最新刊期
卷 44 ， 期 7 ， 2023
- 摘要：Spectral hole-burning holographic storage has the characteristics of high-density， anti-interference and low-energy-consumption， and has potential ability of storing massive “cold data”. Based on our own research experience， we briefly review the development process and existing bottlenecks of spectral hole-burning. We propose a new idea to achieve room-temperature holographic spectral hole-burning in a functional unit of transition-metal-oxide/noble-metal， which is based on the principle of plasmatic spectral hole-burning. Then we present the latest achievements in large-area holographic discs and compact-type holographic memory devices. We also have a prospect for future work on high-density holographic spectral hole-burning in frequency domain via orderly arrangement of functional units. A series of work of the author's group open up a new direction for high-density optical storage， and provide a useful idea for the development of transition-metal-oxide-based optoelectronic devices with high-integration.关键词：spectral hole-burning;transition-metal-oxide;plasmon;holographic storage
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发布时间：2023-08-02 - 摘要：At present， fluorescence imaging has become one of the important tools in biomedical applications， but it is very susceptible to the limited penetration of light and auto-fluorescence in tissues. Compared with the fluorescence imaging in visible region and the first near-infrared window（NIR-Ⅰ）， the second near-infrared（NIR-Ⅱ） fluorescence imaging show the deeper penetration depth， lower background noise， higher imaging resolution， sensitivity， and signal-to-noise ratio， thus demonstrating the promising applications in cerebrovascular imaging and diagnosis of major brain diseases. Based on this， we mainly focus on the construction of different NIR-Ⅱ fluorescent probes and several strategies to optimize their optical performance. Meanwhile， the recent progress of these probes in brain imaging is summarized and some issues facing the future clinical applications are discussed.关键词：fluorescence imaging;NIR-Ⅱ;fluorescence probe;Brain diseases
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发布时间：2023-08-02 - 摘要：In recent years， upconversion emission of rare earth nanocrystals， which can convert near-infrared light to short-wavelength visible or near-infrared one， has attracted extensive attention from researchers in the fields of biological imaging， nanothermometer， solar cells， and so on. For multi-field applications， upconversion emission of rare earth nanocrystals needs to improve the luminescent intensity， luminescent wavelength selectivity， and excitation wavelength. In this paper， we briefly review the research progress in improving the color， luminescence intensity， and luminescence lifetime of upconversion emission on the basis of understanding the energy transfer pathway and upconversion emission process through the design of composition， structure and core-shell structure at the nanoscale. In addition， the coupling between nanocrystals and precious metal surface electromagnetic fields， surface organic molecules and ambient temperature is also concerned. The research trend of increasing the intensity of rare earth upconversion luminescence in terms of increasing radiation transition probability and reducing non-radiation quenching is also mentioned.关键词：rare earth nanocrystals;upconversion emission;core/shell structure
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发布时间：2023-08-02 - 摘要：Solar-blind ultraviolet photodetectors have broad application prospects in the fields of national defense and civilian use. The solar-blind ultraviolet photodetectors based on wide bandgap semiconductor materials are recognized as new generation of ultraviolet detector with the characteristics of no expensive filter， low working voltage， all-solid-state， small size， light weight， strong anti-interference ability， and wide operating temperature range. Among these wide bandgap semiconductors， gallium containing oxides with Ga2O3 as a typical representative have become research hotspot in the field of microelectronics and optoelectronics because of their excellent electrical and optoelectronic properties， especially their unique characteristics such as intrinsic solar-blind， high temperature resistance， high pressure resistance and good chemical stability， which makes such materials show great potential in the field of solar-blind ultraviolet photodetectors. In view of this， this article reviews the research progress in the past five years of gallium-based oxide films such as Ga2O3 with different crystal structures， gallate oxide， gallium aluminum （or tin， indium） oxide and their solar blind ultraviolet detectors.关键词：Solar-blind;Ultraviolet Photodetectors;gallium oxide;Gallium-based Oxide;Gallate oxide;Gallium Containing Ternary Oxides
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发布时间：2023-08-02 - 摘要：As a new generation of solid-state lighting source， white LED has shown outstanding performance advantages in energy conversion efficiency， brightness， chemical stability and environmental protection， and is widely used in the lighting field. Among its various white light construction methods， “near ultraviolet LED+ multicolor phosphors” is more conducive to the realization of high color rendering index and low color temperature healthy lighting， which has been highly concerned. The development and performance control of high-quality multi-color luminous materials is also a research hotspot in recent years. This paper introduces the latest development of Eu2+/Ce3+ activated luminescent materials for near ultraviolet LED， including the performance optimization of commercial powder and the development of new system， and discusses the means of material design and performance control. Finally， some opportunities and challenges of luminescent materials for near ultraviolet LED are discussed， This review provides reference and guidance for the development of white LED.关键词：rare earths;luminescent materials;n-UV LEDs;property regulation
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发布时间：2023-08-02 - 摘要：Lanthanide ion （Ln3+）-doped disordered materials exhibit excellent downshifting and upconversion luminescent properties， which can be widely used in a variety of optical and optoelectronic fields through luminescence modulation. The optical properties of Ln3+ ions are closely related to the local structure of crystal field. Thus， by using Ln3+ as a sensitive structural probe， the local structure and local site symmetry of Ln3+ dopants in luminescent materials can be determined. Meanwhile， it is also an effective strategy to optimize the luminescence of Ln3+ by modulating the local site symmetry of the Ln3+-doped disordered materials. In this review， we first clarify the crystallographic lattice site symmetry and spectroscopic lattice site symmetry of Ln3+-doped disordered crystals. Then， we systematically summarize the latest achievements of downshifting/upconversion luminescence manipulation by changing the microstructures around Ln3+ dopants， including internal composition and external field regulation. Finally， the challenges and prospects of Ln3+-doped disordered luminescent materials are discussed in detail.关键词：Disordered crystals;luminescent materials;Local site symmetry;Lanthanide doping;Luminescence manipulation
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发布时间：2023-08-02 - 摘要：Transition metal （TM） activators have been widely studied for their extraordinary optoelectronic properties and great potential application in near-infrared luminescence or persistent luminescence， infrared laser， phosphor-converted white light-emitting diodes， luminescence thermometry and so on. However， due to the multiple valence states and multiple site occupancies， and the strongly local-environment-dependent optical properties， it is challenging to determine the sites and valences of the luminescent center， to decipher the luminescent mechanisms and to predict the photoluminescence properties of TM activators in solids. Here， first-principles calculations have been performed to study the thermodynamic and optical properties of TM ions in solids. The defect formation energies are calculated to analyze the effects of intrinsic defects and the site occupancies， valence states， distribution and concentration of TM ions in host. The local environment dependent luminescence is analyzed by calculating the excited-state energy levels of TM activators in various lattice environment. The configuration coordinate diagrams are constructed to analyze the excitation， relaxation and emission processes. Then， a theoretical scheme is proposed to regulate the site-occupancy， valence states and optical transitions of TM ions in solids via tuning the sintering atmosphere， coexistence conditions， and especially co-doping impurities. We select several typical systems to show the rationality and effectiveness of first-principles calculations， which include the mechanisms of residual infrared absorption in Ti∶Al2O3 crystal and the method of mitigating or eliminating the infrared absorption， the site occupancies and optical transitions of Mn2+，Mn3+，Mn4+ in typical spinel and garnet hosts， the site occupancies， valence states and optical transitions of Cr3+/4+ ions in oxide compounds. The results show that first-principles calculations form effective approaches for elucidating the multi-site and multi-valence nature of TM ions in solids and predicting their optical transitions， which are beneficial for the rational design and optimization of related optical materials.关键词：transition metal ions;optical transitions;first-principles calculation
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发布时间：2023-08-02 - 摘要：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°， 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 TADF. These results are valuable for understanding the role of solvation in conformational relaxation and TADF emission， and provide guidance for the design and synthesis of TADF molecules.关键词：organic donor-acceptor systems;thermal activated delayed fluorescence;solvation;intramolecular charge transfer
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发布时间：2023-08-02 - 摘要：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.关键词：self-assembled semiconductor quantum dots;excitons;spins;optical microcavities;optical waveguides
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发布时间：2023-08-02 -
Research Progress on Photocarrier Dynamics in Two-dimensional Materials and Their Heterostructures 增强出版
摘要：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 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.关键词：two-dimensional material;transient absorption;carrier dynamics;ultrafast laser- 1219
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发布时间：2023-08-02 - 摘要：Currently， organic and perovskite materials have been widely used in fields such as luminescent displays and solar cells. To better understand the characteristics of these materials and optimize their performance， researchers need to have a thorough understanding of their excited state dynamics. Therefore， the use of magneto-opto-electronic comprehensive methods has become an important way to study these materials. Through these methods， the excited state dynamics of organic and perovskite materials can be accurately characterized， and detailed structural features such as electron-hole separation processes and intramolecular polarization can be obtained. In addition， these methods can also study the magneto-optical properties and electrical properties of materials， thereby providing support for interdisciplinary research on these materials. This article combines the author's research work to elaborate on the relevant research on nonlinear luminescent films and photovoltaic devices based on perovskite and organic materials using magneto-opto-electronic research methods. We can better understand the performance and characteristics of these materials and lay the foundation for the development of more advanced optoelectronic devices based on these studies.关键词：organic;perovskites;magneto-opto-electronic;interdisciplinary
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发布时间：2023-08-02 - 摘要：The blue OLED material plays a vital role in the field of electroluminescence. Based on high-energy excited state transition， the “hot exciton” materials show the potential of excellent blue light emitting. We designed and synthesized a novel D-π-A structure molecule TACN using anthracene as the core building unit， triphenylbenzene as the weak donor and phenylcyanogen as the acceptor by adjusting the ability of pushing and pulling electrons. Distorted triphenylbenzene provides a highly distorted molecular conformation， which effectively attenuates the quenching effect in the aggregated state. Therefore， TACN exhibits a high fluorescence quantum yield （47% in the aggregated state）. The experimental results and theoretical analysis show that TACN has the “hot exciton” characteristic， and its large T2-T1 gap （1.45 eV） effectively hinders the internal conversion （IC） process from T2 to T1， while its small T2-S1 energy difference （0.18 eV， T2> S1） facilitates the reverse intersystem crossing （RISC） process. Non-doped devices based on TACN exhibit dark blue emission （λmax= 444 nm）， full width at half maximum （FWHM） of 59 nm， and color coordinates of （0.17， 0.13）. Its maximum external quantum efficiency （EQEmax） is 8.3% and corresponding exciton utilization （EUE） is up to 88.7%.关键词：organic light emitting diodes;hot exciton;blue emitter;anthracene;reverse intersystem crossing
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发布时间：2023-08-02 - 摘要：Aiming at the current requirement for processing of pure copper， pure gold and other metal materials， a fiber coupled blue diode laser source with continuous output power up to 500 W was fabricated. According to the ray paths simulation of diode laser by ZEMAX， the experiment of high-power blue diode laser source for material processing was carried out. In the experiment， a TO packaged blue laser diode single emitter was adopted as the emitting unit. Due to the TO packaged structure with flat output window mirror， it was designed for fast and slow axis collimator with longer back working distance to obtain collimating beam with low divergence angle and high beam quality. The beam of 144 single-tube blue diode laser devices were combined by space and polarization combination to couple into a 200 μm/NA 0.2 fiber. Under the cooling with industrial water， the output power of 523 W and the wall-plug efficiency of 29% for blue diode laser source were demonstrated from the 200 μm/NA 0.2 fiber at the 3 A drive current. The laser light source had the potential application in non-ferrous metal processing.关键词：blue diode laser;fiber-coupled;laser beam combination;laser processing source
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发布时间：2023-08-02 - 摘要：Low hole injection efficiency is a key factor limiting the performance of blue quantum dot light-emitting diodes （QLEDs）. Improving the conductivity of PEDOT∶PSS to increase the hole injection efficiency of devices is of great importance for improving the performance of blue QLEDs.Because of the high conductivity， abundant surface functional groups， and good hydrophilicity of the two-dimensional material titanium carbide （Ti3C2Tx）， the conductivity of PEDOT∶PSS could be improved by using exfoliated Ti3C2Tx dopant. Here， the HCl/LiF etching method was employed to prepare single-layer Ti3C2Tx nanosheets and dope into PEDOT∶PSS for the fabrication of blue QLEDs devices. As a result， the blue QLEDs device using PEDOT∶PSS-0.1%Ti3C2Tx thin film as the hole injection layer presented the EQE and current efficiency of 15.2% and 14.42 cd·A-1， respectively. Compared to the value of a reference device of 9.09% and 7.68 cd·A-1， an great improvement of 67% and 87% were achieved， respectively. Ti3C2Tx nanosheets play a dual role in enhancing the performance of blue QLEDs. The Ti3C2Tx nanosheets induce a conformational change of PEDOT from a benzoid state to a quinoid state， forming densely packed large-sized PEDOT nanocrystals and connecting these conductive nanocrystals to construct new charge transfer pathways， which increase the conductivity of the composite layer. In addition， Ti3C2Tx doping realizes the work function regulation of PEDOT∶PSS， improving the hole injection efficiency of blue QLED devices.关键词：Ti3C2Tx nanosheets;blue light-emitting diode;hole injection;energy level regulation
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发布时间：2023-08-02 - 摘要：Mechanoluminescent （ML） materials show unique energy conversion features from mechanical stimulation to photon emission， making them widely used in mechanical sensing fields such as structural health diagnosis， information anti-counterfeiting， bioengineering， and electronic skins. However， the species of reported ML materials are rare and the understanding on the ML-related charge carrier transportation is insufficient， which significantly limits its development and application. In this work， novel mixed-anion typed ML materials namely Ba2Gd（BO3）2Cl∶Ln （Ln=Eu， Tb， Dy， Sm， Nd） were developed， and the charge carrier transportation processes involved in photoluminescence （PL） and ML were examined. The crystal structure， morphology， PL/ML properties and mechanism of the samples were studied by X-ray diffraction， scanning electronic microscopy， and steady-state and transient spectral techniques under multi-mode excitation. The experimental results indicated that the emissions of Ba2Gd（BO3）2Cl∶Eu were peaked at 536， 594， 613， 625， 654， 695，710 nm under 280 nm excitation. The first broad emission and other sharp ones were assigned to Eu2+ and Eu3+， respectively， showing a mixed valence states of doped Eu ions. Interestingly， the Ba2Gd（BO3）2Cl∶Eu almost exhibited orange emission from Eu3+ under mechanical stimulation， which may be attributed to the preferential excitation of valence band electrons in the host under stress. This study also showed that the optimal doping Eu concentrations in Ba2Gd（BO3）2Cl for PL and ML were both at 2%， and the mechanoluminescent intensity was linearly related to the impact energy in the range of 0.23-1.55 mJ. By changing the type of doped lanthanide， we expanded the wavelengths of ML from visible to near infrared region. This work may provide a new way to understand the mechanism of ML in phosphors including mixed valence states and the materials presented in this work show promoting applications in the field of advanced stress sensing.关键词：mechanoluminescence;rare earth doped luminescent materials;mixed-anion compound;energy transfer;mechanoluminescent mechanism
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发布时间：2023-08-02
Invited Paper
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