Optimization of broadband omnidirectional antireflection coatings for solar cells

Broadband and omnidirectional antireflection coating is generally an effective way to improve solar cell efficiency, because the destructive interference between the reflected and incident light can maximize the light transmission into the absorption layer. In this paper, we report the incident quantum efficiency ηin, not incident energy or power, as the evaluation function by the ant colony algorithm optimization method, which is a swarm-based optimization method. Also, SPCTRL2 is proposed to be incorporated for accurate optimization because the solar irradiance on a receiver plane is dependent on position, season, and time. Cities of Quito, Beijing and Moscow are selected for two-and three-layer antireflective coating optimization over λ = [300,1100] nm and θ = [0°, 90°]. The ηin increases by 0.26%, 1.37% and 4.24% for the above 3 cities, respectively, compared with that calculated by other rigorous optimization algorithms methods, which is further verified by the effect of position and time dependent solar spectrum on the antireflective coating design.

Development of Nanostructured Antireflection Coatings for EO/IR Sensor and Solar Cell Applications

Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor and photovoltaic module performance is the development of high quality nanostructure-based antireflection coatings. In this paper, we review our work on advanced antireflection structures that have been designed by using a genetic algorithm and fabricated by using oblique angle deposition. The antireflection coatings are designed for the wavelength range of 250 nm to 2500 nm and an incidence angle between 00 and 400. These nanostructured antireflection coatings are shown to enhance the optical transmission through transparent windows over a wide band of interest and minimize broadband reflection losses to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies.

Design of wideband graded-index antireflection coatings at oblique light incidence

We suggest a design method of graded-refractive-index （GRIN） antireflection （AR） coating for s-polarized or p- polarized light at off-normal incidence. The spectrum characteristic of the designed antireflection coating with a quintic effective refractive-index profile for a given state of polarization has been discussed. In addition, the genetic algorithm was used to optimize the refractive index profile of the GRIN antireflection for reducing the mean reflectance of s- and p-polarizations. The average reflectance loss was reduced to only 0.04% by applying optimized GRIN AR coatings onto BK7 glass over the wavelength range from 400 to 800 nm at the incident angle of θo = 70°.

Optimization of Multi-layer AR Coatings for GaInP/GaAs Tandem Solar Cells

The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.

Graded index broadband antireflection coating prepared by glancing angle deposition for a high-power laser system

This paper reports that SiO2 is selected to fabricate broadband antireflection （AR） coatings on fused silica substrate by using glancing angle deposition and physical vapour deposition. Through accurate control of the graded index of the SiO2 layer, transmittance of thc graded broadband AR coating can achieve an average value of 98% across a spectral range of 300-1850 nm. Moreover, a laser-induced damage threshold measurement of the fabricated AR coating is performed by using a one-on-one protocol according to ISOl1254-1, resulting in an average damage threshold of 17.2 J/cm2.

Preparation and Properties of TiN_x-SiO_2 Antireflective Coatings with Print Process

This paper describes the preparation and properties of TiN_x-SiO_2 double-layered antireflective(AR) coatings that were applied with print process. The coating material was analyzed and TiN_x was used instead of TiO_2 as high refractive material. The influence of solution concentration on AR property was studied. The testing result shows that the coatings using print process are featured with excellent mechanical property and the AR property is comparable to American Southwall AR product. It is expected that the study would promote the industrialization progress in AR coatings.

Lactiplantibacillus plantarum AR113 alleviates microbiota dysbiosis of tongue coating and cerebral ischemia/reperfusion injury in rat

Stroke is one of the leading causes of death and disability worldwide.However,information on stroke-related tongue coating microbiome(TCM)is limited,and whether TCM modulation could benefit for stroke prevention and rehabilitation is unknown.Here,TCM from stroke patients(SP)was characterized using molecular techniques.The occurrence of stroke resulted in TCM dysbiosis with significantly reduced species richness and diversity.The abundance of Prevotella,Leptotrichia,Actinomyces,Alloprevotella,Haemophilus,and TM7_[G-1]were greatly reduced,but common infection Streptococcus and Pseudomonas were remarkably increased.Furthermore,an antioxidative probiotic Lactiplantibacillus plantarum AR113 was used for TCM intervention in stroke rats with cerebral ischemia/reperfusion(I/R).AR113 partly restored I/R induced change of TCM and gut microbiota with significantly improved neurological deficit,relieved histopathologic change,increased activities of antioxidant enzymes,and decreased contents of oxidative stress biomarkers.Moreover,the gene expression of antioxidant-related proteins and apoptosis-related factors heme oxygenase-1(HO-1),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),nuclear factor erythroid 2-related factor 2(Nrf2),NAD(P)H:quinone oxidoreductase-1(NQO-1),and Bcl-2 was significantly increased,but cytochrome C,cleaved caspase-3,and Bax were markedly decreased in the brain by AR113 treatment.The results suggested that AR113 could ameliorate cerebral I/R injury through antioxidation and anti-apoptosis pathways,and AR113 intervention of TCM may have the application potential for stroke prevention and control.

在U表面循环Ar^+轰击-磁控溅射离子镀Al层

用循环Ar+ 轰击 -磁控溅射离子镀 (MSIP)法在U表面上镀Al,并采用俄歇电子能谱仪 (SAM )、扫描电镜(SEM)、电化学实验和湿热腐蚀加速实验 ,研究了其表面、剖面形貌和耐蚀性能 ,以及U基和Al镀层界面 .结果表明 :U上循环Ar+ 轰击 -磁控溅射离子镀Al界面存在较宽的原子共混区 。

U表面循环Ar^+轰击-磁控溅射离子镀Ti研究

用设计的循环Ar+轰击-磁控溅射离子镀法在U表面上镀Ti,并采用扫描电镜(SEM)、X射线光电子能谱仪和湿热加速腐蚀实验,研究了其表面、剖面形貌、镀层的组成与结构、膜基界面特征,以及耐湿热腐蚀性能。结果表明,U上循环Ar+轰击-磁控溅射离子镀Ti层结晶致密、晶粒细化,镀层由表及里分别由TiO2/TiO/Ti构成,镀层厚度≥4μm时、其试样的耐湿热腐蚀性能较之金属U来讲有较大程度的提高。

流动Ar和N_2对镀铬金刚石热处理后镀层组织的影响

研究了流动Ar和N2对镀铬金刚石热处理后镀层组织的影响,热处理温度分别为450℃、650℃和850℃,采用XRD、SEM和EDS方法对镀层组织进行了研究。研究结果表明,流动Ar时镀层易发生氧化,在较低的温度(如650℃)氧化已经十分显著,不同的是,流动N2氧化温度升高到850℃。在两种气氛下均发现,当热处理温度由650℃升至850℃时,镀层中碳化铬由低C/Cr相Cr7C3向高C/Cr相Cr3C2发生转化,且在氮气条件下转化率更高。上述现象归因于N2与镀层中的Cr反应生成了CrN,阻碍并延迟了镀层的氧化,有利于高温下金刚石表面的C原子与镀层中的Cr原子相互扩散。

利用半导体激光器功率—电流曲线斜率的变化控制AR膜的镀制

研究了不同偏置条件下半导体激光器的微分输出功率与端面反射率的关系,为主动法控制半导体光放大器端面减反射膜的镀制提供了必要的使用判据。镀膜实验证实了理论预测,使用本判据有助于提高镀膜的可靠性。

基于AR模型的Ni-SiC镀层磨损量预测研究

采用脉冲-电沉积方法在T8钢表面制备Ni-Si C镀层,利用扫描电镜(SEM)、XRD衍射仪和磨损试验机对Ni-Si C镀层的表面形貌、组分及其磨损性能进行分析,并利用AR模型对Ni-Si C镀层的磨损量进行预测。结果表明:当脉冲占空比为40%时,采用脉冲电沉积法制备Ni-Si C镀层的表面粗糙度较小、晶粒细小、组织较均匀;经XRD分析,证实Ni-Si C镀层中Si元素的存在;AR模型能够较好的对Ni-Si C镀层磨损量进行预测,预测结果相对误差的最大值仅为3.7%。

Ar/N_2气体比例对ZrN/WTiN纳米多层膜的影响

选择ZrN和WTi N作为个体层材料,利用超高真空射频磁控溅射系统制备ZrN,WTi N和一系列的ZrN/WTi N纳米多层薄膜.通过X射线衍射仪(XRD)和纳米力学测试系统分析制备参数中Ar/N2气体比例对多层膜结构与机械性能的影响.结果表明:多层膜的纳米硬度值普遍高于2种个体材料混合相的硬度值;当FAr∶FN2=5时,ZrN/WTi N纳米多层薄膜出现了ZrN(111),Ti N(111)衍射峰和非晶态,多层膜体系的硬度、应力和弹性模量均达到最佳效果.

基于AR模型的Ni-Al_2O_3复合镀层显微硬度预测

采用磁场电沉积方法在45钢表面制备了Ni-Al_2O_3复合镀层,用扫描电镜、显微硬度计等仪器对复合镀层表面及显微硬度进行检测。最后用AR模型对Ni-Al_2O_3复合镀层显微硬度进行预测。结果表明,当磁场强度0.3 T,Al_2O_3粒子浓度8 g/L,电流密度1.5 A/dm2时,Ni-Al_2O_3复合镀层表面较为平整,镀层缺陷较少。AR模型能够较好的预测Ni-Al_2O_3复合镀层显微硬度,最大相对误差仅为1.9%。

Modified-DBR-based semi-omnidirectional multilayer anti-reflection coating for tandem solar cells

In this paper, multilayer antireflection coatings are designed by modifying the thickness of two and three paired layer distributed Bragg reflector （DBR） structure. Our proposed DBR-based structures show antireflection behaviors, in spite of the reflection treatment in traditional DBR structures. Firstly, the proposed structures are designed to be equivalent to the theoretical ideal triple-layer （TL） antireflection coating （ARC）. Therefore, the problem of finding a suitable material for the middle layer of triple structure is solved. Simulation results show the significant equivalency for the reflectance of proposed structures to the ideal TL ARC at the same wavelengths and incident angles. Also, the design of the structure is changed in order to present the constant reflectance coefficient over a wide range of wavelengths. This structure enhances the omni-directionality of the multilayer ARC.

Optical, Mechanical and Laser-induced Damage Threshold Properties of 1064 nm, 532 nm Frequency-doubled Antireflection Coating for LBO

1 064 nm, 532 nm frequency-doubled antireflection （AR） coatings with buffer layer of SiO2 between the coating and the substrate were fabricated by the electron beam evaporation technology on the substrate of lithium triborate （LiB3O5 or LBO） crystals. The residual reflectance of the sample is 0.07% and 0.11% at 1 064 nm and 532 nm, respectively. The adhesion and the laser-induced damage threshold （LIDT） of the sample are greater than 200 mN and 18.6 J/cm2. The strengthening mechanism of adhesion and LIDT of the buffer layer of SiO2 were discussed by considering full plastic indentation and shear theory, and spallation of a plated film induced by thermal shock stress, respectively.

Employing SiO_2 Buffer Layer to Improve Adhesion of the Frequency-doubled Antireflection Coating on LBO

Frequency-doubled antireflection coatings simultaneously effective at 1064 nm and 532 nm were deposited on the lithium triborate （LiB3O5 or LBO） crystals using the electron beam evaporation method. Comparing with the sample without buffer layer, it is found that the adhesion of the sample with buffer layer of SiO2 between coating and LBO substrate is improved significantly from 137.4 mN to greater than 200 mN. And the laser-induced damage threshold is increased by 20% from 15.1 J/cm^2 to 18.6 J/cm^2. The strengthening mechanism of adhesion of the buffer layer of SiO2 is discussed by considering full plastic indentation and shear theory.

Accuracy design of ultra-low residual reflection coatings for laser optics

Refractive index inhomogeneity is one of the important characteristics of optical coating material, which is one of the key factors to produce loss to the ultra-low residual reflection coatings except using the refractive index inhomogeneity to obtain gradient-index coating. In the normal structure of antireflection coatings for center wavelength at 532 nm, the physical thicknesses of layer H and layer L are 22.18 nm and 118.86 nm, respectively. The residual reflectance caused by refractive index inhomogeneity（the degree of inhomogeneous is between -0.2 and 0.2） is about 200 ppm, and the minimum reflectivity wavelength is between 528.2 nm and 535.2 nm. A new numerical method adding the refractive index inhomogeneity to the spectra calculation was proposed to design the laser antireflection coatings, which can achieve the design of antireflection coatings with ppm residual reflection by adjusting physical thickness of the couple layers. When the degree of refractive index inhomogeneity of the layer H and layer L is-0.08 and 0.05 respectively, the residual reflectance increase from zero to 0.0769% at 532 nm. According to the above accuracy numerical method, if layer H physical thickness increases by 1.30 nm and layer L decrease by 4.50 nm, residual reflectance of thin film will achieve to 2.06 ppm. When the degree of refractive index inhomogeneity of the layer H and layer L is 0.08 and -0.05 respectively, the residual reflectance increase from zero to 0.0784% at 532 nm. The residual reflectance of designed thin film can be reduced to 0.8 ppm by decreasing the layer H of 1.55 nm while increasing the layer L of 4.94 nm.

退火Ar流速对VO_(2)薄膜热致变色光学性能的影响研究

本工作采用溶胶-凝胶法,以石英玻璃为衬底,乙酰丙酮氧钒(VO(acac)_(2))为钒源,高纯Ar为保护气体,在真空管式炉中以不同流速的Ar气氛下进行退火处理,制备出一系列具有不同热致变色性能的VO_(2)薄膜.采用XRD、FE-SEM、XPS、紫外-可见-近红外光谱仪表征薄膜的结构、表面形貌、V元素的价态、热致变色光学性能.结果表明:随着Ar流速的上升,VO_(2)薄膜的结晶质量持续下降,薄膜的近红外调节能力先上升后下降.当Ar流速为225 mL/min时,制备的VO_(2)薄膜综合性能最优:近红外调控效率(ΔT_(IR))达到20.2%,可见光透过率(T_(lum))为55.5%.

Silicon and III-V Solar Cells: From Modus Vivendi to Modus Operandi

In the present paper, some novel opportunities for the development of high-efficient Si and III-V-based solar cells are considered: energy-saving environment friendly low-temperature technology of forming p-n junctions in Si (1), elaboration of structurally perfect GaAs/Ge/Si epitaxial substrates (2) and application of protective antireflecting coatings based on cubic zirconia (3). As a result: 1) New technique of forming p-n junctions in silicon has been elaborated. The technique provided easy and comparatively cheap process of production of semiconductor devices such as solar cells. The essence of the technique under the study is comprised in formation p-n junctions in silicon by a change of conductivity in the bulk of the sample occurring as a result of redistribution of the impurities, which already exists in the sample before its processing by ions. It differs from the techniques of diffusion and ion doping where change of conductivity and formation of p-n junction in the sample occur as a result of introduction of atoms of the other dopants from the outside;2) The conditions for synthesis of GaAs/Ge/Si epitaxial substrates with a thin (200 nm) Ge buffer layer featured with (1 - 2) × 105 cm-2 density of the threading dislocation in the GaAs layer. Ge buffer was obtained by chemical vapor deposition with a hot wire and GaAs layer of 1 μm thick was grown by the metal organic chemical vapor deposition. Root mean square surface roughness of GaAs layers of the less than 1 nm and good photoluminescence properties along with their high uniformity were obtained;3) The conditions ensuring the synthesis of uniform functional (buffer, insulating and protective) fianite layers on Si and GaAs substrates by means of magnetron and electron-beam sputtering have been determined. Fianite films have been shown to be suitable for the use as an ideal anti-reflecting material with high protective and anticorrosive properties.