最新刊期
卷 41 ， 期 9 ， 2020
- 摘要：Phosphors activated with Mn4+ ion are gaining prominence in the field of solid-state lighting as generators of red photon. In the present review, we focus on several important points that are fundamentally important to produce a commercially useful phosphor. This includes an understanding of the Mn4+ energy levels in the free state and in the crystal fields and of the host dependent variations in the Mn4+ emission wavelength. Additionally, we formulate several practical recommendations on how to tune the emission wavelength and emission intensity of Mn4+-doped phosphors. The main spectroscopic parameters of the Mn4+ ion in more than 100 phosphor materials are collected and discussed.关键词：Mn4+ ions;red phosphors;white LED2173|779|6更新时间：2020-09-10
- 摘要：Up-conversion luminescence material has been widely studied as the imaging agent due to its unique characteristics of anti-Stokes emission, deep excitation light imaging, low background self-fluorescence, and stable physical/chemical property, thus its application has been developed gradually. However, the low efficiency restricts the application in the biomedical field of up-conversion luminescent materials. Metal nanoparticles have unique local surface plasmon resonance and can effectively enhance fluorescence intensity. In this paper, discrete dipole approximation simulation of metal modulation to rare earth from theoretical guidance and experimental verification to biological use were reviewed. The electromagnetic characteristics of the composite can be obtained by the simulation, and plasma resonance peak(position and intensity) can be predicted, in order to guide the design and synthesis with the final luminescence test validation. In this review, six typical different rare earth-metal composites were designed and synthesized with enhanced fluorescence effect, and the application in biological imaging and therapy field was implemented.关键词：up-conversion luminescence;surface plasmon resonance;near infrared laser403|382|0更新时间：2020-09-10
- 摘要：Time-resolved imaging is an emerging type of imaging technique which can resolve long lifetime luminescence signal against short lifetime background signal in the time domain. The suppression of autofluorescence and scattering background endows this imaging technique with high signal-to-noise ratios and sensitivities. Lanthanide-doped nanomaterials have unique optical properties that make them suitable to serve as τ-dots for time-resolved imaging, such as being able to emit a multitude of narrow-band emissions in biological windows, being photostable under high laser irradiance, and having ultralong luminescence lifetimes in the μs-ms range about more than three orders of magnitude longer than the ones of biological endogenous fluorophores. Importantly, manipulation of the nanostructure and composition of lanthanide doped nanomaterials can result in a precise control over the luminescence lifetime, thus producing a set of lifetime-encoded biolabels for high-throughput multichannel detections. This review presents the general strategies utilized to regulate the luminescence lifetime of lanthanide-doped nanomaterials, highlights the most recent advances of utilizing them for time resolved imaging, and casts a look at their future developments.关键词：lanthanide-doped nanomaterials;lifetime;time-gated imaging;lifetime-encoded imaging643|645|0更新时间：2020-09-10
- 摘要：The development of green, environmental, sustainable chemical processes is currently a huge challenge for environment, energy and chemistry. Solar-driven photocatalytic chemical fuels preparation, degradation of pollutants and transformation of high value-added products is an effective pathway to solve the current energy and environmental problems. In recent years, metal halide perovskites as an emerging and high-efficiency photocatalyst have gained widely interest. In this paper, we systematically reviewed the research advances of metal halide perovskites in photocatalytic hydrogen evolution, photocatalytic CO2 reduction and photocatalytic organic transformation. The photocatalytic mechanism of metal halide perovskites and the key challenges in photocatalysis applications are described, and the further development of metal halide perovskites photocatalysis is analyzed and prospected.关键词：metal halide perovskites;photocarriers;photocatalytic hydrogen evolution;photocatalytic CO2 reduction;photocatalytic organic transformation671|1233|3更新时间：2020-09-10
Invited Review
- 摘要：Aggregation-induced emission(AIE) has become a hot research topic in materials and chemistry sciences. Compared with the prosperous research on low-mass luminogens with AIE characteristics(AIEgens), the AIE polymers, featuring the advantages of excellent film-forming ability, synergistic effect and multifunctionalizaiton, etc., are less developed. In this paper, the advantages of AIE polymers over low-mass AIEgens will be discussed based on their properties and applications, and the perspective on their future development direction will also be briefly presented.关键词：aggregation-induced emission;polymer;synergistic effect;high-tech applications629|648|5更新时间：2020-09-10
- 摘要：Long persistent luminescent(LPL) materials have shown great promise in various fields due to their unique optical properties. Based on our own and literature research, we herein organize the basic understanding and cutting-edge findings in inorganic, organic, metal-organic LPL materials, including the frontiers of LPL mechanism, disputes, pros and cons of different fields, and facing the future demands and prospects. Like the shining pearl in the night sky, the light of science and truth is always the power to encourage scientists to strive hard and work along.关键词：luminescent materials;long persistent luminescence;inorganic;organic;metal-organic821|2225|4更新时间：2020-09-10
40th Anniversary Special Column——Young Scientist on The Road
- 摘要：A new cross-linkable electron transport layer(ETL) material, 2, 4, 6-tris(4'-vinyl-[1, 1'-biphenyl]-3-yl)-1, 3, 5-triazine(TV-T2T) was designed and synthesized. The film formation of the cross-linkable material TV-T2T has the excellent solvent resistance. The lowest unoccupied molecular orbital(LUMO) level of TV-T2T is -3.5 eV, which could deliver efficient charge injection from the zinc oxide(ZnO) to the emission layer. In addition, the surface roughness of 2.27 nm in the film of triple-layer ZnO/TV-T2T/2, 6-Dczppy:Ir(mppy)3, is lower than that of the film without TV-T2T(2.39 nm), resulting in a reduced leakage current. The solution-processed inverted OLED with ETL material TV-T2T, achieved an EQE of 5.1% compared to the 3.0% EQE of the device without TV-T2T layer, demonstrating an improvement of 1.7-fold for the inverted OLEDs.关键词：cross-linkable material;electron transport layer;electron injection property;solution processing;inverted organic light emitting diodes224|323|0更新时间：2020-09-10
- 摘要：In this research, the Yb3+/Ln3+ (Ln=Ho3+ and Tm3+) doped β-NaYF4 core nanocrystals(NCs) with sub-10 nm size were synthesized with co-precipitation method, based on which the core-shell-shell structured NaYF4:Yb3+, Ln3+@NaYF4:Yb3+@NaYF4 NCs were constructed. The successfully growth of the middle active-shell and the outmost inert-shell were proved by XRD and TEM measurements. The spectral results indicated that partially isolate Yb3+ dopant in active-core and active-shell and the growth of the outmost inert-shell can effectively improve the upconversion(UC) emission intensity of Ho3+ and Tm3+, which is resulted from the enhanced absorption of 980 nm excitation light and energy transfer efficiency ascribing to the increased Yb3+ concentration quenching threshold. Moreover, through adjusting Yb3+ doping concentration in the middle-shell, the tunable emission can be obtained. This research suggested a general route for the development of highly-efficient luminescent upconversion nanocrystals(UCNCs) in a broad color range.关键词：upconversion;core-shell-shell structure;β-NaYF4288|112|1更新时间：2020-09-10
- 摘要：Single-band red upconversion emission has important applications for high-resolution biomarkers and 3-dimensional color display. However, the cross-relaxation of Ho3+/Ce3+ co-doping system normally yield the weak single-band red emission. In this paper, the dye-sensitized NaYF4:Yb/Ho/Ce(20%/2%/10%)@NaYF4:Nd(20%) nanoparticles were prepared to address such an issue. Highly uniform upconversion nanoparticles were prepared by solvothermal method, and the single-band red emission was obtained by increasing the Ce3+ doping concentration (from 0% to 10%) inside the core. When the near-infrared dyes of IR-806 were further conjugated, the upconversion luminescence intensity exhibited a 22-fold enhancement, and the red-to-green emission ratio also increased from 4.8 to 8.4. This paper provides a new way to improve the intensity and the purity of single-band red upconversion luminescence through dye sensitization, which is beneficial to high-resolution bioimaging.关键词：upconversion luminescence;single-band red emission;dye-sensitization;nanoparticles244|319|0更新时间：2020-09-10
- 摘要：As a new type of upconversion matrix, NaBiF4 has been found with excellent luminescence properties. In this paper, polyvinyl pyrrolidone(PVP) was used as the surfactant, and the water-soluble NaBiF4:Er3+/Yb3+/Mn2+ particles were successfully prepared by a solvothermal synthesis. The crystal phase, morphology and luminescence properties of the microcrystals were studied. Under the excitation of 980 nm laser, NaBiF4:Er3+/Yb3+/Mn2+ microcrystals show excellent upconversion luminescence(UCL). The upconversion emission intensity increased at first and then decreased with the increase of the dopant concentrations of Mn2+ ions. Moreover, the temperature-dependent UCL properties of NaBiF4:Yb3+/Er3+/Mn2+ were investigated systematically under 980 nm excitation. The microcrystals could be a potential candidate for sensitive temperature sensor.关键词：upconversion luminescence;NaBiF4;PVP surfactant;temperature-dependence225|238|0更新时间：2020-09-10
- 摘要：Mono-dispersed up-converting luminescent nanoparticles of NaYF4:20%Yb3+, 2%Er3+ with uniform size and morphology were prepared via the thermolysis method using rare earth chloride as the precursor. The crystal structure, morphology, and upconversion properties of the samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), energy dispersive spectrometer(EDS), X-ray photoelectron spectroscopy(XPS) and photoluminescence spectrum. The results show that the samples belong to the hexagonal system(space group:P6) and therefore verifies the phase purity of the samples. The sample exhibits the morphology of hexagonal disc with a diagonal length of about 77 nm and a thickness of about 54 nm. Under the excitation of 980 nm laser, the samples exhibit characteristic emission of Er3+ peaked at 523 nm(green), 542 nm(green) and 656 nm(red), which can be attributed to the transition from the level of 2H11/2, 4S3/2 and 4F9/2 to the level of 4I15/2, respectively. Both absorption of green and red were due to two-photon processes.关键词：thermolysis method;NaYF4:Yb3+, Er3+;nanoparticles;up-conversion luminescence;monodisper202|266|3更新时间：2020-09-10
- 摘要：Graphene oxide quantum dots(GQDs) were prepared by solvothermal method, using graphene oxide as a precursor. The solar cell devices were prepared by doping GQDs with different preparation conditions and mass fractions into poly 3-hexylthiophene and[6,6]-phenyl-C61-Methyl butyrate(PCBM:P3HT) as a sensitive layer. The experimental results show that when the sensitive layer is doped with GQDs of 0.2% mass fraction, the photoelectric conversion efficiency of solar cells is increased by 16.45% compared with that of undoped devices. When the sensitive layer is doped with GQDs prepared at a reaction time of 4 h and a temperature of 220℃, a sensitive layer film with low roughness and high ultraviolet visible light absorption strength is obtained. The photoelectric conversion efficiency of the prepared solar cells device was 1.34%, which was 12.60% higher than that of the undoped device. Therefore, suitable preparation conditions and doping concentration of GQDs can improve the photoelectric conversion efficiency of solar cell devices.关键词：graphene quantum dots;active layer P3HT:PCBM;polymer solar cells;surface roughness;UV-Vis absorption spectra206|286|2更新时间：2020-09-10
Synthesis and Properties of Materials
- 摘要：Optical loss reducing and brightness improvement are always attractive issues for light emitting diodes. In this paper, GaN based micro wheel light emitting devices(LED) are fabricated on silicon substrate by standard semiconductor technology. Isotropic wet etching process is applied to suspend the device thus optimize the device performance. Electroluminescence(EL) characteristics including the spectral intensity, full width at half maximum(FWHM), turn-on voltage and current induced wavelength shift, communication characteristics such as 3 dB bandwidth of two GaN micro wheels are studied and compared. Due to the reducing of optical loss, cavity effect is more obvious in the floating structure, and the improved EL and communication performance are obtained. The research in this paper is of great significance for the preparation of the electrically pumped light source and the visible light communication.关键词：light emitting diodes;GaN;micro wheel structures;3 dB bandwidth445|236|1更新时间：2020-09-10
- 摘要：ZnO UV photodetector is fabricated with the sandwich structure by radio frequency magnetron sputtering, based on the traditional metal semiconductor metal(MSM) single-layer ZnO UV photodetectors, another layer of ZnO film is laid to construct the sandwich device structure. At 5 V bias, the responsivity of the photodetector is 0.05 A/W, and the dark current is 1.44×10-5 A. The integrity of the device is significantly improved compared with the traditional single-layer ZnO UV photodetector. This is mainly due to the fact that the depletion region of the metal semiconductor contact can directly absorb the incident light, improve the absorption efficiency of the incident light, and avoid the shielding effect of the traditional upper electrode to the incident light.关键词：sandwich structure;ZnO UV photodetectors;responsivity287|303|1更新时间：2020-09-10
- 摘要：The demand for high peak power semiconductor laser arrays in high temperature working conditions is becoming more and more prominent. The high peak power 960 nm semiconductor laser arrays packaged by microchannel cooler were experimentally studied through the precision temperature control system. A series of output characteristics such as the peak power, power conversion efficiency, working voltage and spectrum are tested from 10℃ to 80℃, combined with theoretical analysis. The energy loss distribution of power conversion efficiency is given at different temperatures. The results show that the power conversion efficiency drops from 63.95% to 47.68% after the operating temperature increases from 10℃ to 80℃, and the proportion of carrier leakage losses increases from 1.93% to 14.85%, which is the main factor that causes the decline in the power conversion efficiency. This study has important guiding significance for high peak power semiconductor laser arrays in high temperature applications and laser chip design.关键词：high-power semiconductor laser array;high temperature;microchannel;power conversion efficiency;energy loss distribution253|182|3更新时间：2020-09-10
- 摘要：Microcrystalline Ga2O3 thin films were prepared on quartz substrates by radio frequency magnetron sputtering technology and thermal annealing technology. Using X-ray diffractometer(XRD), Raman spectroscopy, ultraviolet-visible-infrared spectrophotometer(UV-Vis-IR) and X-ray photoelectron spectrometer(XPS), the structure, optical properties and the chemical components were systematically studied. The results show that the prepared Ga2O3 film is amorphous. After the post-annealing process, all the films are changed from amorphous to microcrystalline films containing β-phase Ga2O3. With the rising of annealing temperature, the microcrystalline composition inside the film continues to increase. However, not all the thin films prepared on the quartz substrate were converted into fully crystalline thin films(β-Ga2O3). Based on amorphous and microcrystalline Ga2O3 thin films, metal-semiconductor-metal(MSM) structured solar blind deep ultraviolet photodetectors were fabricated. It was found that amorphous Ga2O3 thin film-based device shows higher optical response, while microcrystalline Ga2O3 thin film-based device shows lower dark current and faster response speed.关键词：gallium oxide;microcrystalline;photoelectric performance;olar blind UV photodetector282|254|1更新时间：2020-09-10
Device Fabrication and Physics
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