摘要:The vertical-cavity surface emitting laser(VCSEL) was invented 40 years ago, where a lot of unique features can be expected, such as small footprint, low power consumption, high efficiency, long lifetime, circular beam and two-dimensional arrangement and so on. In recent years, the market of VCSELs has been growing up rapidly, and VCSELs are now key devices in the fields of 5G communication, optical information storage, 3D sensing, material processing, light detection and ranging(LiDAR), and laser display. For different application requirements, VCSEL has great achievements in the area of power, efficiency, speed and wavelength. In this paper, firstly, the research history and advantages of VCSEL are introduced; then, the research progress and application status of VCSEL at high power, high speed and high temperature are reviewed; lastly, the latest application of VCSEL is introduced, and the market of VCSEL is prospected.
关键词:vertical-cavity surface emitting laser(VCSEL);high power;high speed;high temperature
摘要:Compared to the visible range(Vis, 400-700 nm) and first near-infrared window(NIR-Ⅰ, 700-1 000 nm), fluorescence-based imaging in the second near-infrared window(NIR-Ⅱ, 1 000-1 700 nm) possesses the merits of high sensitivity, spatiotemporal resolution and signal to noise ratio(SNR) with increasing tissue penetration depths benefiting from the optical scattering and auto-fluorescence in the biological tissue, leading to widespread application in the fields of tumor diagnosis, biosensing, in vivo molecular detection and immunoassay. Among of several NIR-Ⅱ fluorescence probes, lanthanide-doped luminescence nanomaterials have attracted more attention in development of NIR-Ⅱ fluorescence imaging, owing to the advantages of high photostability and chemostability, narrow emission band widths, tunable emission wavelength and lifetime. Therefore this work takes the mechanisms and constitutions of lanthanide-doped luminescence nanomaterials as starting points and systematically summarizes the recent progress in the biomedical imaging and biosensing applications of lanthanide-doped luminescence nanomaterials. The problem to be resolved and its future development are discussed.
摘要:Lead halide perovskite micro/nanostructures have been regarded as prospective optoelectronic materials in light-emitting diodes(LEDs), lasers and other optoelectronic devices due to their large absorption coefficient, high photoluminescence quantum yield, tunable bandgap, and narrow emission bandwidth. Herein, we review the advances on light amplified stimulated emission of lead halide perovskite micro/nanostructures and thin films. The influences of crystal dimensions and pumping modes on lasing performances, including the threshold and lasing modes are discussed. The lasing emissions based on perovskite materials are also introduced, and the outlook toward challenges and future prospects of the applications are discussed.
摘要:Polymers with long-lived persistent luminescence have exhibited the characteristics of amorphous structure, excellent process properties, long luminescence lifetime and low cost, which were important to develop the potential application for the pure organic long-lived persistent luminescent materials. In order to obtain the polymers with long-lived persistent luminescence, the current method was to utilize the spin-orbit coupling of heteroatom or heavy atom to improve the inter-system crossing channels of singlet and triplet excitons; and polymer matrix with intramolecular and intermolecular interactions of hydrogen bond, halogen bonding, ionic band and so on will provide the rigid environment for phosphorescent groups to restrain the non-radiative transition and quenching of triplet excitons. Based on these, this article reviewed the research progress of polymers with long-lived persistent luminescence in recent years, as well as put forward the opportunities and challenges in the future development process.
关键词:polymer materials;persistent luminescence;amorphous state;room temperature phosphorescence
摘要:Laser diode(LD) is regarded as the next-generation solid-state lighting. Color converters are the key luminescent materials in determining white light quality in LD lighting. The yellow-emitting Y3Al5O12:Ce3+(YAG:Ce3+) is extensively researched in LD lighting. To migitate the thermal effect induced by the high-power density of blue LDs, remote encapsulations of phosphor in glasses/film, single-crystal phosphors, (transparent) ceramic phosphors are proposed. This paper reviews and summaries recent progress of YAG:Ce3+ for LD lighting application and looks forward to its future development.
关键词:YAG:Ce3+;ceramic phosphors;phosphor in glass;phosphor film;white laser diode lighting
摘要:Towards the strong market demand for high power lightings, the all-inorganic fluorescent glass ceramics with excellent optical property and thermal/chemical stability are booming. In this work, a silicon-based nitride glass ceramic fluorescent conversion material embedded with La3Si6N11:Ce3+(LSN:Ce) phosphor was prepared based on a low temperature co-sintering method. It was demonstrated that LSN:Ce phosphor was less corroded by glass components during co-sintering, with its structure showing no obvious change, and so, good luminescent properties were retained with quantum efficiency of 79% and fluorescence integral intensity decreased only by ~14% at 150 ℃. The fabricated high-power white LED lighting source yields luminous efficacy of 54.8 lm/W, CCT of 5 712 K, CRI of 70.1, and chromaticity coordinate of (0.328 0, 0.369 0), upon 350 mA current driven. The constructed laser lighting source yields luminous flux of 118.48 lm, CCT of 7427 K, CRI of 56.2, and chromaticity coordinate of (0.298 2, 0.322 6), under 0.8 W excitation power. It was speculated that the thermal and light saturation phenomena occur in LSN:Ce fluorescent glass ceramics upon high-power blue laser excitation. After further optimization of material composition, preparation process, and device structure, LSN:Ce fluorescent glass ceramics are expected to be applicable to high-power lighting fields, such as automobile headlights and searchlights, and so on.
摘要:Gadolinium aluminum garnet(Gd3Al5O12, GdAG) is an excellent luminescent host material. But GdAG is easy to decompose during high temperature calcination, which makes it difficult to obtain a pure phase GdAG-based luminescent material. In recent years, research has confirmed that substituting the smaller radius Ln3+(Ln=Y, Lu, Tb) for part of Gd3+, or replacing the Al3+ with the larger radius M3+ to expand the dodecahedral gap, can stabilize the GdAG lattice and thus obtain a pure phase GdAG-based luminescent material. This article reviews the research progress of GdAG-based luminescent materials including the lattice stabilization, down-conversion luminescence, and up-conversion luminescence, and also discusses the preparation and performances of GdAG-based single crystals, thin films and ceramics, and their applications in radiological detection and medical imaging.
摘要:Rare earth or transition metal ions doped into fluorescent materials have a wide range of applications, such as multiple anti-counterfeiting, optical information storage, temperature sensing and other fields because of its environmental protection, easy preparation, high efficiency, low cost, long luminous life, full spectrum, high brightness, especially in the LED lighting field. However, the poor thermal stability of fluorescent materials is still a significantly challenge, which limits its rapidly applied development, particularly in the high temperature environments. Recently, under the excited of thermal disturbance, the capture and release processes of carriers from defect structure have been widely studied as an effective way to suppress the thermal quenching effect of fluorescent materials. This paper mainly focused on the summaries on the effect of the defect structures on the thermal stabilities of the fluorescent material. Besides, the influence of the defects structures, acting as the trapping centers, on the capturing and releasing processes of carriers, and the suppressing process of thermal quenching phenomenon are also summarized. Finally, the above critical issues in the current research are summarized and prospected.
关键词:Fluorescent materials for LED applications;Defect structure;thermal stability
摘要:In recent years, the afterglow phenomenon of carbon dots(CDs) has aroused broad research interest. Compared with the traditional organic compounds or inorganic coordination compounds with afterglow, the CDs not only retain the classical characteristics of carbon materials such as good biocompatibility and low toxicity, but also own the advantages such as adjustable, luminous color, easy preparation, photostable properties and containing no heavy metals. Therefore, the CDs with afterglow have important application prospects in the areas of information encryption, biological imaging and ion detection,etc. This paper summarizes the synthesis methods of afterglow CDs in recent years from two aspects of restricted system and intrinsic emission system, and then briefly introduces the mechanism of afterglow emission of CDs, after that addresses the application of afterglow CDs in the fields of anti-counterfeiting, information encryption, sensing and biological imaging in detail. Finally, some ideas on how to optimize the synthetic strategy of CDs and further develop more practical usages of afterglow CDs are proposed.
摘要:Due to the advantages of excellent imaging contrast and high spatial resolution, red emissive carbon dots(R-CDs) have attracted intensive attention. However, most of the reported R-CDs exhibited low photoluminescence quantum yield(PL QY), wide half peak-width(FWMH), and excitation-dependence property(excited mainly by blue or green light), which limits practical applications. Therefore, it is of great importance to furtherly elucidate the PL mechanism of R-CDs and achieve excitation-independent PL property as well as high PL QY. In this paper, the PL influencing factors of red emission including the quantum confinement effect, surface states and aggregation behaviors have been explained. Then, the regulatory mechanism of different reaction conditions such as the precursor and reaction reagent is investigated in details. Besides, we have briefly introduced the current applications of R-CDs in the fields of light emitting diodes and bio-imaging. Finally, attempts to realize the state-of-the-art performance of R-CDs is prospected.
摘要:Non-fullerene acceptor materials are one of the most popular organic optoelectronic materials at present stage. Organic bulk heterojunction(BHJ) solar cells based on non-fullerene acceptors(NFAs) have been developing rapidly, and their single-junction power conversion efficiencies (PCE) have reached 18%. The mutual conversion between singlets and triplets in organic semiconductors under the magnetic field will affect the dissociation and recombination for electrons and holes, thereby will have a certain impact on the photovoltaic performance. Moreover, the triplet excitons have a longer lifetime and diffusion distance, as well as higher probabilities for the triplet-charge reaction, which gives rise to the photocurrent, so that the triplet material has a certain effect on the improvement of photovoltaic performance. Thus, this article mainly discusses non-fullerene organic solar cells from the following aspects. Firstly, to discuss the effect of charge separation, recombination and energy loss on the open-circuit voltage; secondly, to talk about the spin-dependent photophysical process for the organic solar cells under the magnetic field and the application of the triplet materials in organic solar cells, both of which influence the improvement of photovoltaic performance; finally, a prospective for further improvements of the organic photovoltaic performance and the spin problem under the organic semiconductor magnetic field will be given.
关键词:non-fullerene organic solar cells;charge separation and recombination;energy losses;magnetic field effects;triplet acceptor materials
摘要:In virtue of the separation of excitation and emission, background-free autofluorescence, large area imaging and convenient operation, persistent luminescence nanoparticles(PLNPs) have attracted widespread attention in the field of optical diagnosis. However, with the increasing demand for integrated diagnosis and treatment, the single function of the existing PLNPs limits their technological breakthroughs in the miniaturized and integrated diagnosis and treatment units. Herein, in this review, PLNPs which can meet the integration requirements of biomedical diagnosis and treatment are discussed. Then the design strategies of developing these nanotheranostics are elaborated. Finally, the research opportunities for PLNPs nanotheranostics are prospected.
摘要:Sulfur nanodots(S-dots) is a kind of new luminescent nanomaterials, which has the advantages of non-toxic, abundant on raw materials, easy to process. Compared with traditional semiconductor quantum dots, perovskite quantum dots and carbon dots, the synthesis, optical properties and applications of S-dots are still in the primary stage. Summarizing the research progress of S-dots will greatly promote the relative works about both fundamental research and applications. In this review, the synthesis, characterizations, optical properties and applications in the fields of analytical sensing, bioimaging and optoelectronic devices of S-dots are summarized. We end up this review with the scope of research directions and prospects of S-dots. We hope this review can provide some clues for the researchers in this field.