YAN Yinguo,CAI Junhu,ZHOU Xiaojian,CHEN Enguo,XU Sheng,YE Yun,GUO Tailiang
Corrected Proof
DOI:10.37188/CJL.20230012
Abstract: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 hours in a high temperature and high humidity (85 °C and 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.
Keywords:alumina;atomic layer deposition;Quantum dot color conversion film;Light transmittance;Stability.
Abstract: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 demand 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 suggested.
Abstract: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.
Abstract:Glass ceramics embedded with only one kind of nanocrystals are usually cannot meet the requirements of multi-color, multi-mode and ultra-wideband luminescence applications due to the limitation of single crystal field environment. It is thus of significant to develop dual-phase nanocrystal-based glass ceramics for expanding the application field of this kind of functional materials. In this paper, an aluminosilicate glass ceramic containing α-Zn2SiO4 and β-Zn2SiO4 nanocrystals was successfully prepared by a melt quenching technique. The transition from single-phase to dual-phase nanocrystals can be achieved by varying Al2O3 content and heat treatment temperature. The obtained glass ceramics exhibit tunable single-band (~580 nm) and continuous dual-mode (~530/580 nm) emission under the excitation of 285 nm, and the luminescence intensity varies with the concentration of Mn2+ and heat treatment temperature, resulting in a tunable emissive color from orange to yellowish. The related luminescence mechanism was explained by combining with the structure of nanocrystals and spectral data. This research may be of reference value for the preparation of dual-phase glass ceramics and exploration of broadband light source.
LI MENG,SUN Yang,JI Xin,GAO Fei,QIN Feifei,ZHU Gangyi
Corrected Proof
DOI:10.37188/CJL.20220434
Abstract:The on-chip integrated light source of light source has always been a research hotspot in the field of optical communication. InP material is an ideal material for constructing communication band light source. In this paper, InP-based microcavity light emitting devices are fabricated on indium phosphide (InP) substrate by standard semiconductor technology. By preparing four kinds of disk microcavity light emitting diodes (LED), the influence of size on the performance of the device, including light intensity, full width at half maximum (FWHM), center wavelength shift, etc. This research may be of great significance for the preparation of electric-driven light source and the realization of optical communication in communication band.
Abstract: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 germanateglass 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 wt.%.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.
Abstract: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 has 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 3753 cd/m2. At an operating voltage of 6.6 V, the maximum brightness of the PQLED is 116612 cd/m2.
Abstract: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 TCPs by incorporating Lu3+ ions. We prepared (Lu,Y)3Al5O12:Ce transparent ceramic phosphors (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 to 563 nm. When the Lu3+ content was 60 at.%, 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 to 39 W·mm-2, the luminous flux of the TCP with 60 at.% Lu3+ substitution increased from 128 to 1874 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.
Abstract: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 lifetimes 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.
Abstract: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. The authors 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.
Abstract: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°C for 1000h 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%.
Keywords:Perovskite solar cells;module;bandgap alignment;charge extraction;high efficiency
LI Zi-xin,HUANG Han-jun,YOU Somary,MENG Jian-wei,WANG Lei,XIAO Li-bai,REN Xiang-kui
Corrected Proof
DOI:10.37188/CJL.20230005
Abstract: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.
SONG hong-wei,ZHOU dong-lei,BAI xue,XU wen,DONG biao,XU lin
Corrected Proof
DOI:10.37188/CJL.20220391
Abstract:Lead halide perovskite, as a new class of optoelectronic materials, has demonstrated excellent optical and electrical properties, extensive and important applications in solar cells, light-emitting diodes, photodetectors, lasers and so on, attracting great attention. Rare earth is a special kind of material in the periodic table of elements,ranging the elements from 57 to 71, with 4fn and 4fn-15d electronic configurations. What kind of new baby will be born if rare earth combines with perovskite materials and devices? This paper aims to combine the author's work and experience in related fields, briefly review the progress made in this field in recent years, and search for the problems and challenges faced in the future. This article is not to summarize the complex individual phenomenon to be brief, but to explore the common problems of universal significance for the purpose. In the selection of data and information, it may be biased, and there is a serious suspicion of "Every potter praises his pot", please think carefully.
KONG Jun-Ren,YANG ZHOU,ZHANG Shi-Rui,LI Rui-xin,WANG Xiao-Ming,JIAO Huan
Corrected Proof
DOI:10.37188/CJL.20220411
Abstract: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.
Li Jia-hao,HAN Jun,Xing Yan-hui,Dong Sheng-yuan,Wang Bing-hui,Ren Jian-hua,Zeng Zhong-ming,Zhang Bao-shun,Deng Xu-guang
Corrected Proof
DOI:10.37188/CJL.20220406
Abstract: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.
Abstract: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 303.29K.When the pixel size is 2000 μm under the same conditions, the device temperature can reach 314.65K.When the ambient temperature rises to 323.15K, 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.
Keywords:Patterned OLED;PtOEP;Molecular temperature probe;junction temperature
Abstract:Rare-earth-doped laser glass is the key medium of fiber lasers. However, how to predict the spectroscopic properties quantitatively remains a challenge to accelerate the development of high-performance laser glasses. Here we regard the nearest-neighboring congruently melting compound(CMC)as the component and structural “motif” of glass based on the phase diagram model and apply it to the Tm3+-doped binary germanate laser glass systems. The experimental properties of Tm3+-doped glassy CMCs are utilized to calculate and predict the physical and spectroscopic properties, such as density, refractive index, effective linewidth, absorption/emission cross-sections, radiation lifetime, etc., of germanate laser glasses by utilizing the leverage rule. The results illustrate that the predicted physical and spectroscopic properties are in good agreement with the experimental values, with the maximum absolute errors of less than 4.61% and 9.66%, respectively. Moreover, the phase diagram approach can capture the trends of physical and spectroscopic properties as a function of composition, including the linearly or germanate-anomaly compositional dependence, which provides an opportunity to decipher the composition-structure-property relationships of laser glasses. This study is expected to shed light on the property prediction and composition design of laser glasses.
Keywords:laser glass;spectroscopic properties;quantitative prediction;phase diagram model
Abstract:In this paper, Ga2O3 thin film was grown on c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD), and then asymmetric electrodes were fabricated on the surface of Ga2O3 thin film by photolithography, lift-off, and electron beam evaporation. Pt/Au was used as the Schottky electrode, and Ti/Al/Ni/Au was used as the Ohmic electrode; in order to achieve good Ohmic contact and improve the injection efficiency of interface carriers, the corresponding annealing treatment is carried out. The relevant results show that the Pt/β-Ga2O3 Schottky photodiode has a good level of deep ultraviolet detection. At -5 V bias, the responsivity and external quantum efficiency was 3.4 A/W and 1.66×103%, respectively. The detectivity was up to 1013 Jones, indicating that it has excellent weak signal detection capability. At the same time, the responsivity and external quantum efficiency decrease with the increase of light intensity, which is due to the higher concentration of photogenerated carriers, which improves the recombination probability of electron-hole pairs. In self-powered mode, the Pt/β-Ga2O3 Schottky photodiode exhibited a fast responsivity of 2.69 mA/W. In addition, the detector can still operate stably under high voltage of -100 V and +100 V, indicating that the detector has good stability against high voltage operation.
HU Gang-jian,CHEN Qi,WEI Wei,SUN Zai-Cheng,YAO Meng-nan,SHEN Liang
Corrected Proof
DOI:10.37188/CJL.20220399
Abstract:X-ray detection plays an essential role in areas such as medical imaging, determination of specific crystal structures, and radio astronomy. However, traditional materials used in the field of X-ray detection, such as silicon and cadmium antimonide, suffer from complex fabrication processes, excessive cost and low sensitivity to X-rays, which severely limit the development of the field. As a hot topic in recent years, lead halide perovskites have shown excellent performance in the field of X-ray detection due to their large atomic numbers and elevated absorption coefficients. While the perovskite material system is a huge family, different components of perovskite materials have their advantages and disadvantages, and even the same component of perovskite material can have different properties depending on different parameters such as crystallization. In this paper, we review recent achievements in direct-conversion perovskite X-ray detectors from the perspective of perovskite material regulation and provide an outlook on future developments in perovskite X-ray detection.
Keywords:Perovskite;material regulation;direct type;X ray detection
Abstract:The preparation of purple-emissive carbon dots (P-CDs) usually accompanies the disadvantages of complicated preparation, low quantum yield (QY) and low fluorescence intensity. Herein, we used o-phenylenediamine (OPD) and m-phenylenediamine (MPD) as nitrogen sources and citric acid (CA) as carbon source to prepare P-CDs. Only using simple one-step hydrothermal method under a low experimental temperature of 120 ℃, we successfully obtained highly luminescent P-CDs with absolute QY of 5.3%. The results of XPS and FT-IR revealed that all synthesized P-CDs contained similar functional groups but with different contents. The fluorescence intensity of P-CDs could be effectively regulated by the amount ratio of OPD to MPD. The resulting P-CDs also possessed considerable photostability and salt stability. Notably, the fluorescence color of P-CDs remarkably transformed into green as the pH being in the range of 1-3 or 10-13. The aforementioned unique pH-dependent fluorescence chromic behaviors ensured the potential application in the optical pH sensing.