摘要：Metal halide perovskite quantum dots have the potential to become the next generation of luminescent display material because of their excellent optical properties such as high photoluminescence quantum yield， high color purity and adjustable band gap. At present， the electroluminescence efficiency of red-green perovskite quantum dot light-emitting diode （PQLED） has reached the level of organic light-emitting diodes （OLED）. However， organic long-chain ligands hinder charge transport， resulting in a lower brightness of perovskite quantum dot light-emitting diodes at maximum external quantum efficiency （EQE）. In order to realize that the perovskite QDs still have high luminescence brightness at the maximum EQE， we replaced the organic long-chain ligand with the inorganic ligand CaBr2， strengthened the carrier transmission in PQLED， and enhanced the electroluminescent carrier injection. Compared with organic long-chain ligand and organic short-chain ligand， inorganic ligand can slow down the electrical insulation caused by the existence of organic chains， improve the conductance of QDs， and further enhance the luminescence characteristics of QDs. Based on this strategy， we achieved perovskite quantum dot light-emitting diodes with a peak EQE of 10.57% at a high brightness of 3 753 cd/m2. At an operating voltage of 6.6 V， the maximum brightness of the PQLED is 116 612 cd/m2.
摘要：Materials that can emit light under mechanical stimulation can be called mechanoluminescent （ML） materials， and mechanoluminescence （ML） belongs to a mechanical-photonic conversion process. ML phenomenon was first observed in the early 17th century. However， it was not until the end of the 20th century that the emergence of SrAl2O4∶Eu2+ and ZnS∶Mn2+ ML materials and their excellent application prospects in the field of stress sensing attracted the attention of researchers again. In the past two decades， with the in-depth understanding of ML and the gradual mastery of ML performance enhancement methods， ML materials have been developed rapidly and have shown great potential for applications in the fields of anti-counterfeit encryption， stress sensing， disease monitoring， illumination display， and stress recording， etc. This paper focuses on the development and research status， and summarizes the classification， luminescence characteristics， luminescence mechanisms and application fields of ML materials. The current bottleneck problems and possible future research directions are proposed， aiming to provide useful inspiration for the development of new practical ML materials.
摘要：Achieving high luminous efficiency， high brightness and good thermal stability is an urgent requirement for solid-state lighting. Therefore， the high-performance color converters for high-power light-emitting diodes or laser diodes （LEDs/LDs） are significant to be explored. In this work， an effective strategy to improve the luminescent properties of YAG∶Ce color converters through method of component regulation was realized in YAG∶Ce transparent ceramic phosphors（TCPs） by incorporating Lu3+ ions. We prepared （Lu，Y）3Al5O12∶Ce TCPs（LuYAG∶Ce TCPs） with different Lu3+ contents by the solid-state reaction and vacuum sintering method. With the increase of Lu3+ content， the Y3+ sites in LuYAG∶Ce TCPs were substituted by Lu3+ sites， and the emission peaks of Ce3+ were blue-shifted from 573 nm to 563 nm. When the Lu3+ content was 60%， the emission intensity reached the maximum value and the luminous efficiency reached 114 lm∙W-1 by combining the LuYAG∶Ce TCPs with a blue LED. A 450 nm laser source was used to construct a laser-driven lighting device in a transmission mode. As the power density increased from 2.2 W·mm-2 to 39 W·mm-2， the luminous flux of the TCP with 60% Lu3+ substitution increased from 128 lm to 1 874 lm with no signs of luminescence saturation and the optimum luminous efficiency reached 128 lm·W-1. Thus， the LuYAG∶Ce TCPs are expected to be potential color conversion materials for high-power LEDs/LDs lighting.
摘要：A novel red fluoride phosphor BaTaF7∶Mn4+ was synthesized via the conventional co-precipitation method. The structure and luminescence properties of BaTaF7∶Mn4+ were investigated and discussed under various conditions. The BaTaF7∶Mn4+ phosphor shows strong ZPL emission intensity at about 630 nm under ultraviolet （UV） and blue light excitation. It originated from the highly distorted Mn4+ octahedral coordination environment in the C3v group symmetry. A warm LED fabricated with a blend of YAG∶Ce3+ and the BaTaF7∶Mn4+ phosphor showed excellent performance， indicating BaTaF7∶Mn4+ potential for application as a red phosphor for warm WLEDs.
摘要：Polyurethane materials have excellent mechanical properties， and luminescent self-healing polyurethanes have promising applications in areas such as crack self-diagnosis and repair. In this paper， a self-healing polyurethane （PUDS） with photoluminescent property was prepared by bonding bis（2-hydroxyethyl） disulfide （HEDS） and 1-（4-hydroxyphenyl）-1，2，2-tristyrene （TPE-OH） to a polyurethane system through chemical bonding， and its chemical structure was characterized by Fourier infrared spectroscopy. The aggregated structure， mechanical properties， self-healing properties and photoluminescence properties of PUDS were investigated in detail by X-ray diffraction， universal tensile tester， fluorescence spectrophotometer and other methods. The experimental results show that PUDS has excellent photoluminescence property， and its self-healing property and mechanical property are related to the dynamic disulfide bonding and hard segment content. With the increase of dynamic disulfide bonding， the self-healing property of materials gradually increases， but the mechanical property gradually decreases. With the increase of hard segment content， the self-healing property gradually decreases， but the mechanical property gradually increases. Therefore， the mechanical property and self-healing property of PUDS can be adjusted by changing the content of dynamic disulfide bonding and hard segment. In the work， the best self-healing property， mechanical property and photoluminescence property of the samples were obtained at 6.9%（wt） of dynamic disulfide bonding.
摘要：Mid-wavelength infrared （MWIR） optoelectronic devices can be used for various applications， including thermal imaging， optical communications， and gas sensing. Owing to the direct bandgap at all thicknesses and high carrier mobility， two-dimensional black phosphorus （BP） is promising for room-temperature mid-wavelength infrared optoelectronic applications. The intrinsic crystal anisotropy of such two-dimensional material also offers an exciting opportunity for the application in linear-polarization-sensitive photodetection. Furthermore， the electronic and optical properties of black phosphorus can be effectively modulated by doping， strain and fabrication of Van der Waals heterostructures， which is advantageous to meet the numerous demands for functional optoelectronic applications. Here we review the essential properties of two-dimensional black phosphorus and discuss the potential applications of black phosphorus in functional mid-wavelength infrared optoelectronic devices. Finally， some of the challenges and future outlooks of BP-based applications in mid-infrared optoelectronic devices are discussed and sug⁃ gested.
摘要：The on-chip integrated light source has always been a research hotspot in the field of optical communication. Indium phosphide （InP） material is an ideal material for constructing communication band light source. In this paper， InP-based microcavity light emitting devices are fabricated on InP substrate by standard semiconductor technology. By preparing four kinds of disk microcavity light emitting diodes， the influence of size on the performance of the device， including light intensity， full width at half maximum， center wavelength shift， etc. is investigated. This research may be of great significance for the preparation of electric-driven light source and the realization of optical communication in communication band.
摘要：As a new semiconductor material， metal halide perovskite （MHP） has shown excellent performance in photoelectric applications. Among them， MHP based light emitting diodes （PeLEDs） have developed rapidly， and the efficiency of red and green light devices has reached the commercial level. However， the efficiency of blue PeLED still lags far behind the counterparts， which largely hinders the application of PeLED in the field of full color display. In this paper， the blue-color quasi two-dimensional PeLED based on dimensional modulation is prepared by adjusting the proportion of mixed halogen anions and the composition of quasi two-dimensional perovskite. Firstly， we used the addition of phenylethylamine chloride （PEACl） to CsPbBr3∶PEABr quasi two-dimensional perovskite to gradually replace phenylethylamine bromide （PEABr）， and realized the modulated emission peak from 502 nm to 476 nm. However， with the increase of PEACl， the defects and n = 1 low-dimensional phase in thin films gradually increase， leading to a decrease of device efficiency. We introduced guanidine bromide （GABr） into CsPbBr3∶PEACl blue quasi-two-dimensional perovskite， and the n = 1 low-dimensional phase was significantly inhibited， which was conducive to exciton energy transfer， and finally the performance of quasi-two-dimensional PeLED was significantly improved in the range of blue light. This work provides a new approach for realizing efficient blue PeLED.
摘要：Nickel oxide （NiOx）， an inorganic p-type semiconductor， is commonly used as the hole transporting layer （HTL） for inverted perovskite solar cells （PSCs）. However， the high defect density of NiOx and mismatched energy levels with the perovskite layer strongly limit the efficiency of PSCs. In this work， the co-assembled monolayer is introduced to modify the interface of NiOx， which was demonstrated to passivate the defects and improve the energy level alignment， leading to the enhancement of charge extraction and transmission at the interface. Finally， the blade-coated PSCs yield a power conversion efficiency of 20.38% due to the improvement on open circuit voltage （Voc） and filling factor （FF）. Moreover， the device without encapsulation can maintain 96% of the initial efficiency after aging at 85 ℃ for 1 000 h in nitrogen atmosphere. More importantly， we have fabricated a perovskite solar module with an aperture area of 60.84 cm2， which is composed of 13 sub cells in series， and the efficiency has reached 17.04%.
关键词：Perovskite solar cells;module;bandgap alignment;charge extraction;high efficiency
摘要：Rare-earth doped laser glass fiber is the core gain medium of fiber laser.The concentration of the rare-earth ions is one of the important parameters to determine the gain characteristics of laser glass. How to determine the quenching concentration（QC） of laser glass quickly and effectively is a key scientific problem. In this paper， the QC of Er3+-doped germanate glass is predicted by using the spontaneous emission lifetime and the measured lifetime of the Er3+：4I13/2→4I15/2 transition. The results show that the maximum absolute error between the theoretical prediction and the actual value is less than 0.4%. Compared with the phenomenological model and finite diffusion model to determine the QC by fitting the luminescent intensity and measured lifetime of multiple experimental samples， our proposed method can determine the QC of laser glass by the test parameters of one or two samples， which is simple， fast and has little calculation error. It has a guiding significance for the research of high-gain laser glass and optical fiber.
摘要：There is a critical value of quenching concentration or optimal doping concentration in the laser glass due to the concentration quenching effect. It is particularly important to quickly and effectively determine the luminescent quenching concentration. In this paper， a semi-quantitative method is established for predicting the quenching concentration of laser glass by studying the relationship between the population of excited states of rare earth ions in glass and the doping concentration. It is found that the linear correlation between the transition rate of spontaneous emission and doping concentration is greater than its squared correlation with a concentration in Nd3+-doped phosphate glass. This indicates that OH- affects more to the transition probability of spontaneous emission than the energy transfer process between rare earth ions. The fluorescence lifetime at low concentration is selected instead of the spontaneous radiative lifetime to predict the quenching concentration， which effectively reduced the influence of multi-phonon relaxation and OH-， and the absolute error between the predicted luminescence quenching concentration and the experimental value was reduced from 0.82% to 0.16%. The proposed prediction calculation method has high accuracy and strong universality. This work guides determining the quenching concentration of laser glass and is beneficial to the research and exploration of a new type of laser glass.
摘要：Colloidal semiconductor nanocrystals present unique electronic and optical properties. The multiexcitons recombination process of semiconductor nanocrystals has attracted extensive attention motivated by the needs of prospective applications in lasing devices， light-emitting diodes， and photovoltaic cells. However， the reduction of particle size will accelerate the non-radiative Auger recombination of multiexcitons states， which significantly hinders the development of related applications. Therefore， suppressing Auger recombination has become an important research topic in the nanocrystal field. Increasing the volume of nanocrystals is considered to be an effective means to decrease Auger recombination. Here， we have synthesized a spherical quantum well structure CdS/CdSe/CdS by hot injection method. As a result of coherent strain， this sandwich like structure can diminish the strain on the interface which is caused by the material lattice mismatch， thus reducing dislocation defects and fabricating large-scale nanocrystals with quantum yield over 80%. By using time-resolved fluorescence spectroscopy， the multiexcitons recombination characteristics of large-scale quantum well are investigated in the fields of spectroscopy and dynamics. The decay lifetime and spectral characteristics of single exciton， biexcitons and high-order multiexcitons are analyzed， and the suppression effect on Auger non-radiative recombination of large-scale quantum well is confirmed. The study of multiexcitons recombination and Auger process in large-scale quantum well is expected to promote the development of nanostructures in multiexcitons applications.
摘要：Quantum dot color conversion （QDCC） is an effective strategy to realize the full color of new display devices and improve the display color gamut， but the poor environmental stability of QD limits its application and development. Based on the atomic layer deposition（ALD） process with self-limiting surface reaction characteristics， this paper explores the in⁃situ growth of dense alumina encapsulation film on a quantum-dot color conversion film （QDCCF）. This encapsulation method effectively combines a high light transmittance and high dense material with a tightly bonded process. The simulation results show that the light intensity of the QDCCF encapsulated by alumina reaches 94.9% of that of the unencapsulated one. Furthermore， the experimental results also show that the light transmittance of the substrate with alumina encapsulation is 96.4% of the blank substrate. Moreover， after working for 240 h in a high temperature and high humidity （85 ℃， 85% RH） environment， the light conversion efficiency of the encapsulated QDCCF remains 60.8% of the initial， which is 63.9% higher than the unencapsulated （11.43%）. The encapsulation method effectively improves the stability of QDCCF while the light intensity is not affected， which provides a feasible idea for improving the stability of QDCCF， and expands the application of ALD process in the field of photoelectric display， which has important scientific significance and application prospects.
关键词：alumina;atomic layer deposition;Quantum dot color conversion film;Light transmittance;stability
摘要：The thermal effect of OLED device was studied by PtOEP molecular temperature probe and different patterned OLED substrate， which was prepared with positive photosensitive polyimide （PSPI） and photolithography. The results show when the pixel size is less than 500 μm， the thermal effect is positively correlated with the pixel size， and independent of the line width and total opening area. However， when the pixel size reaches more than 500 μm， the thermal effect does not increase further. When 5 μm pixel works at a current density of 10 mA/cm2 at room temperature， the temperature of the device is 303.29 K. When the pixel size is 2 000 μm under the same conditions， the device temperature can reach 314.65 K. When the ambient temperature rises to 323.15 K， the thermal effect of the device shows the same trend. The EQE curves of devices with different thermal effects show that the increase of device temperature leads to the decrease of external quantum efficiency. The reason is that the increase of temperature improves carrier migration rate， but also increases the probability of collision between triplet excitons and between excitons and polarons， which leads to the exciton quenching and the decrease of efficiency.
关键词：Patterned OLED;PtOEP;Molecular temperature probe;junction temperature
摘要：AlN/Mo/Sc0.2Al0.8N composite structure films were prepared on Si（100） substrate by pulsed DC magnetron sputtering， and the epitaxy of GaN films was grown by metal-organic chemical vapor deposition（MOCVD）. Atomic force microscopy， high-resolution X-ray diffraction， powder X-ray diffraction， scanning electron microscopy and Raman spectroscopy were used to study the effect of the thickness of the Mo layer on the crystal quality of the Sc0.2Al0.8N layer and the GaN epitaxial layer， and the importance of the Sc0.2Al0.8N layer for the GaN epitaxial layer grown on Mo was also studied. The results show that the thickness of the Mo layer is an important factor affecting the Sc0.2Al0.8N layer and the GaN epitaxial layer， and the Sc0.2Al0.8N layer is of great significance to the epitaxy of GaN on Mo. When the thickness of the Mo layer is 400 nm， the crystal quality of the GaN epitaxial layer is the best， the full width at half maximum of the X-ray diffraction on the GaN（002） surface is 0.51°， and the compressive stress calculated by Raman spectroscopy is 483.09 MPa.
关键词：GaN;metal-organic chemical vapor deposition（MOCVD）;ScAlN;X-ray diffraction（XRD）
摘要：The arrival of the era of big data and the Internet of Things makes the traditional Von Neumann architecture computer face great challenges in the process of data processing. The architecture of storage and computing separation fundamentally limits the computing speed and energy efficiency of the computer. It is urgent to develop a new computing paradigm to overcome the current challenges. Neuromorphic computing has attracted wide attention because of its high parallelism， low power consumption and integrated storage， and the novel neuromorphic devices with unique physical mechanisms are the basic units of neuromorphic computing systems. Among many candidate materials， low-dimensional materials have unique physical and electrical properties. Weak interlayer Van der Waals forces enable them to be arbitrarily stacked， which is conducive to heterogeneous integration. In this paper， the research progress of artificial synaptic devices and artificial neural devices based on low-dimensional materials is reviewed. The working mechanisms， performance indicators and technical advantages of different types of neuromorphic devices are summarized. On this basis， the applications of neuromorphic devices based on low-dimensional materials in the fields of vision， hearing， motion control and large-scale integration are introduced. Finally， the future development of artificial neuromorphic devices is analyzed and prospected.
摘要：With the spread of bacterial drug resistance， especially the emergence of “superbugs”， it's an urgent need to develop new antibacterial materials and technologies with high efficiency， low toxicity and no drug resistance. In this study， thea viridis derived carbon dots （T-CDs） were successfully prepared by solvothermal method. Under 660 nm laser irradiation， the prepared T-CDs could effectively produce reactive oxygen species （ROS）. In vitro and in vivo experiments showed that T-CDs have excellent biocompatibility， and can produce ROS under laser irradiation to kill methicillin-resistant Staphylococcus aureus， thereby reducing wound inflammation caused by bacteria and accelerating wound healing. The prepared T-CDs can kill pathogenic bacteria through PDT and promote the healing of infected wounds， provide a new idea for the development of antibiotic replacement drugs， and have important value for exploring new clinical treatment schemes of drug-resistant bacteria infected wounds.