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- Abstract：Based on the reduction of photon reflection， scattering and spontaneous fluorescence， NIR-II window enables high resolution and signal-to-noise ratio biofluorescence imaging， which plays an important role in a variety of biomedical applications. The construction of Donor-Acceptor-Donor structure is an effective method for the design of NIR-II small organic molecules. NIR-II small organic molecules based on benzothiadiazole structure can not only realize optical imaging， but also realize phototherapeutics by utilizing the light-activated excited state energy conversion. This review summarizes the research advances of NIR-II small organic molecules based on benzobisthiadiazole （BBT） and ［1，2，5］thiadiazolo［3，4-g］quinoxaline （TQ） in bioimaging and image-guided therapy， and prospects of the design and application of NIR-II small organic molecules in the future are presented.Keywords：NIR-II;benzothiadiazole;bioimaging;phototherapeutics
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Published：2023-05-27 - Abstract：This paper proposes a strategy to successfully realize ultra-thin transparent conductive Ag thin films with excellent surface， optical， and electrical properties by introducing a silver oxide seed layer onto the surface of a glass substrate. Firstly， a 1-nm-thick Ag film is evaporated onto a glass substrate by thermal deposition and then treated with oxygen plasma to generate a silver oxide seed layer. The seed layer can alleviate the random migration of Ag atoms and improve the nucleation density of the subsequently deposited Ag atoms， thus promoting the film formation of Ag atoms. An efficient phosphorescent organic light-emitting device was fabricated using the realized ultra-thin transparent silver oxide/silver film as an anode. The device's maximum current efficiency and power efficiency are 60.4 cd·A-1 and 63.2 lm·W-1， respectively， 1.45 and 1.60 times higher than those of the conventional ITO-based devices. The results show that the ultra-thin transparent Ag thin film with silver oxide as a seed layer is a highly promising transparent conductive electrode.Keywords：Ag2O;air plasma;transparent anode;OLED
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Published：2023-05-26 - Abstract：Superluminescent diode （SLD） has optical characteristics such as high power， wide spectrum and low coherence， and has high application value in the fields of optical fiber communication， industrial defense， biological imaging and trace gas detection. This paper focuses on the output power and spectral bandwidth characteristics of SLD， and comprehensively reviews the research progress of quantum well， quantum dot near-infrared SLD and quantum cascade mid-infrared SLD. Among them， the novel active structure of InP based quantum dash， hybrid quantum well/ quantum dots and hybrid quantum well-dots， as well as quantum dot doping and selective area intermixing are introduced in detail. Finally， the application prospects of SLD are outlined， and the potential research directions and technological application trends of SLD are discussed.Keywords：superluminescent diode;quantum well;quantum dot;quantum cascade;optical coherence tomography
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Published：2023-05-26 - Abstract：Eu（DBM）3Phen was firstly encapsulated into carboxylated polystyrene microspheres by the encapsulation method， and then the lanthanide luminescence center Tb3+ was introduced by coordination to obtain the fluorescent polystyrene microsphere hybrid probe Tb-PS@Eu（DBM）3Phen with dual emission centers. The results indicated that Tb-PS@Eu（DBM）3Phen has excellent stability， dispersibility and fluorescence properties. In addition， by further investigating the fluorescence sensing properties of the probe molecule on 2，6-pyridinedicarboxylic acid （DPA）， it was found that Tb-PS@Eu（DBM）3Phen could produce a significant enhancement with the present of DPA， which might be due to the coordination of terbium ions on the surface of DPA and polystyrene microspheres， which in turn affected the energy transfer process between the ligand-rare earths， resulting in Tb-PS@Eu（DBM）3Phen's fluorescence enhancement. Meanwhile， Tb-PS@Eu（DBM）3Phen has strong selectivity and anti-interference ability for DPA， which is expected to be used as a potential fluorescent probe for the recognition of DPA.Keywords：lanthanide complexes;fluorescent microspheres;DPA;ratiometric fluorescent sensing
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Published：2023-05-26 - Abstract：Efficient and thermally robust glass ceramic phosphors combined both the merits of phosphors and matrix have received growing interests in the white-LED and laser driven lighting. Here， the YAG： Ce glass ceramics were prepared by an energy saving and fast selective laser sintering with suitable parameters （laser power： 24 W， scanning speed： 135 mm/s， scanning intervals： 9 μm）. The results show that selective laser sintered YAG： Ce glass ceramic after heat treatment （630℃， 1 h） exhibits the typical Ce3+ 4f→5d broadband excitations centered at 340 and 455 nm and 5d→4f emission centered at 570 nm and its photoluminescence quantum yield is up to 82%. Moreover， combining with a 450 nm LED chip （3.11 V，0.30 A） directly， the obtained performances including the luminous flux （92 lm）， luminous efficiency （98 lm/W）， color rendering index （69）， correlated color temperature （5001 K）， and chromaticity coordinates （0.34， 0.35） are close to other YAG： Ce glass ceramic reported. All of those validate the suitability of selective laser sintering for preparation of glass ceramics.Keywords：glass ceramic phosphor;Ce3+ doped;selective laser sintering;white light-emitting diodes
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Published：2023-05-26 - Abstract：Lanthanide Eu3+-doped metal-organic backbone material Eu/ZIF-67 was prepared by a one-step hydrothermal method with a novel pleated sphere structure. A dual-emission fluorescent hybrid material Eu/ZIF-67@ZnO QDs with a zeolite imidazolium ester backbone was obtained by loading ZnO quantum dots onto the surface of Eu/ZIF-67 via coordination bonding. The structure， morphology and fluorescence sensing properties of the material were characterized in detail. Furthermore， the fluorescent material was found to display the dual fluorescence emission of ZnO quantum dots and lanthanide red europium ions. The fluorescence sensing performance of Eu/ZIF-67@ZnO QDs to tannic acid was further investigated， and the results indicated that tannic acid can effectively burst the characteristic fluorescence emission of Eu/ZIF-67@ZnO QDs at ZnO QDs with a detection limit of 0.0299 µM. Meanwhile， Eu/ZIF-67@ZnO QDs have the fluorescence response to tannic acid with anti-interference ability， which can be used as a cost-effective fluorescence sensor to specifically identify tannic acid.Keywords：metal organic skeleton;quantum dots;dual-emission probes;tannic acid;fluorescent detection
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Published：2023-05-26 - Abstract：Due to their unique structures and excellent optoelectronic properties， two-dimensional （2D） materials and their heterostructures are promising materials for the next generation optoelectronic technology. The dynamic properties of photocarriers have an important influence on the optoelectronic properties of these materials. This review article discusses the research progress in recent years on the photocarrier dynamics in these materials. In the time domain， transient absorption measurements of carrier thermalization， energy relaxation， exciton formation， exciton-exciton annihilation， and exciton recombination in 2D materials are discussed. In the spatial domain， high-spatial-resolution transient absorption microscopy studies of photocarrier in-plane transport properties are introduced. Furthermore， interlayer charge and energy transfer in 2D heterostructures are discussed.Keywords：two-dimensional material;transient absorption;carrier dynamics;ultrafast laser
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Published：2023-05-26 - Abstract：One-dimensional photonic crystals （1DPCs） are artificially constructed periodic optical dielectric structures. 1DPCs can modulate the luminescent material mainly by defect mode modulation and band-edge mode modulation. 1DPC band-edge mode with a large density of photonic states can effectively modulate the luminescent properties of the luminescent material. In this paper， the fluorescence emission of colloidal quantum dot （CQD） materials coated on the surface of 1DPC is studied. By using different QD materials， different surface film thicknesses， and different angles for fluorescence detection， luminescence characteristics of the samples have been studied. The results show that 1DPC band edge mode can effectively regulate the luminescence characteristics of CQD films located in the surface layer， effectively enhance the fluorescence emission intensity and narrow the emission linewidth. CQD materials controlled by 1DPC band edge mode have faster fluorescence radiation transition rate. The influence of 1DPC on the luminescent properties of CQD materials is helpful to optimize the design of the device structure， so as to greatly improve the performance of the luminescent devices.Keywords：Band edge mode;colloidal quantum dots;photoluminescence;angular distribution;one-dimensional photonic crystal
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Published：2023-05-26 - Abstract：Passivation of the lower surface （buried interface） of perovskite using organic small molecules is an effective strategy to suppress carrier recombination. This work focus on passivation of the buried interface of perovskite by pre-coating the passivation material of phenylethylamine （PEA） before depositing the perovskite film. After passivation treatment， the grain size and morphology of the perovskite crystalline film did not change. After passivation， there is a slight red-shift in the absorption edge and emission wavelength of perovskite， and a slight increase in the energy level of highest occupied molecular orbital； “Pb” binding energy moves to a higher level， while “N” binding energy moves to a lower level. These results confirm that the “N” atoms on PEA molecules can interact with the dangling “Pb” at the buried interface of perovskite. The results showed a significant reduction of residual PbI2 in perovskite， indicating that PEA molecules reacted with PbI2 to form a certain complex. Furthermore， the solar cells were fabricated to investigate the passivation effect and the results showed that the open-circuit voltage （Voc）， short-circuit current density （Jsc）， fill factor （FF） and power conversion Efficiency （PCE） of the control perovskite solar cells were 1.041 V， 21.29 mA/cm2， 74.09%， and 16.41%， which for PEA-passivated perovskite solar cells， increased to 1.102 V， 22.44 mA/cm2， 79.28%， and 19.6%， respectively. The significant improvement of device performance induced by passivation of perovskite buried-interface defects is mainly due to the reduction of carrier recombination which mainly attributed to 1） passivation of the defects caused by unsaturated-coordination “Pb”； 2） passivation of the defects caused by the complex phases of PbI2 microcrystals； 3） improvement of the charge transfer rate between perovskite and the hole-transporting layer. The stability of passivated perovskite solar cells is significantly enhanced. This simple and effective buried-interface passivation strategy can be applied to the fabrication of large-scale perovskite solar cells in the future.Keywords：perovskite;buried interface;phenethylamine;passivation;solar cells
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Published：2023-05-26 - Abstract：Due to the quantum confinement effect， self-assembled semiconductor single quantum dots exhibit atom-like discrete energy levels enabling highly indistinguishable， high brightness and high purity single photon emission， where multiple exciton states in quantum dots can generate photons with different polarizations. The optical micro-nano structure is an effective means to modulate the luminescent properties of single quantum dots. When a single quantum dot is weakly coupled to an optical micro-cavity， the Purcell effect will greatly improve the performances of the quantum dot as a single photon source or entangled photon-pair source. Meanwhile， the strongly coupled system of quantum dots and optical micro-cavities can be used as quantum nodes in the quantum photonic network or to study the nonlinear optics at the single photon level. Utilizing the coupling of quantum dots and optical waveguides can realize coherent conversion between solid-state quantum bits and flying photonic bits along with efficient information processing and transmission for building a reliable on-chip photonic network. In addition， a single quantum dot has manipulable spin states， which can work as carriers for quantum bits. Considering the convenience of combining the fabrication process of quantum dot devices with mature semiconductor technology， device designs with quantum dots allow good scalability and integration potential.Keywords：self-assembled semiconductor quantum dots;excitons;spins;optical microcavities;optical waveguides
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Published：2023-05-26 - Abstract：A series of CsLa（WO4）2 phosphors with different doping concentrations of Pr3+ were prepared by the high temperature solid-state method. X-ray diffraction （XRD）， diffuse reflectance spectra， excitation spectra， emission spectra and fluorescence decay curves were analyzed. The concentration and temperature-dependent luminescent properties were investigated. The fluorescence temperature sensing parameters were calculated based on the fluorescence intensity ratio （FIR） technique. The optimal doping concentrations of Pr3+ for the emissions from 3P0 and 1D2 levels in CsLa（WO4）2 were found to be 0.03 and 0.01， respectively， and it was confirmed that concentration quenching was caused by the dipole-dipole interactions. The emission trends of 3P0 and 1D2 levels were different with temperature， mainly due to the effects of the cross-over process to Pr3+-W6+ intervalence charge transfer （IVCT） state， cross relaxation process and multiphonon relaxation process. The different concentration and temperature- dependent characteristics of the emissions from 3P0 and 1D2 levels enabled tunable color emissions. According to the fluorescence intensity ratio （FIR） of 3P1 → 3H5 / 3P0 → 3H4 thermally coupled energy levels and 1D2 → 3H4 / 3P0 → 3H4 non-thermally coupled energy levels， the calculated relative sensitivities were 586.01/T2 K-1 and 1071.78/T2 K-1， respectively， indicating the potential application of this material in temperature sensing.Keywords：Pr3+;CsLa（WO4）2;photoluminescence;temperature sensing;fluorescence intensity ratio （FIR）
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Published：2023-05-26 - Abstract：Flexible reflective electrochromic devices have broad application prospects in e-paper displays， camouflage， and intelligent color-changing surfaces， but there are still problems such as poor flexibility， low optical contrast， and poor stability. Indium-free reflective electrochromic electrodes with Cr/Ag/WO3 （CAW） structure have been prepared by electron beam evaporation on glass and flexible PET substrates. CAW films have high reflectance and low surface resistance. The average visible light reflectance is up to 89.2%， and the surface resistance is only 1.2 Ω/□. In terms of electrochromic properties， CAW films show fast colored and bleached response times of 9.3 s and 2.0 s， high optical contrast of up to 83.0% （564 nm）， wide range of reflective color modulation （>40 nm）， and excellent electrochemical cycling stability （>4500 cycles）. In addition， CAW films have good substrate compatibility. We prepared flexible CAW films and assembled patterned flexible electrochromic devices. The electrical properties of the flexible film remain almost unchanged after 2000 consecutive bends and the optical contrast reach 83.2% at 574 nm. The devices realize rich reflected color dynamic regulation under different voltages. These results will provide simple and effective guidance for the construction of high-performance flexible reflective electrochromic devices， and have certain application potential in the field of new display technology.Keywords：electrochromic;WO3;Indium-free;flexibility;reflection
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Published：2023-05-16 - Abstract：As one of the most important schemes to realize the stretchable displays， the stretchable light-emitting device array based on the island-bridge structure has attracted much attention. In this paper， we introduce the research progress of stretchable light-emitting device array based on island-bridge structure in the past ten years， and summarize the performance and characteristics of each device. Focusing on the key issues such as stretchability， mechanical stability and display quality of the device， the shape design and material selection scheme of the stretchable wires （interconnect bridge） between luminous units are introduced. The common optimization strategy of high-density pixel integration， tensile strain distribution and the solution for decreased pixel density due to the increase of stretchability are summarized. At present， the research of the stretchable luminescent display array based on island-bridge structure is still in its initial stage. The design， fabrication and realization of high-performance devices still face many challenges. This review aims to make some contribution to advancing the development of stretchable displays by summarizing current research.Keywords：light-emitting device;stretchable;island-bridge structure
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Published：2023-05-16 - Abstract：Organic red emitters have attracted significant research attention owing to their promising applications in panchromatic display， biological imaging， and fluorescent probes. Herein， a fluorescent compound DBPAP was developed by introducing electron-donating group diphenylamine derivative at the positions of 3 and 6， and electron-withdrawing group pyridine at the positions of 11 and 12 of dibenzophenazine core. Its chemical structure was characterized and confirmed by elemental analysis， nuclear magnetic resonance spectroscopy and mass spectroscopy. Spectroscopic results showed that the addition of the poor solvent water to the tetrahydrofuran solution of DBPAP caused obvious aggregation-induced emission （AIE） phenomenon. Based on its efficient red emission in solid state， LED devices based on DBPAP doped PMMA was fabricated. The devices exhibited a red emission at 644 nm with Commission Internationale de L’Éclairage coordinates of （0.58， 0.35）， and a maximum brightness of 1616 cd m-2 at a 3.8 V work voltage. This work provides a promising strategy for developing solid-state red emissive organics.Keywords：Organic red emitters;dibenzophenazine;donor-acceptor;aggregation-induced emission;red LED
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Published：2023-05-16 - Abstract：Transparent display is one of the development directions for future displays， with huge application potential in fields such as smart windows， wearable electronic products， virtual reality technology， and touch screens. With the emergence of new luminescent materials such as organic， quantum dots， and perovskites， the brightness， efficiency， and stability of light-emitting diodes have rapidly developed. However， achieving high-performance transparent light-emitting diodes with symmetrical luminescence on both sides remains a challenging task. This article starts from three new luminescent materials， namely organics， quantum dots， and perovskites， and summarizes specific schemes for achieving transparency using different transparent electrodes. It summarizes the characteristics， advantages， and disadvantages of various transparent electrodes， and finally prospects the development of transparent displays.Keywords：transparent display;light-emitting diodes;transparent electrodes;luminescent materials
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Published：2023-05-16 - Abstract：Thermally activated delayed fluorescence （TADF） materials with distinct electron donor and acceptor （D-A） segments can achieve theoretically 100% internal quantum efficiencies via the reverse intersystem crossing （RISC） process， thus receiving tremendous attention in lighting， display， and biomedical fields. Generally， D-A systems with intramolecular charge transfer （ICT） characteristics minimize singlet-triplet energy gap （ΔES-T） by having molecular conformations twisted， so that the RISC process takes place rapidly. Once the dihedral angle of D-A segments in the excited molecular conformation is further twisted， approaching 90 degrees， ΔES-T will be smaller and the TADF characteristics will be also enhanced. However， conformational changes of excited states， ICT process and TADF emission are often influenced by solvent effect， which poses a challenge for understanding luminescence mechanism of TADF molecules. This review mainly summarizes the recent progresses in the influence of solvation on the delayed fluorescence made by our groups. As a result， it is shown that strongly polar solvents lead to an increase in non-radiative relaxation that is averse to TADF， as well as alteration of solvent viscosities affects the excited state conformational relaxation， resulting in the enhancement or weakening of DF. These results are valuable for understanding the role of solvation in conformational relaxation and DF emission， and provide guidance for the design and synthesis of TADF molecules.Keywords：organic donor-receptor systems;thermal activated delayed fluorescence;solvation;intramolecular charge transfer
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Published：2023-05-16 - Abstract：Improving the upconversion luminescence efficiency is the key to promoting the practical application of upconversion luminescent materials. In the NaErF4@NaYF4 system， the inert NaYF4 shell can inhibit the concentration quenching under high Er3+ doping， and the upconversion luminescence is mainly from the energy transfer upconversion of Er3+-Er3+. In this paper， Er3+ and Yb3+ partition doped NaErF4@NaYbF4@NaYF4 core-shell nanoparticles were prepared by the coprecipitation method， and the energy transfer and back energy transfer processes between Er3+-Yb3+-Er3+ was studied. Since the 808 nm can only excite Er3+ but not Yb3+， under 808 nm excitation， Er3+ harvests the pumping energy and transfers it to Yb3+ and subsequently back to Er3+ due to the protection offered by NaYF4 inert outer shell， which finally enhances the upconversion luminescence of Er3+. When the doping concentration of Yb3+ in the intermediate layer is 100%， the maximum enhancement multiple is 24.9 and 9.79 for green and red upconversion， respectively.Keywords：rare earth nanoparticles;upconversion luminescence;back energy transfer;β-NaErF4
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Published：2023-05-16 - Abstract：Hexagonal phase NaYF4：20%Yb， 2%Er@NaYF4@NaYbF4：0.5%Tm@NaYF4 lanthanide-doped nanoparticles with the core@multishell structure were synthesized by solvothermal method. The upconversion luminescence （UCL） properties of the materials at temperature from 10 K to 295 K were studied under 980 nm excitation. Green and red UCL from Er3+ and blue UCL from Tm3+ were observed in the visible light range. The luminescence intensity of green UCL first increased and then decreased， while the luminescence intensity of blue light showed a thermal attenuation trend with the temperature increase. The method of temperature-dependent luminescence intensity ratio （LIR） can be used in accurate temperature measurement， and the relative sensitivity is up to 3.2%·K-1. With various thicknesses of the outer luminescent shell， the different tendencies of LIR can be realized， which can be applied to cryogenic field anticounterfeiting.Keywords：rare-earth nanoparticles;LIR thermometry;upconversion luminescence;cryogenic field;anticounterfeiting
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Published：2023-05-16 - Abstract：Bloch surface wave （BSW） is an electromagnetic mode in which the light field is localized in the surface layer and propagates along the surface layer of the photonic crystal. In this paper， a PS：C545T organic luminescence layer was prepared on a one-dimensional photonic crystal， and the fluorescence of the exciton of organic C545T molecules coupled into the BSW mode was observed. By studying the performance of the output light emission of the sample through the hemispherical lens coupling， the different characteristics of the conventional luminescence and the BSW mode luminescence of C545T are analyzed and compared. The results show that the coupled BSW mode output a ring light spot， which has the characteristics of narrow spatial distribution， linear polarization and adjustable spectral with angle， and is obviously separated from the light spot of conventional radiation mode. The radiation transition rate of luminous films on one-dimensional photonic crystals is anisotropic， and the BSW mode fluorescence has a faster radiation transition rate. The above luminescence characteristics of BSW mode can be utilized to develop polarized light-emitting devices with certain directivity.Keywords：Bloch surface wave;organic materials;polarization;angular distribution;one-dimensional photonic crystal
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Published：2023-05-16 - Abstract：The new perovskite solar cells based on ABX3 crystal structure material have the advantages of high photoelectric conversion efficiency， solution processability， and low temperature process compatibility. At the same time， semitransparent perovskite solar cells prepared by using the advantages of simple synthesis methods， adjustable band gap and controllable film thickness and transmittance of perovskite materials have brought new opportunities for the development of thin film photovoltaics. Semitransparent solar cells have broad application prospects in building-integrated photovoltaics and tandem photovoltaics. Developing efficient and highly stable semitransparent perovskite solar cells has become a research focus in the photovoltaic field. This article systematically reviews the technical strategies for selecting functional layer （perovskite photoactive layer，charge transport layer，and electrode） materials， regulating optical properties， optimizing electrical properties， and regulating the preparation processes of semitransparent perovskite solar cells. At the same time， some prospects for the future development of semitransparent perovskite solar cells are presented.Keywords：semitransparent;building photovoltaic integration;tandem;perovskite solar cells
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Published：2023-05-16
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