical composition modification,energy transfer,and other auxiliary strategies such as improvement of synthesis scheme and post-processing.Furthermore,application prospects based on the optoelectronic devices are revealed,including phosphor-converted light-emitting diodes(LEDs),electroluminescent LEDs,pho-todetectors,solar cells,and x-ray scintillators,as well as demonstrations of some related practical applications.Finally,the existing challenges and future perspec-tives on the development of NIR LMH materials are critically proposed.This review aims to provide general understanding and guidance for the design of high-performance NIR LMHs materials.

Near-infrared small molecular fluorescent dyes for photothermal therapy

Near-infrared(NIR)fluorescent dyes based on small organic molecules are characterized with low cytotoxicity,good biocompatibility and minimum interference from auto-fluorescence background,which are widely used in tumor diagnosis.Intensive research on molecular properties and photothermal properties of fluorescent dyes have been explored for non-invasive photothermal treatment of cancer.In this review,we focus on the development of imaging-induced photothermal therapy of small molecules and classification according to the structures of organic molecules including cyanines,phthalocyanines,rhodamine analogues and BODIPYs.

Lanthanide-doped near-infrared Ⅱ luminescent nanoprobes for bioapplications

Luminescent biosensing in the second nearinfrared(NIR-II) region is featured with superior spatial resolution and high penetration depth by virtue of the suppressed scattering of long-wavelength photons. Hitherto, the reported NIR-II nanoprobes are mostly based on carbon nanotubes, organic fluorophores or semiconducting quantum dots. As an alternative, trivalent lanthanide ions(Ln3+) doped nanoparticles have been emerging as a novel class of promising nanoprobes. In this review, we highlight the recent progress in the design of highly efficient Ln3+-doped NIR-II nanoparticles towards their emerging bioapplications, with an emphasis on autofluorescence-free bioimaging, sensitive bioassay, and accurate temperature sensing. Moreover, some efforts and challenges towards this rapidly expanding field are envisioned.

Near-infrared luminescent Nd^(3+)/Yb^(3+)-codoped metal-organic framework for ratiometric temperature sensing in physiological range

Self-calibrating luminescent thermometry employing luminescence within the optical transparency windows provides a promising prospect for temperature measurement in the biological fields.In this work,a new Nd^(3+)/Yb^(3+)-codoped metal-organic framework Nd_(0.95)Yb_(0.05)BPTC showing threedimensional anionic network,obtained by reacting ligand[1,1’-biphenyl]-3,3’,5,5’-tetracarboxylic acid(H4BPTC)with Nd^(3+)and Yb^(3+)ions under solvothermal conditions,is reported.Upon 808 nm photoexcitation,Nd_(0.95)Yb_(0.05)BPTC simultaneously emits the characteristic near-infrared luminescence of Nd^(3+)and Yb^(3+)ions based on the efficient energy transfer from Nd^(3+)to Yb^(3+)ions.In addition,the emission intensity ratio of Yb^(3+)and Nd^(3+)shows good exponential-like response to temperature in the physiological range of 293-323 K.The feature properties of Nd_(0.95)Yb_(0.05)BPTC include near-infrared absorption and emission,favorable temperature sensitivity and accurate temperature uncertainty,as well as good chemical stability,making such system useful in biomedical applications.

Near-infrared dyes, nanomaterials and proteins

Taking the advantage of reduced scattering and low autofluorescence background, the NIR fluorescence probes, such as fluorescence proteins, organic molecules and nanoparticles, not only hold the promise of in vivo imaging of biological processes in physiology and pathology with high signal-to-noise ratio, but also for clinical diagnosis. In this review, we provide an overview of the recent progress on NIR probes,focusing on fundamental mechanisms of NIR dyes and nanoparticles, and protein engineering strategies for NIR proteins.

Visible and near-infrared light activated azo dyes

The photoisomerization properties of azo derivatives have been widely used in the fields of materials and biology.One serious restriction to the development of functional azo-based materials is the necessity to trigger switching by UV light,which damage the corresponding surfaces and penetrate only partially through the matter.Therefore,developing the visible and near-infrared light activated azo switches can solve this problem.This review provides a summary of molecular design strategies for driving the isomerization of azo derivatives with visible light and near-infrared light:(1) smart design directly excited by visible light,(2) the addition of upconversion nanoparticles,(3) the employment of twophoton absorption,(4) indirect excitation in combination with metal sensitizer.

Organic Near-Infrared Luminescent Materials Based on Excited State Intramolecular Proton Transfer Process

Organic near-infrared(NIR)luminescent materials have captured intense research interest owing to their potential applications in optical communication,data storage,bioimaging,sensing and night vision.Excited state intramolecular proton transfer(ESIPT)process with absorption in normal form while emission in tautomer form can lead to a distinct redshift emission,based on which,a lot of organic NIR luminescent materials were designed.Because of attractive features such as ultrahigh sensitivity to the surroundings,large Stokes shift,and inherent four level system,ESIPT based NIR luminescent materials are supposed to be ideal fluorescent probes and gain materials.In this review,first,organic near-infrared luminescent materials based on ESIPT process are summarized according to the core structures.Second,recent advances of ESIPT-based organic near-infrared fluorescent probes and organic NIR lasers are reviewed.Finally,the current challenges and prospects of ESIPT-based organic NIR luminescent materials are introduced.

A 4d-4f heterometallic coordination polymer: Synthesis, crystal structure and near-infrared luminescent properties

A 4d-4f heterometallic coordination polymer, [AgNd（pydc）2].2H2O （1） （H2pydc=pyridine-3,4-dicarboxylic acid）, was synthesized under hydrothermal conditions, and fimher characterized by elemental analysis, IR, thermogravimetric analysis and single-crystal X-ray dif- fraction. Complex 1 featured a three-dimensional （3D） framework containing one-dimensional （1D） channels occupied by free water molecules, which was constructed from 1D inorganic heterometallic chains and linear pydc linkers. To our knowledge, complex 1 represented a rare example of 3D open-framework 4d-4f heterometallic coordination polymer. After removal of the water molecules fi＇om complex 1, the remaining material had high thermal stability. Moreover, the near-infrared luminescent properties of 1 were also investigated in the solid state.

Advances in Polymethine Dyes for Near-Infrared Organic Photodiodes

Near-infrared organic photodiodes (NIR OPDs) have tremendous potential in industrial, military, and scientific applications, due to their unique features of lightweight, low toxicity, high structural flexibility, cooling-system-free, etc. However, the overall performance of currently available NIR OPDs still lags behind the commercial inorganic photodetectors, ascribed to the critical challenge of realizing organic semiconductors with sufficiently low optical bandgap and excellent optoelectronic properties simultaneously. Among various types of NIR-absorbing organic semiconductors, polymethine dyes not only possess advantages of simple synthesis and structural diversity, but also show fascinating optical and aggregation features in the solid state, making them attractive material candidates for NIR OPDs. In this review, after a brief introduction of NIR OPDs and polymethine dyes, we comprehensively summarize the advances of polymethine dyes for broadband and narrowband NIR OPDs, and further introduce their applications in all-organic optical upconversion devices and photoplethysmography sensors. In particular, the relationship between the chemical structure and the aggregation behaviors of polymethine dyes and the device performance is carefully discussed, providing some important molecular insights for developing high performance NIR OPDs.

New Soluble Near-Infrared Dyes Based on Terrylene Diimides with Four Aromatic Heterocycles

Terrylene diimides with four aromatic heterocycles(AHTDIs)were synthesized under Stille Cross-coupling conditions and fully characterized by NMR and mass spectrometry.The aggregation of the terrylene diimide(TDI)was suppressed by four heterocycles substituents on the bay region,and these AHTDIs exhibited good solubility in common organic solvents.The effects of the substituted groups on the optical and electrochemical properties were also investigated.The introduction of four aromatic heterocycles on the bay of TDI resulted in significant red-shifts of the absorption peak(100 nm),corresponding to a decrease in the band gap from 1.82 to 1.50 eV.Furthermore,with four rich electron aromatic heterocycles,the AHTDIs showed 280 mV negative-shifts of first oxidation poten-tials and a new oxidation wave,corresponding to an increase in the HOMO levels from−5.60 to−5.28 eV.

Upconversion Luminescence of Er^3＋ and Co-Doped Er^3＋/Yb^3＋ Novel Transparent Oxyfluoride Glasses and Glass Ceramics： Spectral and Structural Properties

Transparent oxyfluoride silicate precursor glasses and glass ceramics with the novel composition （1） SiO2-PbO-PbFE-Er2O3, （2） SiO2-GeOE-PbO-PbFE-Er2O3 （3） SiO2-Al2O3-Y2O3-Na2O-NaF-LiF-Er2O3-YbF3 doped with Er^3＋ and co-doped with Er^3＋/Yb^3＋ ions were synthesized. X-ray diffraction analysis （XRD） and Er3＋ absorption spectra revealed precipitation of PbF2 nanocrystals dispersed in the glassy matrix. Under 980 nm laser excitation, intense green, red and near IR bands of upconversion luminescence （UCL） were recorded both before and after heat treatment. In the glass ceramics the upconversion intensity increased significantly. To our knowledge, for the first time the composition of the glass ceramics characterized by the small-angle neutron scattering （SANS） showed the cluster organization of PbF2 nanocrystals.

Benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole-porphyrin-based near-infrared dyes

Benzo[1,2-c;4,5-cʹ]bis[1,2,5]thiadiazole(BBT)has intrinsic diradical character and herein it is used to construct organic near-infrared(NIR)dyes together with the aromatic porphyrin unit.Three BBT-porphyrin hybrid dyes 1-3 with different linkage modes are synthesized by Pd-catalyzed Sonogashira crosscoupling between meso-ethynylene porphyrin units and monobromo-/dibromo-BBT,or through unexpected homocoupling between the BBT units.They all possess small open-shell diradical character and display intense NIR absorption in the range of 800-1000 nm.They also exhibit amphoteric redox behavior.BBT-based diradicaloids are thus good candidates for organic NIR dyes.

基于钙钛矿量子点/染料的夹层型高效率荧光太阳能集光器

构建多节结构是扩大荧光吸收和发射光谱的有效技术,进而提升荧光太阳能集光器的效率。本研究使用CTAB作为配体修饰的CsPbBr_(3)量子点、染料Yellow083、染料Red305作为荧光材料,EVA作为聚合物波导材料制备钙钛矿量子点/染料的夹层结构的荧光太阳能集光器。通过设计单夹层/多夹层结构可以起到扩大吸收光谱、提高光学效率、增加荧光材料稳定性、降低荧光物质毒性风险以及保护环境的作用。以CTAB作为配体修饰的CsPbBr_(3)量子点、染料Yellow083和染料Red305分别作为荧光材料的单夹层荧光太阳能集光器的外部光学效率(η_(opt))分别可以达到4.50%、4.86%以及10.92%。以CTAB作为配体修饰的CsPbBr_(3)量子点/染料Yellow083、染料Red305单层荧光太阳能集光器组合形成的双夹层结构的外部光学效率(η_(opt))分别可以达到6.04%和11.32%。我们进一步对3种荧光材料组合形成的三夹层荧光太阳能集光器进行JV测试,得到其η_(opt)可以达到11.95%,本研究也为制备钙钛矿量子点/染料的多夹层的荧光太阳能集光器提供了一种新思路。

Recent progress in engineering near-infrared persistent luminescence nanoprobes for time-resolved biosensing/bioimaging

Persistent luminescence nanoprobes (PLNPs) can remain luminescent after ceasing excitation.Due to the ultra-long decay time of persistent luminescence (PersL),autofluorescence interference can be efficiently eliminated by collecting PersL signal after autofluorescence decays completely,thus the imaging contrast and sensing sensitivity can be significantly improved.Since near-infrared (NIR) light shows reduced scattering and absorption coefficient in penetrating biological organs or tissues,near-infrared persistent luminescence nanoprobes (NIR PLNPs) possess deep tissue penetration and offer a bright prospect in the areas of in vivo biosensing/bioimaging.In this review,we firstly summarize the design of different types of NIR PLNPs for biosensing/bioimaging,such as transition metal ions-doped NIR PLNPs,lanthanide ions-doped NIR PLNPs,organic molecules-based NIR PLNPs,and semiconducting polymer self-assembled NIR PLNPs.Notably,organic molecules-based NIR PLNPs and semiconductor self-assembled NIR PLNPs,for the first time,were introduced to the review of PLNPs.Secondly,the effects of different types of charge carriers on NIR PersL and luminescence decay of NIR PLNPs are significantly emphasized so as to build up an in-depth understanding of their luminescence mechanism.It includes the regulation of valence band and conduction band of different host materials,alteration of defect types,depth and concentration changes caused by ion doping,effective radiation transitions and energy transfer generated by different luminescence centers.Given the design and potential of NIR PLNPs as long-lived luminescent materials,the current challenges and future perspective in this rapidly growing field are also discussed.

D-A-D structured selenadiazolesbenzothiadiazole-based near-infrared dye for enhanced photoacoustic imaging and photothermal cancer therapy

Near-infrared(NIR)small molecular organic dyes as photothermal agents for cancer photothermal therapy(PTT)have attracted considerable research attention.Herein,two donor-acceptor-donor(D-A-D)structured NIR dyes,BBTT and SeBTT,are rationally designed,where the only difference is one heteroatom within the acceptor unit varying from sulfur to selenium(Se).More importantly,SeBTT NPs exhibit stronger NIR absorbance and higher photothermal conversion efficiency(PTCE≈65.3%).In vivo experiments illustrate that SeBTT NPs can be utilized as a high contrast photoacoustic imaging(PAI)agent,and succeed in tumor suppression without noticeable damage to main organs under NIR photoirradiation.This study presents an effective molecular heteroatom surgery strategy to regulate the photothermal properties of NIR small molecules for enhanced PAI and PTT.

Silica shell-assisted synthetic route for mono-disperse persistent nanophosphors with enhanced in vivo recharged near-infrared persistent luminescence

Near-infrared （NIR） persistent-luminescence nanoparticles have emerged as a new class of background-free contrast agents that are promising for in vivo imaging. The next key roadblock is to establish a robust and controllable method for synthesizing monodisperse nanoparticles with high luminescence brightness and long persistent duration. Herein, we report a synthesis strategy involving the coating/etching of the SiO2 shell to obtain a new class of small NIR highly persistent luminescent ZnGa2O4：Cr^3＋,Sn^4＋（ZGOCS） nanoparticles. The optimized ZGOCS nanoparticles have an excellent size distribution of -15 nm without any agglomeration and an NIR persistent luminescence that is enhanced by a factor of 13.5, owing to the key role of the SiO2 shell in preventing nanoparticle agglomeration after annealing. The ZGOCS nanoparticles have a signal-to-noise ratio -3 times higher than that of previously reported ZnGa204：Cr^3＋ （ZGC-1） nanoparticles as an NIR persistent-luminescence probe for in vivo bioimaging. Moreover, the persistent-luminescence signal from the ZGOCS nanoparticles can be repeatedly re-charged in situ with external excitation by a white light- emitting diode; thus, the nanopartides are suitable for long-term in vivo imaging applications. Our study suggests an improved strategy for fabricating novel high-performance optical nanoparticles with good biocompatibility.