摘要:Photothermal therapy(PTT) is developing rapidly in the field of antitumor therapy, due to its non-invasiveness, spatiotemporal controllability, and high efficiency. However, there are some practical problems in PTT, which hinder its further transition from basic scientific research to clinical applications. Herein, at first, this review briefly introduces the photothermal conversion principle and antitumor mechanism of PTT. Then, the main problems in the development of PTT are summarized, and those corresponding solutions are listed, including: enhancing the photothermal conversion efficiency by the control of nanomaterial morphology, the construction of heterojunction structures, and the adjustment of optical windows; overcoming the limitation of single PTT by the invention of collaborative treatment models; consolidating antitumor therapy effect by increasing tumor enrichment of nanomaterials; improving the biological safety of nanomedicine by the design of tumor microenvironment-activated photothermal complex and the realization of mild PTT. Finally, the future prospect and development of PTT are stated.
摘要:X-ray detection is widely used in medical diagnosis, industrial flaw detection, security and other fields, and X-ray array detector is the key part of imaging equipment. High spatial resolution can be achieved by converting X-ray into electrical signals in one step using semiconductor materials. Perovskite material has become the star material of direct X-ray detector in recent years due to its advantages of high X-ray decay ordinal number, long carrier diffusion distance and irradiation stability. This paper briefly introduces the principle, critical nature and core materials of the direct type of X-ray detection, indicates the advantages of halide perovskite in applying in direct X-ray detector and expounds the characteristics and the latest research progress of both perovskite single pixel detector and TFT integrated array detector. Finally, the current technical challenges and potential solutions are put forward, and the future development trend of X-ray detector based on halide perovskite is prospected.
关键词:X-ray imaging;perovskite;array detector;Integrated with TFT
摘要:Pure organic room temperature phosphorescence materials have become a research hotshots in the field of functional materials because of their low cost and easy regulation of performance. In this work, the development of pure organic room temperature phosphorescence materials in recent years is introduced in detail. The pure organic small molecular crystals, polymers and intelligent room temperature phosphorescence materials were systematically summarized. Finally, the effective strategies of realizing organic phosphorescence in room temperature atmosphere are summarized.
关键词:pure organic materials;room temperature phosphorescence;afterglow;crystal;polymer;smart materials
摘要:NaBaPO4∶Er3+ was synthesized by solid-state reaction. Ag nanoparticles(NPs)(including Ag ball and Ag cube) were synthesized by chemical reduction method. The surface plasmon resonance of Ag NPs was utilized to enhance the multi-photon near infrared(NIR) quantum cutting emission intensity under multi-excitation. The surface plasmon resonance of Ag ball NPs was utilized to enhance the NIR emission intensity of four-photon and three-photon under the excitation of 377 nm and 485 nm, respectively. The surface plasmon resonance of Ag cube NPs was utilized to enhance three-photon NIR emission intensity under the excitation of 377 nm.
摘要:Currently, the use of a blue LED chip in conjunction with the yellow-emitting YAG∶Ce3+ phosphor is recognized as the main approach for achieving high-brightness white light. However, due to the spectrum defect of the long-wavelength component, this approach has resulted in a poor color rendering performance of LED lighting devices. Thus, the luminescent materials with long-wavelength emission(> 600 nm) are very important for high quality LED lighting devices. In order to develop Ce3+ doped luminescent materials with long-wavelength emission, the effect of coordination structure on the band/electronic structures of Ce3+ needs to be further studied. In this paper, based on the first-principles calculation, the crystal and band/electronic structures of Y2Si3N4O3∶Ce3+, Y4Si2N2O7∶Ce3+, and Y3Si5N9O∶Ce3+ luminescent materials in Y-Si-O-N system were studied by using the density-functional theory(DFT) of the generalized gradient approximation(GGA). To understand the relationship between band/electronic structures and the luminescence properties of Ce3+, the emission and excitation spectra of these luminescent materials were also studied. According to the research conclusions, the oxynitride structures with higher nitrogen content, shorter Ce—N bond lengths, and lower point symmetry coordination structure are suitable for the development of Ce3+ doped luminescent materials willing to achieve long-wavelength emission.
摘要:Tb3Sc2Al3O12(TSAG) crystal is attracting much attention for visible and near-infrared isolator applications due to its high transmittance, large laser damage threshold, low absorption coefficient and excellent magneto-optical properties. However, it is difficult to grow large-size crack-free single crystals. In this work,high quality TSAG crystal was successfully grown by the Czochralski method. The transmittance in the wavelength of 400-1 500 nm is as high as 84%. The thermal conductivity is higher than that of commercial Tb3Ga5O12(TGG) crystal. More importantly, the Verdent constant of TSAG is 1.2 times that of TGG crystal. Therefore, TSAG crystal is promising magneto-optical crystal for high power isolator applications.
摘要:White light emitting diodes(LEDs) are widely used in solid state lighting, and blue phosphors play an important role, which has become the focus of current research. In this work, KYBaSi2O7∶Bi3+ blue phosphor was synthesized by the high temperature solid-state method, and the luminescence properties of the phosphor were studied. The results show that the blue phosphor KYBaSi2O7∶Bi3+ exhibits an asymmetric emission band, which can range from 380 nm to 600 nm, and the peak locates at 418 nm. There is the concentration quenching of Bi3+ in KYBaSi2O7. The phosphor shows the good thermal stability, and the emission at 400 K remains the 64% of the original intensity. The white LED was synthesized by combining commercial phosphor with 370 nm near-UV LED chip. The chromatic coordinates of white light were (0.368 2, 0.398 1) and the color temperature was 4 463 K.
摘要:Gd2(1-x)Eu2xWO6(0≤x≤0.35), Gd2(1-y)Eu2yMoO6(0≤y≤0.25) and Gd1.9Eu0.1WzMo(1-z)O6(0≤ z≤1) series of red phosphor were prepared by high temperature solid-state reaction method. The optimum synthesis temperature and the optimum doping concentration of Eu3+ in Gd2(1-x)Eu2xWO6 and Gd2(1-y)Eu2yMoO6 phosphors were explored. The effects of W6+ and Mo6+ ratio on Gd1.9Eu0.1WzMo1-zO6 phosphors were further explored. In Gd2(1-x)Eu2xWO6 and Gd2(1-y)Eu2yMoO6 phosphors, the diffraction peaks moved to small angle with the Eu3+ concentration increasing. The luminescence concentration quenching mechanisms of Eu3+ in Gd2(1-x)Eu2xWO6 were studied. With the content of Mo6+ increasing, the red-shift of the charge transfer band was observed in Gd1.9Eu0.1WzMo(1-z)O6 phosphors. The values of energy band gaps of some phosphors were calculated based on diffuse reflectance spectra. The morphologies and the compositions of some phosphors were characterized by field emission scanning electron microscope and energy disperse spectroscopy.
关键词:high temperature solid state reaction method;phosphors;photoluminescence;concentration quenching;red shift
摘要:In this paper, β-Ga2O3 bulk films were prepared by high-temperature thermal oxidation of p-type gallium arsenide (p-GaAs) single crystal substrate. The effect of O2 flow rate on the morphology of β-Ga2O3 bulk films was also discussed. By testing and analysing the crystal quality, structural characteristics and photoluminescence characteristics of the bulk films, we found that the transformation of GaAs into β-Ga2O3 bulk films was related to Langmuir evaporation. When the O2 flow rate was low(0.2 L/min), GaAs substrate was in anoxic state, and the prepared samples showed nanolinear morphology. However, when the flow rate of O2 exceeds 0.4 L/min, GaAs substrate is completely oxidized into β-Ga2O3 bulk film with nanometer island structure, and the crystal quality is significantly improved. The thermal oxidation process based on the GaAs single crystal proposed in this article can obtain nano-structured β-Ga2O3 bulk films of high crystal quality with high efficiency and low cost. This process enriches the application of β-Ga2O3 materials greatly.
关键词:thermal oxidation;nano island bulk film;β-Ga2O3;oxygen flow rate
摘要:A hybrid nanosystem of upconversion-bismuth integration(denoted as UBDAs) is designed and synthesized for near infrared(NIR) light-driven chemo-photothermal therapy. The obtained UBDAs present excellent photothermal conversion capacity (~28.5%) and good biocompatibility. Meanwhile, under excitation of NIR, UBDAs can emit ultraviolet/visible light, which promotes the continuous rotation-flip movement of the photosensitizer azobenzene in the mesoporous, thereby achieving the controlled drug release and avoiding the side effects of traditional ultraviolet light excitation on biological tissues. Photothermal experiments show that UBDAs hybrid nanosystems have a good photothermal effect under 980 nm laser irradiation. In addition, based on Tm3+ and Bi element the UBDAs are expected to be used in upconversion luminescence and X-ray computed tomography(CT) imaging to achieve dual-mode imaging-mediated and single NIR-driven chemotherapy and photothermal therapy. Therefore, this work provides a new idea for the integration of diagnosis and synergistically enhanced antitumor therapy.
摘要:Organic violet-blue luminescent materials have exhibited great potential in full-color displaying and lighting fields. However, it is a huge challenge to develop efficient violet-blue emitters because of the inherently wide energy gap. In this work, two violet-blue emitters with donor (D)-π-acceptor (A) type using 10H-phenothiazine 5,5-dioxide (2OPTZ) as a weak acceptor and N-(2-naphthyl) aniline (PNA) as the donor, namely 2OPTZ-PNA and 2OPTZ-BP-PNA, were designed and synthesized. By extending π-conjugation length between donor and acceptor, local excited states and charge transfer excited states were adjusted, and absolute photoluminescence quantum yields (PLQYs) values in the evaporated film increased from 14% to 33%. Notably, non-doped device based 2OPTZ-BP-PNA exhibits violet-blue light at 436 nm with a narrow full width at half-maximum (FWHM) of 54 nm, Commission Internationale de l’Eclairage (CIE) coordinates of (0.155, 0.046) and external quantum efficiency (EQE) of 4.1%. Given this, our results provide an efficient design strategy for the high-quality violet-blue luminescent materials.
摘要:940 nm vertical cavity surface emitting lasers(VCSELs) with different oxidation apertures were prepared. VCSELs with oxidation apertures of 3, 6,9 μm were tested and characterized. The maximum output power of VCSELs with oxidation aperture of 3, 6,9 μm is 2.92, 6.79,10.49 mW, respectively, and the modulation bandwidth of them is 27.65, 23.34, 20.56 GHz, respectively. In addition, VCSELs with an oxidation aperture of 3 μm can achieve single-mode operation under the whole working current, and VCSELs with an oxidation aperture of 6 μm and 9 μm show few mode and multi-mode characteristics under large current.Finally, VCSEL with oxidation apertures of 3 μm is selected for data transmission test, and the transmission rate of 53 Gbit/s under not return to zero(NRZ) is realized.
摘要:Planar structure photodetector based on a 2D/3D hybrid perovskite (PEA)0.15FA0.85SnI3/SnO2 heterojunction was constructed. It is found that the inserted SnO2 layer can manipulate the crystal growth process of the (PEA)0.15FA0.85SnI3 film, benefiting to form a dense and continued film. Under illumination of a 520 nm monochromatic light, the device shows a high response of 3.19×105 A/W, corresponding to a detectivity of 6.39×1015 Jones. While under illumination of an 808 nm monochromatic light, the device also shows a response of 1.70×104 A/W and a detectivity of 7.28×1013 Jones. These performances are dramatically higher than that device based on a simple (PEA)0.15FA0.85SnI3 film.On the one hand, the improvements are attributed to the improved morphology of the perovskite film, which increases the absorption efficiency and charge carrier collection efficiency of the device;on the other hand, the formation of a p-n junction between (PEA)0.15FA0.85SnI3 and SnO2 effectively increases the dissociation efficiency of the photogenerated electron-hole pairs in the perovskite and decreases the recombination probability of the electrons and holes. Moreover, the special electronic structure at the (PEA)0.15FA0.85SnI3/SnO2 interface may also trigger the device revealing a photoconduction gain.
摘要:The carrier concentration, spontaneous emission recombination rate and polarization field of dual-wavelength stacked c-plane InGaN/GaN multiple quantum wells(MQWs) light emitting diode(LED) are simulated with Crosslight APSYS software. The results show that the distribution of carriers, especially holes, in InGaN MQWs can be modified by adjusting the thickness of the well layer and barrier layer. Thus, the illumination in different spectral regimes can be balanced. Furthermore, the optical properties of semipolar InGaN/GaN LEDs with stacked MQWs grown under the same epitaxial conditions are analyzed. Finally, monolithic phosphor-free white LEDs with triple- wavelength stacked MQWs based on GaN micro arrays are proposed, in which the micro arrays consist of {1011} or {1122} semipolar facets and c faces. By adjusting the proportion of c-plane illumination, a white LED with color temperature of ~6 000 K and high color rendering index of ~91.3 can be achieved.
关键词:monolithic white LED;semipolarplane;InGaN;polarization effect
摘要:The low thermal conductivity of ordinary printed circuit board(PCB) material leads to poor heat dissipation performance, which makes it difficult to package high-power devices. In this work, a PCB substrate embedded with direct plated copper ceramic substrate(DPC)(hereinafter referred to as “embedded substrate”) is developed, which can enhance the local heat dissipation of PCB owing to the high thermal conductivity of ceramic materials, so it can be used for high-power LED packaging. Firstly, the DPC is fixed into the windowed PCB with adhesive, and the embedded substrate is obtained after electrical interconnection. Compared with ordinary PCB substrate, the surface temperature of embedded substrate is lower and the temperature rise trend is slow at the same current. When the current increases from 200 mA to 400 mA, the temperature rise of LED packaged with embedded substrate is about 42.1 ℃ lower than that of ordinary PCB substrate. At 350 mA, the thermal resistance and junction temperature of LED sample packaged with embedded substrate are 15.55 K/W and 9.36 ℃ respectively, and its optical power increases with the increase of current, which is always higher than that of LED packaged with ordinary PCB substrate under the same current. At 400 mA, the difference in optical power between them is about 16.7%. The experiments show that the embedded substrate is a high-performance and low-cost packaging substrate, which can effectively improve the heat dissipation performance of high-power LED and meet the packaging application requirements of power devices.
摘要:Carbon dots(CDs) generally refer to zero-dimensional carbon-based nanomaterials with a particle size of less than 20 nm and rich in functional groups such as hydroxyl, carboxyl and amino groups on their surface. Due to its excellent optical properties and easy functional modification, it has been widely used in biosensing, biological imaging, tumor therapy, antibacterial, and osteogenesis. It is expected to become the most promising carbon-based nanomaterials in the future. However, to truly push CDs to practical applications in biomedicine field, it must be functionalized. Surface passivation and heteroatomic doping are two common methods, and these two methods for functionalization of CDs were systematically summarized in this review. We hope to provide some methods and ideas for the functional design and their practical applications of CDs.