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Latest Issue
Issue 3 ， 2022
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Upconversion Luminescence in Quantum Dots Enhanced Publication
Abstract：Photon upconversion(UC), a nonlinear optical process that converts multiple low-energy photons into a single high-energy photon, is of significant importance in many fields, such as laser, display, photovoltaic, information security, bioimaging and diagnosis. In compare with the well developed lanthanide-doped nanocrystals and triple-triple annihilation, UC quantum dots can achieve UC luminescence under a wide spectral excitation range, which are emerging as promising candidates for many photonic applications due to their wide spectral absorption, high luminous efficiency, near-infrared absorption, tunable energy band, small size and high stability. In this short review, we summarize the progress of upconversion semiconductor quantum dots with the description of basic mechanisms, recent progress of different types of UC quantum dots, especially UC dual quantum dots that based on excited state absorption, discuss the application potential of UC quantum dots in light-emitting diodes, detectors, solar cells and biomarkers, then we conclude with a brief prespective about the challenges and future prospects in this field.Keywords：upconversion luminescence;quantum dots;energy band engineering;Semiconductor nanocrystals- 1266
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Published：2022-04-07
Cover Story
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Research Progresses on Chemiluminescent Gold Nanoclusters Applied in Biological
in vitro Detection Enhanced PublicationAbstract：Gold nanoclusters are novel luminescent materials with simple preparation method, molecular size and quantum effect, which have been widely applied in chemiluminescence detection in recent years, especially in in vitro biological detection. This article reviews the progress of gold nanoclusters chemiluminescence(including electrochemiluminescence) system in the application of in vitro biological detection. First, the synthesis, structure, properties of gold nanoclusters and the basic principle of chemiluminescence system are introduced and explained theoretically. Next, recent reports are summarized on in vitro biological detection with gold nanoclusters, and strategies in literatures are overviewed and commented on how to improve the luminescent intensity and detection sensitivity. Finally, we give an outlook on the development trend of gold nanoclusters chemiluminescence system.Keywords：gold nanoclusters;chemiluminescence;electrochemiluminescence;in vitro biological detection- 363
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Research Progress on Pr3+ Doped Red Persistent Luminescent Materials Enhanced Publication
Abstract：Pr3+ doped afterglow materials have attracted much attention due to their stable and efficient red persistent luminescence. In recent years, the basic research and application exploration of Pr3+ doped red afterglow materials have made great progress. This paper summarizes the relationship between luminescence characteristics of Pr3+ ions and position of intervalence charge transfer band, overviews the recently reported luminescent material systems, discusses the optimization method to improve persistent luminescence performance, and introduces the burgeoning application directions of the related materials in information encryption, AC-LED, biological imaging, and stress-sensing. Finally, the existing problems in the research of Pr3+ doped red afterglow luminescent materials are pointed out, and the future research directions of Pr3+ doped red afterglow luminescent materials are prospected.Keywords：Pr3 + ions;afterglow materials;luminescence mechanism;adulteration- 390
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Published：2022-04-07
Invited Review
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Near-infrared Spectra and Laser Parameters of Yb3+ and Na+ Codoped CaF2-SrF2 Crystal Enhanced Publication
Abstract：15%Yb,20%Na∶CaF2-SrF2(Yb,Na∶CaF2-SrF2, CaF2∶SrF2=1∶1) single crystal with the ratio of 1∶1 for CaF2 and SrF2 is characterized by near-infrared spectra followed by the evaluation of laser parameters. The absorption bandwidth centered at 974 nm is 22 nm, together with absorption coefficient of 13.09 cm-1 and absorption cross section of 0.31×10-20 cm2. The fluorescence lifetime corresponding to energy transfer channel of2F5/2→2F7/2 is measured as 228 μs. The main emission band of Yb3+ ions in Yb,Na∶CaF2-SrF2 host is centered at 1 010 nm with a shoulder band peaked at 1 036 nm. The emission bandwidth under the excitation wavelength of 915 nm is fitted to be 56 nm by using the Lorentz method. The emission cross section reaches 6.52×10-20 cm2 at 1 010 nm and 4.11×10-20 cm2 at 1 036 nm under an excitation wavelength of 980 nm. On the other hand, the emission cross sections get 1.49 times and 1.68 times reduction at 1 010 nm and 1 036 nm under the excitation wavelength of 915 nm when compared with those under the excitation wavelength of 980 nm. Furthermore, the inversion population βmin of 0.34% and the saturation pump power of 290.58 kW·cm-2 are obtained under the excitation wavelength of 980 nm. It indicates that high dopant level of Yb3+ in Yb,Na∶CaF2-SrF2 single crystal could lead to the potential applications in near-infrared high energy laser system.Keywords：fluoride laser crystal;Yb3+ ions;absorption spectra;fluorescence spectra;saturation pump power density- 180
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GdF3∶Nd3+,Yb3+@NaGdF4 Nanomaterials for Near Infrared Fluorescence and Magnetic Resonance Dual-mode Imaging Enhanced Publication
Abstract：GdF3∶Nd3+,Yb3+ magnetic nanocomposites with near-infrared photoluminescence under 808 nm excitation were designed based on the energy transfer between Nd3+ and Yb3+. The influence of synthesis parameters on the morphology of GdF3∶Nd3+,Yb3+ was discussed. The obtained GdF3∶Nd3+,Yb3+ exhibits a wide emission band(970-1 070 nm) under 808 nm excitation. The co-doping system of Nd3+ and Yb3+ can realize the dual emission center of Yb3+ and Nd3+ as the emission center. It effectively improves the luminescence performance in the near-infrared region and overcomes the disadvantage of overheating biological tissues by fluorescence imaging under 980 nm excitation. An inert shell of NaGdF4 was grown on GdF3∶Nd3+,Yb3+ surface, which could improve the emission intensity dramatically. Meanwhile, the effect of NaGdF4 inter shell with different thicknesses on the luminescence enhancement of GdF3∶Nd3+,Yb3+ was studied. The final products GdF3∶Nd3+,Yb3+@NaGdF4 are paramagnetic with magnetization 0.45 A·m2/kg. This indicates that GdF3∶Nd3+,Yb3+@NaGdF4 has broad application prospects in both the fluorescence imaging field and magnetic resonance imaging(MRI) field.Keywords：near-infrared;energy transfer;magnetic resonance imaging- 204
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Bipolar Fluorenylcarbazole-based Host Materials for Efficient Red Phosphorescent Organic Light-emitting Diodes Enhanced Publication
Abstract：Achieving high-efficiency red phosphorescent organic light-emitting diodes(PhOLEDs) is still a challenge, which is largely related to the host material used in device fabrication. Two new bipolar hosts, 2-(9H-carbazol-9-yl)-7,7-dimethyl-5-(4-phenylquinazolin-2-yl)-5,7-dihydroindeno［2,1-b］carbazole(FC-CZ-PQZ) and 2-(4-(9H-carbazol-9-yl)phenyl)-7,7-dimethyl-5-(4-phenylquinazolin-2-yl)-5,7-dihydroindeno［2,1-b］carbazole(FC-BCz-PQZ), were designed and synthesised as host materials to fabricate red PhOLEDs. The two compounds exhibited excellent physical properties with high thermal stabilities and balanced charge transport. FC-BCz-PQZ has a better bipolar carrier transport compared to FC-CZ-PQZ. FC-BCz-PQZ-based device demonstrated good electroluminescence performance with the maximum current efficiency, power efficiency and external quantum efficiency of 13.5 cd/A, 14.2 lm/W and 14.8%, respectively, suggesting its promising application as a host material for red PhOLEDs.Keywords：Fluorenylcarbazole;Quinazoline;Red PhOLEDs;Bipolar hosts- 222
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Effect of Ta2O5 on Optical Properties of Tellurium Bismuthate Glass Enhanced Publication
Abstract：By using differential scanning calorimetry(DSC) method, this research indicates glass transition temperture(Tg) of a series of (90-x)TeO2-10Bi2O3-xTa2O5(x=0%, 2%, 4%, 6%, 8%)(TBT) glass is increased with more Ta2O5 added. The phenomenon of increasing Tg is mainly contributed to transformation of [TeO3] and [TeO3+1] to [TeO4] units. And the structure changes result in highly dense glass network structure which is supported by Raman spectroscopy and XPS charactreizations. Based on results of absorption spectrum and optical band gap equation calculation, when Ta2O5 increases from 0 to 8%, the optical band gap and Urbach energy of such glass samples show decresing trends. The third-order nonlinear optical properties of TBT glass demonstrate positive correlation with concentration of Ta2O5 through Z-scan measurement. The TBT glass with 8% Ta2O5 has 3.30×10-20 m2·V-2(2.36×10-12 esu) of third-order nonlinear susceptibility. Thus, the outstanding properties of TBT glasses pave a way of nonlinear optical applications.Keywords：tellurite glass;tantalum oxide;nonlinear optics- 152
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Published：2022-04-07
Synthesis and Properties of Materials
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Design and Performance of Quantum Dot Light-emitting Diode Based on TiO2 Modified Layer Enhanced Publication
Abstract：Due to high color saturation and high color purity, quantum dot(QD) light-emitting diodes(QLEDs) have become one of the hotspots in LEDs research for their potential application in lighting and display. Surface and interface issues have become a thorny issue which restricting the development of QLEDs with multilayer structure. In this paper, the interface between electron transport layer zinc oxide(ZnO) and QDs emitting layer was modified by inserting titanium dioxide(TiO2) layers with different thickness based on atomic layer deposition(ALD) technology. After inserting 0.270 nm TiO2 modified layer, the leakage current of the QLEDs was significantly reduced about an order of magnitude, and the average lifetime of the excitons increased from 15.94 ns to 16.61 ns, indicating that the insertion of the TiO2 modified layer can effectively prevent the exciton quenching in QDs emitting layer, thereby enhancing the current efficiency of the QLEDs under low driving voltage(about increased 15%). The above results are expected to provide a reference for the industrialization of QLEDs in the field of lighting and display.Keywords：quantum dot;light-emitting diodes;TiO2;interface modification- 136
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Failure Analysis of Multi-junction Cascade Vertical Cavity Surface Emitting Laser Enhanced Publication
Abstract：In this paper, the failure analysis of the self-developed 940 nm high-power triple junction vertical cavity surface emitting laser(VCSEL) single-emitter device after high temperature and high current aging failure is carried out. First, through the thermal resistance test, the junction temperature of the accelerated aging experiment was determined, and the aging acceleration factor was calculated to be 104. Subsequently, failure analysis was performed on the failed devices produced during the aging process. Through the L-I-V, forward and reverse V-I, optical and infrared appearance of the device before and after aging, near-field spot and transmission electron microscope(TEM), the performance and light-emitting mode changes of the device before and after aging were studied, and the failure location of the failed device was determined and the cause of the failure was analyzed. The device was confirmed by TEM image. The failure is caused by the growth of dislocations in P-DBR. This article is the first report on the failure analysis of multi-junction VCSEL devices in the world. It has certain guiding significance for continuing to optimize the internal structure design of VCSEL and improving process control capabilities, and to improve the life and reliability of multi-junction VCSEL devices.Keywords：vertical cavity surface emitting laser;multi-junction;failure analysis;reliability- 191
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Preparation and Performance of Luminescent Solar Concentrator Based on Surface Plasmon Resonance Effect Enhanced Publication
Abstract：The surface plasmon resonance effect of metal nanoparticles can enhance the absorption and scattering of incident light at a certain wavelength. Because of this unique optical property, the metal nanoparticles are developed for the applications of luminescent solar concentrators. In this paper, the Au nanoparticles with different concentrations are introduced to the luminescent solar concentrators based on the all-inorganic perovskite CsPbBr3 quantum dots and the thiol-ene polymer. The results show that the Au nanoparticles with suitable concentration can improve the external quantum efficiency of the luminescent solar concentrators by the surface plasmon resonance effect. When the doping concentration of Au nanoparticles is 2.0×10-6, the external quantum efficiency of the luminescent solar concentrator is 12.3%, which is enhanced by 78.2% compared with that of Au-free luminescent solar concentrator. With the further increase of Au nanoparticle doping concentration above 2.0×10-6, the external quantum efficiency of the luminescent solar concentrators decreases. According to the photoluminescence emission spectra and the time-resolved photoluminescence emission curves, excessive Au nanoparticle doping concentration leads to the non-radiative energy transfer process between the CsPbBr3 quantum dots and Au nanoparticles. The decreasing fluorescence quantum yield(ηPL,LSC) gives rises to decreasing external quantum efficiency of the luminescent solar concentrator.Keywords：perovskite quantum dot;Au nanoparticle;surface plasmon resonance effect;external quantum efficiency;non-radiative energy transfer- 161
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Published：2022-04-07
Device Fabrication and Physics
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Research Progress of Active Layer and Electrode Layer of Translucent Perovskite Solar Cells Enhanced Publication
Abstract：Translucent perovskite solar cells have the advantages of integrating lighting and power generation, and have huge applications in the fields of new energy vehicles and building integrated photovoltaic systems. Photovoltaic systems are mainly located on the top or roof or area of the car to achieve maximum light in the sun. The translucent solar cells are integrated into the car body or space at a height that can nutritionally increase the capacity and increase energy production. How-ever, how to ensure the photoelectric conversion efficiency of the translucent solar cells and have a good light transmittance has always been a defect in the light transmission of the scientific community. The design of new device structures, light-absorbing layers and transparent coatings have yet to be resolved. In terms of structure design, material selection and preparation technology, the latest research progress is summarized, and the development direction of the current research and the future development direction are discussed.Keywords：semi-transparent;perovskite;active layer;transparent electrodes- 243
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Synthesis and Conversion Efficiency Optimization of Quantum Dots Layer for Full-color Micro-LED Display Enhanced Publication
Abstract：In this paper, colloidal CdSe/ZnS quantum dots(QDs) with modified ligands are dispersed in photoresist and then patterned on blue InGaN/GaN Micro-LED by lithography process, demonstrating a high-resolution and highly efficient color conversion layer with critical dimension of 3 μm. The absorption/emission spectrum and photoluminescence quantum yield(PLQY) of the QDs color conversion layer(CCL) with different thickness and mixing ratio are systematically studied. To improve the conversion efficiency, TiO2 scattering particles are diffused into the QDs CCL to enhance the blue light absorption. Moreover, a tailored distributed Bragg reflector(DBR) is introduced to make the unabsorbed blue photons bounce back to the QDs CCL, which not only amplifies the blue light absorption but also strengthens the saturation of the converted colors. The PLQY of the QDs CCL is even increased after appropriate hard baking. Black matrix material is applied to suppress the light crosstalk among neighboring pixels, thus higher contrast and color saturation are obtained. The promising experimental results prove that the QDs photoresist is feasible to construct a high-resolution and highly efficient color conversion layer by lithography process, paving a novel and reliable pathway to monolithic full-color Micro-LED displays.Keywords：micro-LED;quantum dot;distributed Bragg reflector(DBR);color conversion;Scattering particles- 300
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Published：2022-04-07
Luminescence Industry and Technology Frontier
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Sensitive Detection of Captopril Based on “Off-On” Carbon Dots as Fluorescent Probe Enhanced Publication
Abstract：Fluorescent nitrogen-doped carbon dots(NCDs) were synthesized by a facile one-step microwave strategy using lemon juice and urea. The obtained NCDs show stable blue fluorescence with a high quantum yield of 53.1%. Hg2+ can efficiently coordinate onto the surface of NCDs by means of electrostatic interactions and remarkably quench the fluorescence of NCDs as a result of the formation of a non-fluorescent stable NCDs-Hg2+ complex(turn-off). Static fluorescence quenching towards Hg2+ is proved by the fluorescence lifetime measurements and the change of ultraviolet-visible absorption spectra. In addition, the fluorescence of NCDs-Hg2+ system was recovered with the addition of captopril(CAP) due to the ability of captopril to coordinate with Hg2+ and the formation of strong Hg2+—S bond. When captopril was added, Hg2+ combined with captopril rather than with NCDs resulting in the remove of Hg2+ from the surface of NCDs and a significant fluorescence restore of NCDs was observed(turn-on). Under the optimized conditions, good linearity for detecting captopril was attained over the concentration range 0.25-25 μmol·L-1 with a detection limit of 0.17 μmol·L-1. Moreover, this NCDs-based sensor was successfully applied for quantitation of captopril in tablets with satisfactory recovery.Keywords：Carbon dots;Fluorescence;Captopril;Hg(Ⅱ)- 229
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Fluorescent Detection for Cysteine/Homocysteine Using Hg2+ Modulated Nitrogen and Phosphorus Co-doped Carbon Nanodots Enhanced Publication
Abstract：A new kind of N,P-CDs with rich nitrogen content(10.0%) and high fluorescence quantum yield(23.64%) was successfully prepared using folic acid and N-(phosphonomethyl)iminodiacetic acid as precursors. Due to the charge transfer between Hg2+ and N,P-CDs, the fluorescence of N,P-CDs was quenched. Based on this, a cysteine/homocysteine(Cys/Hcy) enhanced nanoprobe was constructed using the stronger interaction between Hg2+ and -SH. Linear relationships were established within the range of 0.1-150 μmol/L for Cys and 0.1-100 μmol/L for Hcy, respectively. The limit detections of Cys and Hcy were 30 nmol/L and 50 nmol/L. In addition, the as-prepared N,P-CDs with strong anti-matrix interference ability could be used for real samples such as tap water and urine. N,P-CDs were applied to sensing Hg2+/Cys within living cells favorably based on their ultralow cytotoxicity and outstanding cell permeability, indicating the potential applications in bioimaging and biosensing.Keywords：N, P-CDs;fluorescent probes;cysteine detection;homocysteine detection;cell image- 137
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Synthesis and Performances of Triphenylamine Based Turn-on Fluorescent Probe for Fe3+ by An Enhancement Pattern Enhanced Publication
Abstract：Fe3+ plays an important role in many physiological processes, such as oxygen transport, DNA synthesis, myelin synthesis, mitochondrial respiration, neurotransmitter synthesis and metabolism. However, excessive Fe3+can induce cells to produce a large amount of ·OH and result in cell damage, which can also cause a variety of diseases, such as β-thalassemia, Parkinson‘s disease, epilepsy and Alzheimer‘s disease. Therefore, it is of great significance to detect and monitor Fe3+. In this paper, a fluorescence enhanced Fe3+ probe BL based on triphenylamine is designed and synthesized, and it is also applied to the recognition of Fe3+ in real water samples. The results show that the probe BL has a high sensitivity for Fe3+ recognition, and the detection limit is as low as 0.165 μmol·L-1. At the same time, upon the addition of Fe3+, an obvious change in the colour of the BL solution from turquoise to yellow is observed, allowing for colorimetric detection of Fe3+ by the "naked eye" . The 1∶1 coordination mode between BL and Fe3+ is further proved by high resolution mass spectrometry. Density functional theory(DFT) is used to calculate the changes of energy level and energy of the orbital before and after coordination with Fe3+ and explain the phenomenon of its fluorescence spectrum.Keywords：triphenylamine;iron ions;fluorescent enhanced probe;naked-eye;recognition- 175
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Published：2022-04-07
Luminescence Applications and Interdisciplinary Fields
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