Redox MXene Artificial Synapse with Bidirectional Plasticity and Hypersensitive Responsibility

Artificial synapses are key elements for the nervous system which is an emulation of sensory and motor neuron signal transmission. Here, the design and fabrication of redox-behavior the metal carbide nanosheets, termed MXene artificial synapse, which uses a highly-conductive MXene electrode, are reported. Benefiting from the special working mechanism of ion migration with adsorption and insertion, the device achieves world-record power consumption (460 fW) of two-terminal synaptic devices, and so far, the bidirectionally functioned synaptic device could effectively respond to ultra-small stimuli at an amplitude of ±80 mV, even exceeding that of a biological synapse. Potential applications have also been demonstrated, such as dendritic integration and memory enhancement. The special strategy and superior electrical characteristics of the bidirectionally functioned electronic device pave the way to high-power-efficiency brain-inspired electronics and artificial peripheral systems.     

大屏幕投影拼接系统的设计

设计了一个可实现无缝拼接系统的研究示例:将一个高分辨率的图像分为两个分图像,按两部分在边缘交叠的方式分别投影。在投影之前,选用简单的线性函数关系,对待重叠部分进行了淡入淡出的处理,经这样叠加后重叠部分的重叠痕迹可适当消除。但鉴于像素信号与亮度之间还应满足伽马(Gamma)关系,故在处理过程中同时进行了Gamma校正的设计。研究过程中,考虑到不同成像终端之间,在色度表征方式以及Gamma校正已有自身规则,可方便转换,文章从简化研究出发,首次采用当前计算机监视器的液晶屏为投影成像的终端,研究它的融合结果,并实测融合图像部分的光强,以检查融合的实际效果。发现采用简单的线性函数并选择2.15的Gamma校正值,较之未作伽马校正前的,能改善融合区与未处理区的亮度差异达两个量级。最后给出了经这样处理后在液晶显示屏上获得较为良好的拼接效果。     

Electronic and optoelectronic properties of zinc phthalocyanine single-crystal nanobelt transistors

ZnPc single-crystal nanobelts were grown by a physical vapor transport process with the length ranging from 20 to 150 μm and the width ranging from several tens of nanometers to several micrometers. Based on high crystalline ZnPc nanobelts, its single-crystal nanobelt transistors were realized. The field-effect mobility is as high as 0.75 cm²V⁻¹s⁻¹ with OTS modified SiO₂ as dielectric, which is the highest value for the reported ZnPc devices. In addition, ZnPc nanobelt transistors show the excellently photosensitive properties with the high photoswitching ratio (|I_light/I_dark|) of 7.34 × 10³ and the high photoresponsivity at 1.57 × 10⁴ AW⁻¹. These results indicate the future potential of ZnPc single-crystal transistors in organic electronic and optoelectronic applications.     

Optoelectronic characteristics of MEH-PPV polymer LEDs with thin,doped composition-graded a-SiC:H carrier injection layers

The optoelectronic characteristics of poly(2-methoxy-5-(2′ethyl-hexoxy)-1,4-phenylene-vinylene) (MEH-PPV) polymer LEDs (PLEDs) have been improved by employing thin doped composition-graded (CG) hydrogenated amorphous silicon–carbide (a-SiC:H) films as carrier injection layers and O₂-plasma treatment on indium–tin-oxide (ITO) transparent electrode, as compared with previously reported ones having doped constant-optical-gap a-SiC:H carrier injection layers. For PLEDs with an n-type a-SiC:H electron injection layer (EIL) only, the electroluminescence (EL) threshold voltage and brightness were improved from 7.3 V, 3162 cd/m² to 6.3 V, 5829 cd/m² (at a current density J = 0.6 A/cm²), respectively, by using the CG technique. The enhancement of EL performance of the CG technique was due to the increased electron injection efficiency resulting from a smoother barrier and reduced recombination of charge carriers at the EIL and MEH-PPV interface. Also, surface modification of the ITO transparent electrode by O₂-plasma treatment was used to further improve the EL threshold voltage and brightness of this PLED to 5.1 V, 6250 cd/m² (at J = 0.6 A/cm²). Furthermore, by employing the CG n[p]-a-SiC:H film as EIL [hole injection layer (HIL)] and O₂-plasma treatment on the ITO electrode, the brightness of PLEDs could be enhanced to 9350 cd/m² (at a J = 0.3 A/cm²), as compared with the 6450 cd/m² obtained from a previously reported PLED with a constant-optical-gap n-a-SiCGe:H EIL and p-a-Si:H HIL.     

LCoS背投技术及其在中国的发展

作为新兴的显示技术,LCoS一直被认为是未来最具竞争力的技术。与LCD和DLP两种背投技术相比,LCoS技术具有结构简单、成本更低的优势,并且具有高解析度、高亮度的特性。LCoS光学引擎是整个背投的一个重要组成部分。三片式LCoS光学引擎是目前市场上LCoS高清背投电视采取的主要光学引擎架构。     

Luminescence properties of Ca2GdNbO6: Sm3+, Eu3+ red phosphors with high quantum yield and excellent thermal stability for WLEDs

A series of Ca₂GdNbO₆: xSm³⁺ (0.01 ≤ x ≤ 0.15) and Ca₂GdNbO₆: 0.03Sm³⁺, yEu³⁺ (0.05 ≤ y ≤ 0.3) phosphors were synthesized by the traditional solid-state sintering process. XRD and the corresponding refinement results indicate that both Sm³⁺ and Eu³⁺ ions are doped successfully into the lattice of Ca₂GdNbO₆. The micro-morphology shows that the elements of Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphor are evenly distributed in the sample, and the particle size is about 2 μm. The optical properties and fluorescence lifetime of Ca₂GdNbO₆: 0.03Sm³⁺, Eu³⁺ phosphors were detailedly studied. The emission peak at ⁵D₀→⁷F₂ (614 nm) is the strongest and emits red light under 406 nm excitation. The increase of Eu³⁺ concentration causes the energy transfers from Sm³⁺ to Eu³⁺ ions, and the transfer efficiency reaches 28.6%. Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphor has a quantum yield of about 82.7%, and thermal quenching activation energy is of 0.312 eV. The color coordinate (0.646, 0.352) of Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphors is located in the red area. The LED device fabricated based on the above phosphor emit bright white light, and CCT = 5400 K, Ra = 92.8. The results present that Ca₂GdNbO₆: 0.03Sm³⁺, Eu³⁺ phosphors potentially find use in the future.     

A single‐phase,thermally stable and color-tunable white light emitting Na2Ca1-x-yCexMnyP2O7 phosphors for white light emitting diodes via energy transfer

The solid-state reaction method was used to develop a series of Na₂Ca_1-x-yCe_xMn_yP₂O₇ phosphors in an H₂–N₂ environment. The crystal structure of the pyrophosphate host, valence state of dopants (Ce, Mn), emission behavior of dopants, energy transfer mechanism, and thermal quenching behavior were thoroughly examined. Doping with Ce³⁺ and Mn²⁺ ions enhanced the photoluminescence characteristics of Na₂Ca_1-x-yCe_xMn_yP₂O₇ while having negligible effect on the host's phase purity. Under 365 nm UV light irradiation, the addition of Ce³⁺ ion in the Na₂CaP₂O₇ host revealed an asymmetric band with the typical blue emission around 415 nm and a shoulder around 455 nm. To obtain white light, Mn²⁺ ion was supplementarily substituted to the present system. When the Mn²⁺ ions concentration was elevated in the Na₂CaP₂O₇ host, the emission intensity of 560 nm peak corresponding to Mn²⁺ transition enhanced significantly at the cost of Ce³⁺ emission of 415 nm. The systematic decrease of Ce³⁺ emission intensity and corresponding increase in the Mn²⁺ intensity with the increase in Mn²⁺ concentration indicated the possibility of effective energy transfer from Ce³⁺ to Mn²⁺ ions. The obtained results indicated that energy transfer from the Ce³⁺ to Mn²⁺ ions governed by dipole-quadrupole interaction. Because of the efficient energy transfer, the blue emission from Ce³⁺ and the orange red emission of Mn²⁺ provide white light from a single host along with high value of activation energy and low thermal quenching behaviour make the present phosphors to be suitable for high-power LEDs.     

Fabrication and characterization of a tiny PZT thick-film longitudinal-bending coupled drive vibrator using electrohydrodynamic jet printing

This paper describes a fabrication method of a novel type of micro piezoelectric thick-film longitudinal-bending coupled (LBC) vibrator with a length of 8 mm and thickness of 0.34 mm using electrohydrodynamic jet (E-jet) printing. The LBC micro-vibrator was designed, and a frequency sensitivity analysis of the structural parameters was implemented. When the thickness of the lead zirconate titanate (PZT) thick-film element of the vibrator reached 76 μm, tuning of the composite-mode frequency consistency could be achieved. The micro-vibrator was then fabricated by depositing the PZT thick film directly on the surface of the elastic body using E-jet printing, and the film thickness was flexibly adjusted by tuning the number of prints, thus avoiding the problems of insufficient PZT thin film thickness (≤1 μm) and excessive bulk PZT ceramic volume. Micro-morphological observations showed that the printed thick film was dense and smooth, with a thickness of approximately 76 μm. Furthermore, the vibration mode frequency of the vibrator differed from the test resonant frequencies by only 0.92%, and the vibrator could achieve driving motion with a volume and an excitation voltage approximately one-tenth of that of a bulk piezoelectric motor. Moreover, the unit power density was 0.36 W kg⁻¹ V⁻¹, which is 1.6 times higher than that of a large bulk piezoelectric motor, indicating that the vibrator has good potential for small-space and low-voltage applications.     

IWO缓冲层对MOCVD-ZnO:B薄膜性能的影响研究

金属有机化学气相沉积(MOCVD)技术生长的绒面ZnO透明导电(ZnO-TCO)薄膜应用于Si基薄膜太阳电池上能够形成"陷光结构",以提高薄膜太阳电池效率和稳定性。本文将电子束反应蒸发技术生长的掺W的In2O3(In2O3:W,(IWO)薄膜作为缓冲层,应用于MOCVD-ZnO:B薄膜与玻璃之间,可促进ZnO:B薄膜的生长,并且有效提升薄膜的光散射特性。当IWO缓冲层厚度为20nm时,获得的IWO/ZnO:B薄膜的电阻率为2.07×10-3Ω.cm,迁移率为20.9cm2.V-1.s-1,载流子浓度为1.44×1020 cm-3;同时,薄膜具有的透过率大于85%,且在550nm处绒度较ZnO:B薄膜提高了约9.5%,在800nm处绒度较ZnO:B薄膜提高了约4.5%。