摘要:When it mentions phosphor-converted(PC) light source, people would think of white or near-infrared light sources. In contrast, attention on the PC light sources at the other end of the spectrum-the shorter-wavelength ultraviolet region is absent. Taking into account the potential applications of ultraviolet light, the investigation of PC design as an alternative ultraviolet light source will be interesting. Here we introduce a concept of ultraviolet PC light source, in which the ultraviolet emission can be achieved upon a blue-light upconversion excitation. As a proof of concept, we demonstrate the PC design using an ultraviolet-B phosphor, Lu2Pr0.01Gd0.99Al2Ga3O12. Upconversion emission at 313 nm appears from the phosphor upon illumination with a 450 nm laser. Subsequently, we prepare a composite film using the phosphor, and build a transmissive remote phosphor light source. According to the emission and excitation features of the PC light source, we present an ultraviolet imaging demonstration. This study brings the PC light source to the ultraviolet region, which may offer a unique opportunity for some applications of optical tagging or indicator in bright environments.
关键词:phosphor-converted(PC);pc ultraviolet light source;upconversion of Pr3+;emission of Gd3+;phosphor composition film
摘要:Mechanoluminescent(ML) materials have extensively applications in stress sensing, optical information storage, bioimaging display, anti-counterfeiting and other fields. Thus, they have drawn increasing attention of the researchers over the world. Up to now, the development of ML materials has mostly focused on the visible range, which greatly limited the relative applications and development. Near-infrared(NIR) ML materials can avoid the interference of ambient light and have good biological tissue permeability, which gradually attract the attention of researchers and have become an important class of ML materials. This paper mainly discusses on the emission mechanism and current progress of NIR ML materials, and proposes prospects for their future research directions.
摘要:Direct current driven green transparent organic light-emitting device utilizing transparent Mg:Ag cathode was fabricated. Then, novel device structure employing transparent Mg:Ag interconnecting layer to connect two light-emitting units was proposed to realize alternating current driven green transparent organic light-emitting device(AC-TOLED). The spectra of AC-TOLED were almost identical in the direction of light output on indium tin oxide(ITO) and Mg:Ag sides. The maximum brightness was 1 374 cd/m2 and 283 cd/m2, respectively. And the maximum efficiency was 26.1 cd/A(8.1 lm/W) and 3.5 cd/A(1.7 lm/W), respectively. The higher performance of ITO side was caused by the different transmission of ITO electrode and Mg:Ag interconnecting layer. Under low frequency alternating current, the two light-emitting units of AC-TOLED emitted green light alternately. However, the two light-emitting units of AC-TOLED emitted green light simultaneously for human eyes under high frequency alternating current, because human eyes cannot distinguish the flicker of each unit during alternative emission.
关键词:alternating current driven;transparent;organic light-emitting device
摘要:Novel Dy3+ doped LaF3 crystals is synthesized by multi-crucible temperature gradient technology(MC-TGT). The crystallographic sites concentration is up to 5.90×1020 ions·cm-3 for 2%Dy:LaF3 following the segregation coefficient of 0.8 measured by inductively coupled plasma emission spectrometer. The photoluminescence spectra of 1%Dy:LaF3 show the strongest wavelength peaked at 601 nm and the widest wavelength band centering at 511 nm under excitation wavelength of 400 nm. By changing the excitation wavelength to 450 nm, the strongest wavelength shifts to 677 nm and the widest wavelength band shifts to 568 nm in 1%Dy:LaF3, respectively. In the case of 2%Dy:LaF3, two main central wavelengths at 478 nm and 571 nm are observed under excitation wavelength of 400 nm or 450 nm. The optical quality of as-grown Dy3+:LaF3 crystal is characterized by transmission spectra at the range of 2.5-11 μm. The optical transmission of Dy:LaF3 crystal with thickness of 0.96 mm reaches over 85%, indicating a high-optical quality in the range of 2.5-9 μm. Thus, Dy:LaF3 has great application potentials in visible and mid-infrared laser.
摘要:In recent years, antimonide type-Ⅱ superlattices have a great progress in the epitaxial growth and luminescence property research, which has laid an important foundation for the research of high-performance middle infrared band optoelectronic devices. However, due to the existence of intrinsic Ga atomic defects, the traditional InAs/GaSb system superlattice materials make the minority life of InAs/GaSb materials too short, which seriously affects the performance improvement of optoelectronic devices. Therefore, it is of great significance to design and grow new material system superlattice materials with long minor carrier lifetime. This paper summarizes and analyzes the various materials systems of antimonide type-Ⅱ superlattice materials at present, emphasizes the development of epitaxial growth conditions, structure and optical properties of various material systems, and gives a prospect for the future development of antimonide type-Ⅱ superlattice materials.
摘要:It was well known that 2% Er3+ of the doping concentration is optimal in the fluorides nanostructures co-doped with Yb3+ and Er3+ for boosting upconversion luminescence. Herein, a series of NaYb1-xF4:Erx3+ upconversion nanoparticles were synthesized with different Er3+/Yb3+ doping ratio, which were analyzed and characterized by SEM, XRD and spectroscopy. It was shown that the two doping ratio of Er3+/Yb3+, i. e. 0.02/0.98 and 0.4/0.6, are the most favorable for upconversion luminescence of the as-synthesized nanoparticles. The XRD reveals that the as-synthesized series of nanoparticles show three phase structures, one α phase for 0.02/0.98~0.2/0.8 of the Er3+/Yb3+ doping ratios, i.e. the other β phase for 0.6/0.4~0.8/0.2, and the third coexisting phase consisting of α phase and β phase for 0.3/0.7~0.4/0.6, respectively. These results can be useful in promoting the development of biomedical, solar and laser applications.
关键词:fluoride nanoparticles;co-doping with Yb3+ and Er3+;optimal concentration ratio;phase transition;upconversion luminescence
摘要:In this paper, Ag, PMMA and perovskite CsPbBr3 films have been integrated into a plane waveguides to explore the optical physical mechanism and new application of plasmon structure. It is shown that the localized field on the Ag/perovskite CsPbBr3 interface has been increased giving rise to PL and radiative ratio(Γ=τ-1) enhancement of CsPbBr3 excitons as varying system structures, especially modifying the thickness of PMMA. Decay curves have been fitted by both two exponential and ensemble stretched functions, respectively. It is found that there is big fitting discrepancy. Without considering the localized field enhancement on the Ag/CsPbBr3 interface, the fit results(τavg, 30~25 ns) by two exponential form are similar to the results in free space reported previously. The PL lifetime shortening(τavg, 12~9 ns), or radiative rate increasing have been found by the latter fitting. The above-mentioned investigations can provide the basis for optical physical fundamental research and design and developing of surface plasmon polaritons(SPPs) luminescence-display devices.
关键词:perovskite CsPbBr3;surface plasmon;optical waveguide;enhancement of localized field
摘要:The MgZnO film was grown on the sapphire substrate by the metal organic compound chemical vapor deposition(MOCVD) method. Combined with photolithography and polystyrene(PS) microsphere template technology, the MgZnO ultraviolet detector based on the Ag microporous array electrode structure was fabricated.Compared with devices based on conventional metal film electrodes, the photocurrent of the MgZnO ultraviolet detector based on the microporous array interdigital electrode is increased by nearly 6 times, while its dark current and response time remain basically unchanged. Through the characterization of ultraviolet-visible transmission spectra and electrical properties, the mechanism of the influence of the microporous array structure Ag electrode on the UV photodetection performance of the MgZnO film was discussed. This study provides a feasible way to prepare high-performance UV detectors.
摘要:Owing to the unique properties, In2O3 nanowires have become potential candidates for ultraviolet photodetectors. To date, In2O3 nanowires-based UV photodetectors have been extensively studied. However, the large dark current limits its further applications. In this paper, a single In2O3 nanowire ultraviolet phototransistor is performed. Through the modulation of the back gate voltage, the dark current is almost completely depleted. At the same time, the threshold voltage shows a shift under illumination, leading to little dependence between gate voltage and photocurrent. Finally, a single In2O3 nanowire ultraviolet phototransistor with a high optical on-off ratio of 1.07×108 and a high responsivity of 5.58×107 A/W was obtained, which is better than the previously reported In2O3 nanostructured optoelectronic devices. This work promotes the application of In2O3 nanowires in the next generation of nano-optoelectronic devices and integrated circuits.
摘要:In this paper, an ion implantation process is used to form a high-resistance isolation region on the p-GaN layer of the InGaN/GaN quantum well blue LED structure. This method has been used to realize the preparation of ultra-small size and high luminous efficiency Micro-LED arrays with a minimum size of 4 μm. The electrical and optical properties of lateral structure Micro-LED arrays prepared by fluoride ion implantation isolation process are systematically studied. Experimental results show that higher fluoride ion implantation energy can improve opticlal and electrical isolation between Miro-LEDs. When the ion implantation energy is 60 keV, the Micro-LED array has the relatively best photoelectric effect. And the 4 μm ultra-small size Micro-LED array prepared based on this ion implantation energy has an optical power density of up to 200 W/cm2, demonstrating the application potential of ion implantation technology in a new generation of Micro-LED based micro-display chips.
关键词:blue micro-LED;ion implantation isolation;GaN;lateral structure;high optical power density
摘要:Due to the better beam quality, horizontal cavity surface emitting distributed feedback(SE-DFB) semiconductor lasers have received widespread attention. In this paper, a horizontal cavity surface emitting distributed feedback semiconductor laser with a wavelength of 940 nm was designed. This paper analyzed the influence of the structure parameters of the grating(shape, period, duty cycle, etched depth, etc.) on the optical characteristics of the laser(linewidth, side-mode suppression ratio, power and slope efficiency, etc.). Combined with the fabrication of second-order grating, ridge-shaped waveguide, electrode and light exiting, as well as cleavage and encapsulation technology, the device with optical wavelength of 940.3 nm is prepared. The line width of the device is 0.52 nm, and the surface emission power is 890 mW under continuous operation mode.
摘要:Based on a new composite interface transport layer, large-area organic solar cell module was fabricated by vacuum evaporation of organic small molecular materials. According to the transmittance spectrum, surface roughness morphology and surface wettability of transport layer, the surface roughness of active layers based on different substrates, the uniformity of blade coating and the influence of different transport layers on the performance of organic solar cells were analyzed. The experimental results show that when the electronic dense layer of 4, 7-diphenyl-1, 10-phenanthroline(BPhen) acetylimide is deposited on the surface of aluminum-doped zinc oxide substrate, the new composite transport layer is formed, which does not affect the light transmittance of the substrate in the range of 300-900 nm. In addition, the electron dense layer of BPhen can effectively improve the flatness and wettability of the substrate surface, which is beneficial to the subsequent scraping of the active layer solution and improves the quality and the stability of the coating film. By analyzing the surface roughness and three-dimensional morphology of the active layer film coated on different substrates, the surface roughness of the active layer film coated on the AZO(Al doped ZnO)/BPhen new composite transport layer was significantly reduced. It means that the new composite transport layer as substrate is beneficial to scrape out a uniform active layer film. As a result, the open circuit voltage(Voc), short-circuit current density(Jsc) and fill factor(FF) of rigid and flexible module device are significantly improved, and the power conversion efficiency(PCE) of the new rigid modular device is increased to 10.62%, which is about 13% higher than stand device. Importantly, the PCE of the flexible module device reaches 5.13%, which is also approximately 32% higher than AZO-based device.
关键词:new composite transport layer;organic solar cell module;electron dense layer
摘要:The photomultiplication(PM)-type organic photodetectors(OPDs) with the structures of ITO/ZnO/P3HT:IEICO/Al and ITO/PEDOT:PSS/P3HT:IEICO/Al are fabricated by solution-processing method, respectively. In the active layers, the weight ratio of electron donor and acceptor is 100:1. The OPDs based on a ZnO interfacial layer can work well both under forward and reverse bias voltages, while the OPDs based on a PEDOT:PSS interfacial layer can only work under reverse bias voltages. Under -15 V bias, compared with the PEDOT:PSS interfacial layer-based OPDs, the ZnO interlayer-based OPDs exhibit a more than 4 times smaller dark current density(2.2 μA/cm2), a more than 3 times larger light current density(3.7 mA/cm2) under 1.5 mW/cm2 light illumination, and more than 4 times larger average external quantum efficiency(3262%) and responsivity(13.3 A/W) with a more than 11 times larger average detectivity(1.6×1013 Jones). These results demonstrate that the ZnO interfacial layer can reduce the dark current density and increase the EQEs of PM-type OPDs significantly, all of which can greatly improve the optoelectronic performance of devices.
摘要:In recent years, two-dimensional materials(2D materials) based synaptic transistor devices have attracted extensive attention due to their low dimension, simultaneous read-write operation and high efficiency. However, the process compatibility, repeatability and complex transfer process of these materials are still a great challenge. In this work, a simple dip-coating method was utilized to realize a synaptic transistor with an ultra-thin indium gallium zinc oxide(In-Ga-Zn-O, IGZO) semiconductor layer(less than 8 nm). The operating voltage was as low as 3 V. The important biological synaptic behaviors were successfully simulated, including excitatory post-synaptic current(EPSC), paired pulse facilitation(PPF), and long-term potentiation(LTP). Under ultra-thin condition, due to the enhancement effect of defects and the improvement of the controllability of ultra-thin active layer by gate voltage, the memory retention ability of our synaptic transistor is improved. Our work proposed a way to improve the long-term characteristics of synaptic transistors, and provided a simple and easy method for the preparation of high-performance ultra-thin synaptic transistors using common materials.
关键词:ultra-thin;metal-oxide thin film transistor;synapse
摘要:Since the graphene was found, with the continuous research and exploration by people, more and more two-dimensional materials with similar structures have been discovered and studied successively due to their excellent photoelectrical properties. The widespread attention is paid to the transition metal dichaldogenides(TMDs) due to their rich physical properties. This paper researches the two-dimensional three-layer WSe2 photoelectric property, and transfers it to the Au electrode of SiO2/Si substrate by Van Der Waals force. Finally, the silver paste is used to extract the back gate electrode with WSe2 field effect transistor manufactured, whose carrier mobility is 3.42 cm2/(V·s). The detector response ratio of the WSe2 field effect transistor based on the 630 nm wavelength is 0.61 A/W and the light response recovery time is 1 900 ms.
关键词:two-dimensional semiconductor materials;transition metal dichaldogenides(TMDs);WSe2;photoelectric detection
摘要:Perovskite solar cells can be constructed as semi-transparent due to the materials' unique optical properties, which can be applied as the building integrated photovoltaic aiming to solar energy collection. Based on the latest research progress of photovoltaic smart window, this paper summarizes the main methods of perovskite solar cells applied to green building smart windows and the main technologies to realize the transparency of perovskite solar cells, and predicts the transparency and efficiency of the application of perovskite solar cells in smart windows. In addition, a random sampling method is used to conduct user surveys, analyzing the costs and benefits of photovoltaic windows, and prospecting for their commercial applications.
关键词:perovskite;smart windows;semi-transparent solar cells;cost-benefit