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Issue 10 ， 2022
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Quantum-dot Light-emitting Diodes Based on Inorganic Charge-generation Layer Enhanced Publication
Abstract：Quantum-dot light-emitting diodes（QLEDs）are fabricated by employing an inorganic charge-generation layer（CGL） consisting of WO3/ZnO instead of commonly used ZnO electron-transport layer. The performance of CGL based QLED is increased by around 30% compared with the device with ZnO as the electron-transport layer， which is attributed to the electrical field-dependent charge injection of CGL， resulting in more balanced charge injection and efficient exciton formation. Moreover， the emission quenching processes induced by charges are also reduced. The working mechanism of CGL based QLEDs is unraveled by transient electroluminescence spectrum and capacitance measurements. We find that the CGL can act as a charge reservoir， which is the origin of electroluminescence overshoot at the rising edge of transient electroluminescence response. Additionally， the shelf lifetime of CGL-QLEDs is identical with or even better than the normal ZnO based devices. Considering the charge injection of CGL is independent on the work function of electrodes， we believe the device structure proposed in this work has great potential to improve device stability and yield.Keywords：quantum-dot light-emitting diodes;charge-generation layer;overshoot;charge storage- 759
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Published：2022-11-04
Cover Story
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Research Progress Towards Perovskite Electrical Driven Lasers Enhanced Publication
Abstract：Solution-processed perovskites， having excellent optical and electrical properties， can serve as a kind of promising electrically driven laser gain medium. In recent years， progresses towards electrically driven lasers based on perovskite materials have been made. For instance， a series of room-temperature continuous-wave optically-pumped perovskite lasers along with a few high-current perovskite light emitting diodes（LEDs） have been reported. This paper takes this topic as the review subject. Firstly， the advantages of perovskite materials for developing electrical driven lasers are introduced. Then， the two major constraints towards electrical driven perovskite lasers at the present stage， including high non-radiative recombination loss and serious thermal effect， are introduced， and some strategies to break through these constraints are given. Subsequently， this paper gives supplementary means such as balancing the charge injection， reducing optical loss， and promoting population inversion， which have effectively promoted the development of perovskite electrical pumped laser research. This paper also introduces the recent progresses of surface plasmon polariton lasers， exciton polariton lasers， etc.， based on perovskite materials， which possess the potential to reduce the laser thresholds， as alternatives for realizing electrical driven perovskite lasers. Finally， the full text is summarized， and the future research towards electrical driven perovskite lasers is prospected.Keywords：perovskite;laser;electrical driven;lasing threshold- 681
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Published：2022-11-04
Invited Review
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First-principles Calculations on Luminescent Properties of Rare-earth（Ce3+/Eu2+） Ions and Point Defects Enhanced Publication
Abstract：Recent years have witnessed the development of first-principles approaches to study luminescent properties of rare-earth ions and point defects in inorganic phosphors. In this article， we briefly describe the progresses made by the authors and co-workers in this field. Firstly， the first-principles-based approaches to rare-earth luminescent materials are introduced. These include density functional theory calculations of point defects based on the supercell model and wavefunction-based multi-configuration ab initio calculations of excited states. Then， the applications of the methods to some Ce3+- and Eu2+-doped phosphors are elaborated from two aspects， i.e.， thermodynamic stabilities and luminescence mechanisms of point defects， and assignment of 4f→5d excitation spectra of the doped rare-earth ions. Finally， chances and challenges in the field of first-principles calculations on rare-earth luminescent materials are briefly discussed.Keywords：rare-earth ions;point defects;luminescence mechanisms;density functional theory;multi-configuration interaction- 1554
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Published：2022-11-04
Views on Basic Knowledge of Luminescence
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Progress in Research and Application of New Optical Functional Rare Earth Complexes Enhanced Publication
Abstract：The rare earth complexes have attracted wide attention and aroused intensive research due to their unique photophysical properties， which endow them important application prospects in the fields of light-emitting devices and fluorescent probes， etc. In this paper， the photophysical properties and luminescence mechanism of the rare earth complexes were sorted out， and the research progress of the photofunctional rare earth complexes in recent years was summarized， particularly in the fields of organic light-emitting diodes and fluorescent probes. Finally， the potential application and further research prospects of the rare earth complexes were proposed.Keywords：rare earth complexes;photophysical properties;Photofunctional materials;fluorescent probes;Light-emitting devices- 324
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Research Progress in Preparation of Fluorescent Nanomaterials by Microfluidic Technique Enhanced Publication
Abstract：Fluorescent nanomaterials have been widely used in diverse fields like sensing， bio-imaging， ions detection， owing to their unique optical properties. Microfluidic is an effective technique that allows the precise control and manipulation of fluids in microscale dimension. In recent years， it has exhibited important practical values in organic synthesis， fluorescent materials preparation， cell detection， and drug screening. This work focuses on the microfluidic synthesis of fluorescent nanomaterials， and reviews recent advances in this field. Firstly， according to the characteristic structure， different types of microfluidic reactors along with their working principles are elaborated， including chip-based microreactors， tubular microreactors， and centrifugal microreactors. Afterwards， representative examples of fluorescent nanomaterials are summarized， such as semiconductor nanoparticles， carbon dots， perovskite nanoparticles， rare earth nanomaterials， metal and metal oxide composites. Finally， the existed challenges and future development of this field are prospected.Keywords：microfluidic technique;continuous flow synthesis;microreactor;fluorescent nanomaterials- 699
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Preparation and Properties of A Novel Yellow Long Persistent Luminescence Material
γ -SrGa2O4∶Bi3+ Enhanced PublicationAbstract：Deep traps in long persistent luminescence（LPL） materials have excellent energy storage and release properties， and thus have great application advantages in optical information storage. In this paper， a novel yellow long afterglow material γ-SrGa2O4∶Bi3+ was synthesized by high-temperature solid-phase method， and its emission spectrum is a broadband emission centered at 565 nm in the range of 400-800 nm， which is attributed to the 3P1→1S0 transitions of Bi3+. The bright yellow LPL of the γ-SrGa2O4∶Bi3+ sample was observed after UV lamp irradiation. The analysis of the thermoluminescence（TL） curve indicates that there are three main traps in γ-SrGa2O4∶Bi3+ with the depths of 0.678， 0.838， 0.978 eV， respectively. The shallow trap with a depth of 0.678 eV is the main reason for the LPL phenomenon of the material， while the intensity of the TL peak corresponding to the deep trap with a depth of 0.838 eV only decreases by 18.6% after 12 h， which indicates the slow electron release in the deep trap. Based on the deep trap properties of the material， the letter patterns were designed and experimented for optical information storage， and the results showed that the material has potential applications in information storage.Keywords：information storage;γ-SrGa2O4∶Bi3+;yellow long persistent luminescence;trap- 342
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Up-conversion Luminescence and Temperature Sensing Properties of La2
A TiO6（A =Mg, Zn） Phosphor Enhanced PublicationAbstract：The up-conversion performance of Er3+ strongly depends on local position symmetry distortion. In this study， the series of La2（1-x）ZnwMg（1-w）TiO6∶xEr3+（x=0.06； w=0， 0.3， 0.5， 0.7， 1.0） were prepared by solid state reaction at high temperature. According to XRD refinement， the coordination environment of La2MgTiO6 crystal was changed by Zn2+ doping， and the crystal phase changed from Pbnm to P21/n. Besides， the up-conversion fluorescence intensity of the sample changed with the change of Er3+ ion concentration excited by a 980 nm laser， and the concentration of Er3+ was x=0.06 when the up-conversion fluorescence intensity was the highest. Based on the fluorescence intensity ratio technique， the temperature sensing properties of the samples La2（1-x）ZnwMg（1-w）TiO6∶xEr3+（x=0.06； w=0， 0.3， 0.5， 0.7， 1.0） were studied from 303 K to 583 K. The results show that the sensitivity changes with the concentration ratio of Mg2+ and Zn2+ and reaches the maximum absolute sensitivity of 0.90%·K-1 when w=1.0， which indicates that the doping of Zn2+ increases the sensitivity of La2MgTiO6.Keywords：Er3+ doping;fluorescent powder;fluorescence properties;temperature sensing- 269
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Down-conversion Luminescence and Temperature Sensing Characters of KBaGd（MoO4）3∶Er3+ Under NUV Excitation
Abstract：In recent years， Er3+ doped inorganic materials have been widely investigated for temperature sensing materials. In this paper， Er3+ doped KBaGd（MoO4）3 phosphor was prepared by sol-gel method. Its luminescence and temperature sensing properties were studied by room temperature excitation and emission spectra， luminescence decay curves and temperature-dependent emission spectra. The luminescence spectra show that KBaGd（MoO4）3∶Er3+ possesses efficient absorption at 380 nm， which is attributed to the 4I15/2→4G11/2 transition of Er3+ ions. Under NUV excitation， KBaGd⁃（MoO4）3∶Er3+ exhibits two bright green emission between 520-570 nm. Due to the dipole-diploe interaction effect， the concentration quenching begins as the doping concentration of Er3+ is beyond 8%. Based on the fluorescence intensity ratio （FIR） model， the calculated absolute sensitivity of KBaGd（MoO4）3∶Er3+ is larger than most of the reported temperature sensing materials of the same kind， so it may has a better prospect in the field of temperature sensing. Ultimately， the photoelectric parameters of the designed LED with KBaGd（MoO4）3∶Er3+ were recorded and its potential application in lighting field was objectively evaluated.Keywords：optical temperature measurement;concentration quenching;fluorescence intensity ratio;temperature sensing- 246
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Published：2022-11-04
Synthesis and Properties of Materials
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Perovskite Light Emitting Diodes Using Covalent Organic Polymers as Hole Injection Layers Enhanced Publication
Abstract：Halide perovskite（ABX3） quantum dots and their light-emitting devices have the characteristics of high color purity， high luminous efficiency， and tunability in the visible light range. In recent years， they have shown great potential in lighting， display and other fields. However， the stability of perovskite quantum dot light-emitting diodes（PeQLEDs） is becoming the biggest obstacle to its commercial application. In addition to the stability of the perovskite light-emitting layer itself， the water-oxygen stability of the transport layer cannot be ignored. This work introduces a novel PeQLEDs that utilize an azole-based monomer-synthesized organic covalent polymer material（COP-N） instead of conventional PEDOT∶PSS as the hole injection layer material. We found that COP-N material has intrinsic water-oxygen stability， as well as a smaller hole injection barrier with PVK. These characteristics enable the COP-N-based PeQLED to achieve nearly twice the stability improvement while achieving better EQE than PEDO∶PSS. We believe that this organic covalent polymer material is expected to be a new type of hole injection material to achieve efficient and stable perovskite electroluminescent device， and promote the development of PeLEDs.Keywords：Covalent organic polymers;hole injection layer;perovskite quantum dots;light-emitting diodes- 425
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Iridium Phosphorescent Complexes Based on Modified Phenylquinoline Ligand and Their High-efficiency Pure Red Organic Electroluminescent Device Enhanced Publication
Abstract：Two iridium phosphorescent complexes were synthesized by using the modified 2，4-2R-phenyl-4-methylquinoline as the main ligands. Methyl or methoxy was introduced in the positions 2 and 4 with small steric hindrance of phenyl. Their compositions and chemical structures of the complexes were characterized by elemental analysis， nuclear magnetic resonance spectroscopy and single crystal X-ray diffraction. The （2，4-2Me-mpq）2Ir（acac） and （2，4-2MeO-mpq）2Ir（acac） with the photoluminescence quantum yields of 75% and 80% exhibit maximum emission peaks at 610 nm and 580 nm， respectively. The HOMO-LUMO energy levels difference of the two complexes are 2.04 eV and 2.19 eV， respectively. Using （2，4-2Me-mpq）2Ir（acac） as the guest material， the high-efficiency pure red OLED with structure ITO/TAPC（30 nm）/CBP∶（2，4-2Me-mpq）2Ir（acac）（30 nm）∶x%/TPBi（30 nm）/Liq（2 nm）/Al was prepared with different doping concentrations. At the optimal doping concentration of 10%， the device based on （2，4-2Me-mpq）2Ir（acac） exhibited a red emission at 607 nm with CIE（0.63， 0.37）， a luminance of 25 980 cd/m2， a maximum current efficiency of 23.11 cd/A and a maximum external quantum efficiency（EQE） of 20.28%， respectively.Keywords：iridium complexes;phosphorescent materials;high efficiency;red OLED;luminescent property- 213
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Photoelectric Characteristics of Non-electric Contact GaN-based Micro-LED Device Enhanced Publication
Abstract：In this paper， non-electrical contact（NEC） GaN-based Micro-LED devices were prepared by metal organic chemical vapor deposition（MOCVD） and atomic layer deposition（ALD） because a series of problems would emerge， including mass transfer， bonding， and high-quality contact between chips and driving electrodes as the LED chip size is further decreased. We investigated the photoelectric characteristics of NEC Micro-LED devices， such as the current-voltage（I-V）， luminance-frequency（L-F）， luminescence delay and impedance-frequency（I-F） characteristics， and the working mechanism of the device is also analyzed. These experimental results indicate that the current of the NEC Micro-LED device increases with the increase of the frequency and I-V curves have linear relationships under the role of the alternating-current drive. At the driving signal of 20Vpp， the luminances of the NEC Micro-LED device first increase and then fall with the gradual increases of the frequencies. When the frequency is 25 MHz， the luminance of NEC Micro-LED device reaches to be the maximum. Moreover， the luminescence peak lags behind the current peak， indicating that the luminescence of the device is delayed. Besides， the equivalent impedance of the NEC Micro-LED device decreases and finally tends to be stable with the increases of the frequencies and the device shows the negative capacitance phenomenon around the frequency of 53 MHz.Keywords：Micro-LED device;GaN;Non-electrical contact;Alternating-current drive;photoelectric characteristics- 295
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Brillouin Dual-wavelength Narrow-linewidth Fiber Laser and Its Application in Frequency-swept Microwave-signal Generation Enhanced Publication
Abstract：A Brillouin dual-wavelength narrow-linewidth fiber laser with a high-nonlinear-fiber（HNLF） is proposed and demonstrated， and the frequency-swept microwave-signal generation with the fiber laser is studied in detail. A narrow-linewidth fiber laser source as the seed laser is amplified by a high-power erbium-doped fiber amplifier. The amplified laser is then filtered to remove the strong amplified spontaneous emission noise by a high-reflection fiber Bragg grating（FBG） with the reflecting center wavelength close to the seed fiber laser’s output wavelength， and is subsequently used as the pump laser of stimulated Brillouin scattering（SBS） of the HNLF. The length of HNLF is 3.0 m long， which can provide a low SBS pump threshold. The cavity length of the Brillouin laser is 6.6 m， corresponding to a longitudinal-mode spacing of ~31 MHz， which can ensure the single-longitudinal-mode operation of the Brillouin laser. When the input power of HNLF is 1.8 W， the linewidth of the Brillouin laser measured is 622.50 Hz， and the dual-wavelength lasing output with a signal-to-noise ratio（OSNR） of >77 dB is obtained by combining the residual pump laser and the Brillouin laser. By beating the dual-wavelength laser output， a microwave signal with a frequency around 9.4 GHz is obtained. Using a step-motor based fiber stretcher to introduce strain modulation to the HNLF， the frequency-swept microwave signal with a sweep-range of 289.7 MHz and a sweep-rate of 10 Hz is realized. The proposed fiber laser has potential applications in optical/wireless communication， fiber sensing， and microwave photonics.Keywords：stimulated Brillouin scattering;Dual-wavelength fiber laser;Frequency-swept microwave signal- 231
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Published：2022-11-04
Device Fabrication and Physics
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High-performance ZnS∶Cu Based Mechanoluminescent Elastomers and Their Applications in Visually Interactive Fabrics Enhanced Publication
Abstract：With the rapid development of flexible wearable electronics， the demand for intelligent wearable devices has remarkably increased. Smart luminescent clothing with the ability of visual interaction has attracted wide attention due to its versatile functions. Elastico-mechanoluminescent materials such as ZnS∶Cu mechanoluminescent elastomers have potential applications in smart luminescent cloths/garments because of their repeatable force-to-light visualized sensing capabilities. In this work， we increased the stress transfer sites in ZnS∶Cu mechanoluminescent elastomers through tunning the network structure of the elastic polymer matrix and the doping of Al2O3 nanoparticles， thus improved the luminescence intensity of the mechanoluminescent elastomer. The continuous and patterned preparation of mechanoluminescent textile has also been achieved through extrusion coating， 3D printing， and screen printing mechanoluminescent elastomers on traditional textiles. The sensitivity and wearing comfort of the luminescent woven textiles have therefore been improved， which provides potential value for this mechanoluminescent elastomers in applications including wearable sensing， health monitoring， traffic warning， etc.Keywords：mechanoluminescence;Elastomers;nanoparticles;Visualized mechanical sensing;Luminescent textiles- 1042
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Published：2022-11-04
Luminescence Industry and Technology Frontier
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A Novel Near-infrared Fluorescent Probe for Detection of Aβ40 Aggregates Enhanced Publication
Abstract：β-Amyloid（Aβ） senile plaques are one of the most important pathological markers of Alzheimer's disease（AD）， which plays a quite important role in the pathogenesis of AD. In the early stage of AD， Aβ40 aggregates are the most predominant and abundant. Therefore， the detection of Aβ40 aggregates is conducive to the early diagnosis of AD. In this work， a small molecule fluorescent probe C-1 with a D-π-A structure was designed and synthesized for the fluorescence detection of Aβ40 aggregates. The probe C-1 displays superior fluorescence properties（λem=640 nm） and shows remarkable binding capacity for Aβ40 aggregates（Kd=3.072 μmol/L）， enabling the specific detection of Aβ40 aggregates in solution. In addition， the probe has series of advantages， including simple synthesis， low cost， high sensitivity and fast response.Keywords：fluorescent probe;Aβ;Alzheimer's disease;near-infrared （NIR）- 167
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Utilizing NIR AIE Luminogen Based Magnetic Nanoparticle for Light-enhanced Bacterial Killing Enhanced Publication
Abstract：NIR photosensitizers（PSs） could significantly improve the efficacy of photodynamic therapy due to the long-wavelength favorability for deeper tissue penetration and lower biological damage. In this paper， a deep-red emissive AIEgens 5，6-bis（4′-（diphenylamino）-［1，1′-biphenyl］-4-yl） pyrazine-2，3-dicarbonitrile（DCDPP-2TPA） was synthesized for light-enhanced bacterial killing. Due to the advantage of AIEgens which are ultra-emissive in the aggregate states or solid states， DCDPP-2TPA was incorporated into magnetic nanoparticle to increase aggregation enhanced reactive oxygen species（ROS） generation property as well as magnetic separation convenience. The magnetic particles were studied by scanning electron microscope（SEM）， transmission electron microscope（TEM）， X-ray diffraction（XRD）， and fluorescence spectrophotometer， etc. The capacity of bacterial killing was exhibited on E.coli and S. aureus under light irradiation. Due to the aggregation enhanced ROS generation， the viability of E.coli and S. aureus treated with DCDPP-2TPA based magnetic nanoparticle with room light illumination for 30 min are 7.5% and 9.0%， which was superior to DCDPP-2TPA（10% and 14% respectively）. The significant superiority of magnetic nanoparticles is that it can be withdrawn easily and continuously used for bacteria killing by applying light to induce ROS generation.Keywords：AIE Luminogen;Magnetic nanoparticle;Bacterial Killing- 145
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Synthesis of Oxadiazolidone Fluorescent Probes Based on Quinoline Group and Recognition of Fe3+ Ions Enhanced Publication
Abstract：Three quinolinyl hydrazines 1-3 were prepared from 8-aminoquinoline by diazotization， reduction and acylation reactions， and three oxadiazoles fluorescent probes 4-6 for Fe3+ were prepared by cyclization reaction with triphosgene. The structures of the six new compounds were characterized by IR， NMR and MS. At the same time， the thermal and optical properties of these compounds were tested and analyzed by thermogravimetry and fluorescence. The results show that the six compounds have good thermal stability below 190 oC， and have strong solid fluorescence emission properties. Among them， the compounds 4-6 can be used as fluorescent probes to detect Fe3+ and are not disturbed by other common metal ions. The detection limits of these probes are 8.70×10-6，1.64×10-6，1.01×10-6 mol/L， respectively. Moreover， the theoretical luminescence principle of compounds is analyzed by density functional theory（DFT） calculation.Keywords：8-Aminoquinoline;Oxadiazolidone;fluorescent probe;Fe3+ ion;density functional theory（DFT）- 217
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Published：2022-11-04
Luminescence Applications and Interdisciplinary Fields
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