最新刊期
卷 41 ， 期 10 ， 2020
- 摘要：In recent years, perovskite materials are considered to be the rising star of solar cells due to their good photoelectric performance and charge transport characteristics. Flexible perovskite solar cells(F-PSCs) that can be prepared by low-cost printing have the advantages of being light and flexible, and have broad application prospects in portable wearable electronics and photovoltaic buildings. By optimizing the perovskite light absorption layer, charge transport layer, substrate and electrode materials, the efficiency of F-PSCs has exceeded 20%. The rapid development of the preparation process has laid a solid foundation for the application of F-PSCs. This article focuses on the latest research progress of transparent conductive bottom electrode materials, electron transport materials, hole transport materials and counter electrode materials in F-PSCs. In addition, the influence of materials on the photoelectric performance and stability of F-PSCs and the optimization of ultra-thin perovskite light absorption layer were reviewed and summarized. Finally, we introduced the mass production and encapsulation technology of F-PSCs.关键词：flexible;perovskite solar cell;charge transport layer;electrode
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发布时间：2020-10-12 - 摘要：The development of Mn4+ activated red phosphor for white LEDs is one of the current research hotspots. Manganese, as a transition metal element, has partially filled d orbitals and can form various valence states other than Mn4+ in the prepared phosphors. The existence of other valence states, however, can affect the absorption and luminescence of the Mn4+ ions. In many related papers, the valence state of manganese ions of the as-prepared phosphors is not analyzed, or the adopted techniques are difficult to characterize various valence states of manganese ions qualitatively or quantitatively. This article reviews the valence-state characterization techniques of manganese ions, including the diffuse reflectance spectrum, the photoluminescence spectrum, the X-ray photoelectron spectroscopy, the electron paramagnetic resonance spectrum, the cathodoluminescence spectrum, the X-ray absorption fine structure spectrum, and the temperature-dependent magnetic susceptibility. The reliability of these techniques to qualitatively or quantitatively characterize the manganese valence is comparatively discussed. The influencing factors of the valence state of manganese ions and the regulating method of Mn4+ in phosphors are also summarized, with a view to benefiting the development of new efficient Mn 4+ activated red phosphors.关键词：white LED;phosphor;manganese ion;valence state analysis
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发布时间：2020-10-12 - 摘要：In recent years, narrow-band phosphors have attracted widespread attentions in the field of LED display due to the advantages of expanding display color gamut, improving color reproducibility and enhancing luminous efficiency. However, due to the limited number of narrow-band phosphors reported so far and the expansion effect of Eu2+ 4f-5d transition, the research and development of Eu2+-doped phosphors with narrow-bands for emerging fields still face huge challenges. This article overviews the currently reported Eu2+-activated UCr4C4 type phosphors with narrow-band emissions, describes the crystal structure characteristics, photoluminescence properties and their applications of Eu2+-doped UCr4C4-based nitrides, oxide and oxynitride phosphors, and discusses the structure-related luminescence properties. It is expected that the review could provide meaningful enlightenment for the design of novel rare earth doped emissions.关键词：UCr4C4;Eu2+ doped;narrowband luminescence
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发布时间：2020-10-12
Invited Review
- 摘要：Eu3+ doped germanate glasses were prepared by melting and quenching at high temperature. The luminescence properties of germanate glasses with different concentrations of Eu3+ under the excitation of 393 nm light were measured. The results show that the optimal concentration of Eu3+ is 4%. Eu3+ doped transparent germanate glass ceramics containing CaF2 nanocrystals were prepared by heat treatment on 4% Eu3+ doped germanate glasses. The XRD results of the glass ceramics show that the precipitated phase is pure cubic CaF2, without other impurity phases, and the grain size is about 13 ~ 19 nm. Under the excitation of 393 nm light, the luminescence intensity of glass ceramics increases with the increment of heat treatment temperature and time. At the same time, compared with germanate glass, the red emission of germanate glass ceramics is significantly enhanced under X-ray excitation. The results show that Eu3+ doped germanate glass ceramics containing CaF2 nanocrystals have potential application prospects in the field of X-ray detection.关键词：scintillating glass;Eu3+;germanate glass;glass ceramic
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发布时间：2020-10-12 - 摘要：Ba5-2xCexKx(PO4)3F and Ba3Ce1-xK(PO4)3F:xTb3+ phosphors were prepared by high temperature solid state method. Their structure, morphology, composition and photoluminescent properties were studied by XRD, SEM(including mapping and EDX), photoluminescence excitation and emission spectra. The results show that Ba3CeK(PO4)3F phosphor emits bright blue light under the excitation of UV light, while the emission of Ba3Ce1-xK(PO4)3F:xTb3+ phosphor gradually changes from blue light to blue green light and finally to green light as the Tb3+ doping concentration increases. The Ce3+ ions can strongly sensitize the luminescence of Tb3+ ions under UV excitation through the efficient energy transfer process from Ce3+ to Tb3+ ions. The emission intensity of Tb3+ in Ba3Ce1-xK(PO4)3F:xTb3+ reaches the maximum when the mole concentration of Tb3+ is x=0.20.关键词：phosphor;Ce3+ doped;Tb3+ doped;energy transfer;spectral control
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发布时间：2020-10-12 - 摘要：Using cucumber as raw material, fluorescent carbon nanodots were synthesized via hydrothermal method, by which the specific fluorescent detection of Fe3+ was achieved. The morphology and microstructure of carbon nanodots were characterized by transmission electron microscope and X-ray photoelectron spectroscope, and the fluorescent performance of carbon nanodots was measured by fluorescent spectroscope. The results indicated that the prepared carbon nanodots showed good dispersity, and the average size was about 3 nm. When the reaction temperature was 200 ℃ and the reaction time was 12 h, the prepared carbon nanodots have the optimum fluorescent performance. Moreover, the introduction of Fe3+ can quench the fluorescence of carbon nanodots, but other metal ions can not change the fluorescence intensity and emission wavelength of carbon nanodots, which indicates that the prepared carbon nanodots achieve specific fluorescence detection towards Fe3+.关键词：carbon nanodots;hydrothermal method;cucumber;green synthesis;Fe3+ fluorescent detection
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发布时间：2020-10-12 - 摘要：Carbon quantum dots(CQDs), a member of carbon nanomaterials family, have catching growing attentions in recent years due to their distinctive photoelectric properties, environmental-friendliness and cost-effectiveness. Moreover, it shows huge potential in photovoltaic and optoelectronic applications, such as solar cells, photoelectric catalysis, sensors and so on. In herein, the CQDs were synthesized by hydrothermal method with chitosan as precursor under acid, neutral and alkaline environment(pH=3, 7, 10). At the same time, the photoluminescence properties and structures of the obtained CQDs were characterized. The TEM characterization showed that with the increase of pH value from 3 to 10, the particle size decreased from 2.80 nm to 1.83 nm. These CQDs were also used as photosensitizer to assemble into sensitized solar cells(SSCs). Resultantly, the solar cells with the CQDs obtained under pH=3 exhibited the highest photoelectric conversion efficiency(PCE). In order to further improve the performance of SSCs, N719 dye was applied to prepare co-sensitized solar cells(co-SSCs) by combing with the CQDs. Owing to up-conversion characteristics and excellent carrier transport properties of CQDs, a PCE as high as 9.13% was achieved for CQDs/N719 based co-SSCs, which is significantly higher than that of CQDs- and N719-based SSCs individually. These research results open a new door for fabricating CQDs and assembling high efficient SSCs.关键词：nanomaterials;carbon quantum dots;sensitized solar cells;photoelectric conversion efficiency;pH value
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发布时间：2020-10-12 - 摘要：Preparation of p-type MgZnO film is still one subject of high-efficiency ultraviolet luminescence and solar-blind ultraviolet photodetectors devices. In this work, aiming at the problems of low carrier concentration and high resistivity in N-doped p type MgZnO film, using 99.99% pure nitrogen and argon as sputtering gas, p-type B-N co-doped MgZnO film and N doped MgZnO film were deposited on quartz substrate by radio frequency magnetron sputtering with B-N co-doped MgZnO target and N doped MgZnO target respectively. It is found that the prepared MgZnO films show p-type electrical properties by a Hall effect measurement. Compared with N-doped MgZnO film, the carrier concentration of B-N co-doped MgZnO film is increased from 5.53×1015 cm-3to 2.63×1017 cm-3, the Hall mobility is decreased from 0.83 cm2·V-1·s-1to 0.75 cm2·V-1·s-1, and the resistivity is decreased remarkably from 1.36×103 Ω·cm to 31.70 Ω·cm. The measurement of XRD and XPS reveals that B occupies Zn site or Mg site and N has three doping states. The first state is that N atom occupies O site which is the nearest neighbor with Zn or Mg atom, forming NO. The second state is that N2 occupies O site, forming (N2)O. The third state is that N atom occupies O site which is the nearest neighbor with B atom, forming B-N pair. Therefore, B doping can improve the N dopant acceptor concentration, affect little on holes scattering and reduce resistivity of p-type MgZnO.关键词：radio frequency magnetron sputtering;MgZnO thin films;B-N codoping;p-type
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发布时间：2020-10-12
Synthesis and Properties of Materials
- 摘要：Optical fiber fluorescence sensor combines the advantages of high sensitivity, strong discrimination of the fluorescence detection and small size, strong anti-interference ability of fiber. Because some of the fluorescent detection substances have a quenching effect on the fluorescence intensity, the optical fiber fluorescence sensor based on the quenching effect has important research significance. In this paper, the research progress of the optical fiber sensor based on the fluorescence quenching effect is reviewed. The detection mechanism of the fluorescence quenching effect is briefly described. The combination mechanism of the optical fiber and the fluorescence detection is classified and summarized according to the structure of the sensing optical fiber. On this basis, the applications of the optical fiber fluorescent sensor based on the fluorescence quenching effect in the fields of heavy metal ion detection, explosive detection and other fields are described. The interaction between the quencher and fluorescent material, and the performance index of the sensor are analyzed. Finally, the development direction of the optical fiber sensors based on fluorescence quenching effect is prospected.关键词：spectral detection;optical fiber sensing;luminescence mechanism;fluorescence quenching
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发布时间：2020-10-12 - 摘要：L-band SG-DBR lasers have wide application prospects in high-speed optical communication and passive optical networks. In this paper, using InGaAsP as the passive waveguide region material, the key parameters which are necessary to realize the wide-tuned SG-DBR laser in L-band are theoretically analyzed, including the reflection peak interval, number of sample period and duty ratio of the sampled grating. At the same time, the relationship between the sampling logarithm and the reflection characteristics of the front sampling grating(FSG) and rear sampling grating(RSG) is discussed by using the transmission matrix model. Finally, a set of optimized SG-DBR laser parameters were obtained, and the corresponding tuning range reached 47.6 nm.关键词：L-band;transmission matrix method;SG-DBR laser;wide tuning range
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发布时间：2020-10-12 - 摘要：In this paper, we designed an 850 nm liquid crystal tunable vertical-cavity surface-emitting laser(VCSEL) structure with internal coupling layer to optimize the wavelength tuning range and polarization stability of the device. The resonance wavelength and the corresponding threshold gain of the two polarization modes are analyzed under different liquid crystal layer thicknesses, and the effect of liquid crystal thickness on the tunable VCSEL polarization mode and wavelength tuning is studied. In addition, we add a coupling layer structure between the semiconductor cavity and the liquid crystal cavity, which can make the liquid crystal tunable VCSEL structure realize stable polarization mode and wider wavelength tuning range. The results show that the coupling layer structure can effectively increase the tuning range of liquid crystal tunable VCSEL to 41.1 nm. At the same time, because the polarization mode of o-beam is always suppressed, the liquid crystal tunable VCSEL can achieve stable single polarization mode output in the continuous wavelength tuning process.关键词：polarization stability;liquid crystal;vertical-cavity surface-emitting laser(VCSEL);wavelength tuning
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发布时间：2020-10-12
Device Fabrication and Physics
- 摘要：By means of the particle swarm optimization algorithm and density functional theory on two dimensional B6C6N6 structure prediction, we predicted that the lower-energy structure of BCN monolayer composed of C6, B3N3, and B2C2N2 ring, is vital to structural stability. The calculation of cohesive energy and phonon spectra indicate that the BCN is stable thermally and dynamically, respectively. Our HSE06 calculation shows that BCN is a direct-gap semiconductor with a band-gap of 2.60 eV. Furthermore, based on the deformation potential theory, the BCN monolayer has electron mobility (632.5 cm2·V-1·s-1along "zigzag" direction and 923.3 cm2·V-1·s-1 along "armchair" direction, respectively) and hole mobility (765.7 cm2·V-1·s-1 along "zigzag" direction and 622.6 cm2·V-1·s-1 along "armchair" direction, respectively), higher than that of MoS2. The higher carrier mobility indicates that BCN has good transport property. The calculation of optical properties shows that the peak of dielectric function of BCN is in good agreement with the peak of absorption spectrum and photoconductivity. The absorption peak in the visible light range is located at the photon energy of ~2.61 eV, which mainly originates the electron transition from the valence band maximum to the conduction band minimum. The results of this study provide a theoretical basis for the application of BCN in optoelectronic devices.关键词：Structure searching;Two dimensional BCN;Electric properties;first-principle
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发布时间：2020-10-12
Theoretical Calculation and Spectral Analysis
- 摘要：The LED light source module applied in the deep sea environment adopts encapsulated silica gel as the pressure compensation structure medium, which has the advantages of convenient assembly and simple structure compared with the traditional hydraulic compensation structure. According to the law of refraction(Snell's Law), the difference in the refractive index of different encapsulated silica gel will lead to different angles of total reflection of light in the sapphire lens window, thus affecting the light flux. Therefore, this paper explores the influence of different refractive index (1.41 to 1.55) and different thickness(1.6 mm to 3.0 mm) of encapsulated silica gel on the output light flux of the light source module. Tracepro simulation results show that the optical flux increases with the decrease of the refractive index of encapsulated silica gel. When the silica gel refractive index is fixed and the package thickness is 2.5 mm, the luminous flux of the light source reaches the maximum. At the same time, this paper designs the silica gel encapsulation experiment. The experimental results are consistent with the simulation results, further verifying the accuracy of the simulation results.关键词：deep sea lighting;LED;encapsulated silica gel;refractive index;thickness;Luminous flux
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发布时间：2020-10-12 - 摘要：Micro light-emitting diode(μLED) is one of the most cutting-edge display technologies in the world. It generally refers to the LED array with a single mesa size less than 50 microns. Compared with liquid crystal display(LCD) and organic light emitting diode(OLED) display, μLED display technology has its unique advantages: long lifetime, short response time, and high brightness. Most importantly, it enables the realization of highly integrated displays, which includes both high-PPI displays with much higher pixel densities than conventional display technologies, and highly integrated semiconductor information displays(HISID) that have been proposed first by us and contain certain non-display components. In many figures of merit of display technology, μLEDs perform excellently. However, as μLEDs greatly reduce the size of conventional LED devices and typically have an increased device density, many new technical and physical challenges have arisen, such as mass transfer technology, full-color display, etc. Therefore, μLEDs have not yet achieved any real industrialization. In this paper, the highly integrated μLED display technology research and progress are described systematically. First of all, the basic principle and structure of μLEDs are introduced, followed by the classification and review of the key technologies. Finally, the development trends and application prospects of the μLED display technology are analyzed.关键词：micro light-emitting diode(μLED);driver;mass transfer technology;colorization;high integration density
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发布时间：2020-10-12
Luminescence Industry and Technology Frontier
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