砷化镓基系Ⅲ-Ⅴ族化合物半导体太阳电池的发展和应用(1)

介绍以直接带隙Ⅲ-Ⅴ族材料为主体的多结叠层聚光太阳电池的特性和研发进展。据报道,三结叠层GaInP/GaAs/Ge太阳电池已成为空间能源的主力军,四结叠层GaInP/GaAs/GaInPAs/GaInAs聚光太阳电池的效率已达46.5%。在不远的将来,实现高效(50%)、低成本的Ⅲ-Ⅴ族多结叠层聚光电池是有现实可能的。     

三结太阳电池低频噪声特性与可靠性表征研究

以GaInP/InGaAs/Ge三结太阳电池为研究对象,通过宽范围电流偏置条件下的低频噪声测试和高温应力试验,对三结太阳电池的低频噪声特性和可靠性表征进行研究分析.结果表明,三结太阳电池的低频噪声包括1/f噪声和G-R噪声.在宽范围电流偏置条件下,低频噪声随偏置电流呈先增大后减小的规律,并在频率为500 Hz时出现G-...     

砷化镓基系Ⅲ-Ⅴ族化合物半导体太阳电池的发展和应用(7)

<正>2014年,天津三安光电公司报道,他们成功研发了晶格应变三结叠层GaInP/GaInAs/Ge高倍聚光电池,并进行了规模生产,聚光电池效率达到40%~41%。在青海神光格尔木建立了50 MW高倍聚光光伏电站,在青海日芯建立了60 MW高倍聚光光伏电站~([29])。3.3.3反向应变GaInP/GaAs/GaInAs三结叠层聚光电池改善GaInP/GaAs/Ge叠层电池能带匹配的     

QE测量在GaInP/GaAs叠层电池研究中的应用

该文介绍量子效率测量(QE测量)的原理以及此项技术在太阳电池研究中的应用.重点介绍QE测量在GaInP/GaAs叠层电池研究中的应用.给出了作者在美国Toledo大学进行的GaInP/GaAs叠层电池的QE测量的部分结果,并把这些结果与非晶硅(a-Si)三结叠层电池的QE测量结果进行了比较,对GaInP/GaAs叠层电池研究中的问题进行了分析,提出了改进的意见.     

用于高效级联太阳电池的ZnSe材料研究

研究了用于高效Znse／GaAs/Ge(硒化锌绅化镓／锗)级联太阳电池顶电池的ZnSe材料。用MBE技术制备了ZnSe p-n结样品，测量了其外量子效率；提出了改进ZnSe顶电池性能的方法；分析了ZnSe／GaAs／Ge结构比GaInP／GaAs／Ge结构的优越之处。     

多结太阳电池减反射膜的优化

基于多层膜的光学计算基本原理,模拟分析多结化合物太阳电池减反射膜的反射谱。模拟结果准确的反应了实际测量结果。以此为基础设计优化Ti O_x/Al_2O_3/MgF_2三层减反射膜,在GaInP/In_(0.01)GaAs/Ge三结太阳电池上实现了减反射膜对子电池响应电流的精确调节,并得到了子电池电流匹配的GaInP/In_(0.01)GaAs/Ge太阳电池,短路电流密度相比制备减反射膜前提升35.84%。     

用于GaInP/GaAs双结叠层太阳电池的MOVPE外延材料

采用金属有机化合物气相淀积(MOVPE)技术生长用于GaInP/GaAs双结叠层太阳电池的外延材料。针对材料生长中的隧穿结、p-AlInP层等关键问题,通过对掺杂剂、生长技术及条件的调整与改进,极大地提高了GaInP/GaAs双结叠层太阳电池性能,最高转换效率达到23.8%(AMO,25℃)。     

户外光谱下聚光多结太阳电池电流匹配的优化

针对户外变化的太阳光谱对多结太阳电池的电流匹配及效率有较大影响的问题,使用SMARTS软件计算青海格尔木地区全年不同时刻的户外太阳光谱,研究高倍聚光下Ga In P/Ga In As/Ge三结太阳电池在格尔木地区户外的输出特性;通过改变三结太阳电池各子电池的电流匹配,优化三结电池结构。结果表明:在不考虑聚光光学系统影响的情况下,中电池标准光谱响应电流比顶电池小5%的Ga In P/Ga In As/Ge三结太阳电池在格尔木地区全年输出的电量最大;而考虑特定光学系统的影响后,中电池标准光谱响应电流比顶电池小2.5%的Ga In P/Ga In As/Ge三结太阳电池在格尔木地区全年输出的电量最大。     

利用外量子效率研究太阳电池陷阱特性

利用SRH(Shockley-Read-Hall)复合理论,建立一种新的测量太阳电池材料中陷阱特性的模型。该模型描述了晶体硅太阳电池基区中的电子陷阱能级相对位置(E_t)、陷阱浓度(N_t)、陷阱对空穴与电子的俘获截面的比值(σ_p/σ_n)与晶体硅太阳电池的开路电压、外量子效率之间的关系。通过测量在有偏置光源和无偏置光源情况下,单晶硅和多晶硅太阳电池在500~1050 nm波长范围内单色光照射时的开路电压和外量子效率,计算出陷阱能级上电子浓度的变化量,从而获得电池基体材料中的陷阱特性。该方法可在室温下利用太阳电池量子效率测试系统进行测试,降低测量成本与测试复杂性,并且可扩展量子效率测试系统的应用。     

GaInP/GaAs/InGaAs倒装三结太阳电池设计与优化

为获得带隙组合对太阳光谱有效的分割利用,基于细致平衡原理,结合p-n结形成机理,应用Matlab语言对GaInP(1.90eV)/GaAs/InGaAs倒装结构电池体系底电池带隙和各子电池厚度进行模拟优化。结果表明底电池带隙为1.0eV时,光电转换效率最高。通过对GaInP(1.90eV)/GaAs(1.42eV)/InGaAs(1.0eV)倒装结构三结太阳电池各结厚度进行优化,综合考虑材料成本及生产技术等因素,最佳厚度组合为1.35、2.83和3.19μm时,光电转换效率为44.4%,仅比最高转换效率低0.3%。     

Optical properties and thermal stability of pulsed-sputter-deposited AlxOy/Al/AlxOy multilayer absorber coatings

Spectrally selective Al_xO_y/Al/Al_xO_y multilayer absorber coatings were deposited on copper (Cu) and molybdenum (Mo) substrates using a pulsed sputtering system. The Al targets were sputtered using asymmetric bipolar-pulsed DC generators in Ar+O₂ and Ar plasmas to deposit an Al_xO_y/Al/Al_xO_y coating. The compositions and thicknesses of the individual component layers were optimized to achieve high solar absorptance (α=0.950-0.970) and low thermal emittance (ε=0.05-0.08). The X-ray diffraction data in thin film mode showed an amorphous structure of the Al_xO_y/Al/Al_xO_y coating. The X-ray photoelectron spectroscopy data of the Al_xO_y/Al/Al_xO_y multilayer absorber indicated that the Al_xO_y layers present in the coating were non-stoichiometric. The optical constants (n and k) of the multilayer absorber were determined from the spectroscopic ellipsometric data. Drude's free-electron model was used for generating the theoretical dispersion of optical constants for Al films, while the Tauc-Lorentz model was used for modeling optical properties of the dielectric Al_xO_y layers. In order to study the thermal stability of the Al_xO_y/Al/Al_xO_y coatings, they were subjected to heat treatment (in air and vacuum) at different temperatures and durations. The multilayer absorber deposited on Cu substrates exhibited high solar selectivity (α/ε) of 0.901/0.06 even after heat-treatment in air up to 400 °C for 2 h. At 450 °C, the solar selectivity decreased significantly on Cu substrates (e.g., α/ε=0.790/0.07). The coatings deposited on Mo substrates were thermally stable up to 800 °C in vacuum with a solar selectivity of 0.934/0.05. The structural stability of the absorber coatings heat treated in air (up to 400 °C) and vacuum (up to 800 °C) was confirmed by micro-Raman spectroscopy measurements. Studies on the accelerated aging tests suggested that the absorber coatings on Cu were stable in air up to 75 h at 300 °C and the service lifetime of the multilayer absorber was predicted to be more than 25 years. Further, the activation energy for the degradation of the multilayer absorber heat treated for longer durations in air is of the order of 64 kJ/mol.     

Hydrogen storage properties of multi-principal-component CoFeMnTixVyZrz alloys

This study presents an innovative multi-principal-element CoFeMnTiVZr alloy system for the absorption and desorption of hydrogen. Pressure-composition-isotherms (PCIs) demonstrate that CoFeMnTi_xVZr, CoFeMnTiV_yZr, and CoFeMnTiVZr_z can absorb and desorb hydrogen for x, y, and z that satisfy 0.5 ≤ x ≤ 2.5, 0.4 ≤ y ≤ 3.0, and 0.4 ≤ z ≤ 3.0, respectively. X-ray diffraction (XRD) reveals that CoFeMnTi_xV_yZr_z alloys have a simple C14 Laves phase with a single set of lattice parameters before and after PCI tests. The distributions of each element in CoFeMnTi_xV_yZr_z alloys are roughly equal, as revealed by SEM/EDS mapping. The effects of values x, y, and z on the hydrogen storage properties are elucidated in terms of lattice constant, element segregation, hydride formation enthalpies of the alloy components and hydrogen, and the averaged formation enthalpy. The high-entropy effect promotes the formation of a single C14 Laves phase, and the maximum hydrogen storage capacity is strongly related to the hydride formation enthalpy of the alloy and hydrogen.     

C/H/O/N/S/Cl/K/Na元素的详细化学反应机理的简化与验证

基于Senkin模型,应用自编化学反应机理简化程序,结合Kinalc和Mechmod开源程序,发展了详细化学反应机理的简化与验证方法.以电站锅炉燃烧的计算流体力学(CFD)数值模拟为应用背景,建立了考虑C/H/O/N/S/Cl/K/Na元素的详细化学反应机理(115组分,1,342基元反应),并运用此方法得到简化反应机理(28组分,20反应).验证结果表明,该简化机理在锅炉运行的主要参数变化范围内(温度T=1,100～1,500,℃,过量空气系数λ=0.8～1.2)具有较好的准确性和较高的计算效率,可应用于锅炉燃烧的CFD计算.     

Electrochromic properties of NiOxHy thin films

NiO_xH_y films were prepared by DC magnetron sputtering in H₂/O₂ atmosphere. NiO_xH_y coatings with transparency and high electrochromic efficiency were obtained by changing H₂ content. A 60 nm thick NiO_xH_y film with transmittance of 0.57 (as-deposited state), 0.78 (bleached state) and 0.24 (coloured state) at wavelength of 550 nm was deposited in an atmosphere of H₂(60%)+O₂(40%). Analysis of infrared spectra (60002400 cm⁻¹) showed that the absorption peaks for bleached and colored states are associated with free ‘OH’ and OH stretching vibrations, respectively. XPS Ni2p core level spectra of colored NiO_xH_y film exhibited a peak at 856.2±0.2 eV which is attributed to Ni³⁺. Ni2p core level spectra of the bleached and as-deposited films exhibited two peaks at 856.4±0.2 and 854.6±0.2 eV which are attributed to Ni³⁺ and Ni²⁺.     

Optimization of buffer layers for lattice-mismatched epitaxy of GaxIn1−xAs/InAsyP1−y double-heterostructures on InP

We optimize InAs_yP_1−y buffer layers and compositional grades for lattice-mismatched heteroepitaxy of Ga_xIn_1−xAs/InAs_yP_1−y double-heterostructures on InP. The strains of the active and buffer layers depend on the bulk misfit difference between these layers. The misfit difference is adjusted to eliminate strain in the active layer, thus avoiding misfit dislocations and surface topography that would otherwise form to relieve strain. The optimized structure uses an “overshoot” with respect to the conventional design in the misfit and As composition of the InAs_yP_1−y buffer. Nearly optimized heterostructures typically show excellent structural quality and extended minority-carrier lifetimes.     

Explosion behavior of CH4/O2/N2/CO2 and H2/O2/N2/CO2 mixtures

In this work, the explosion behavior of stoichiometric CH₄/O₂/N₂/CO₂ and H₂/O₂/N₂/CO₂ mixtures has been studied both experimentally and theoretically at different CO₂ contents and oxygen air enrichment factors. Peak pressure, maximum rate of pressure rise and laminar burning velocity were measured from pressure time records of explosions occurring in a closed cylindrical vessel. The laminar burning velocity was also computed through CHEMKIN–PREMIX simulations.     

Structural and transport properties of LixNi1−y−zCoyMnzO2 cathode materials

In this work structural and transport properties of layered LiNi_1−y−zCo_yMn_zO₂ (y = 0.25, 0.35, 0.5 and z = 0.1) cathode materials are presented. In the considered group of oxides, LiNi_1−y−zCo_yMn_zO₂, there is no clear correlation between electrical conductivity and the a parameter (M-M distance in the octahedra layers). A non-monotonic modification of electrical properties of Li_xNi_0.65Co_0.25Mn_0.1O₂ cathode materials is observed upon lithium deintercalation.     

Characterization and voltammetric behavior of PtyMozOx/C electrodes prepared by the thermal decomposition of polymeric precursors

Carbon-supported catalysts containing platinum and molybdenum oxide are prepared by thermal decomposition of polymeric precursors. The Pt_yMo_zO_x/C materials are characterized by energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The catalysts present a well-controlled stoichiometry and nanometric particles. Molybdenum is present mainly as the MoO₃ orthorhombic structure, and no Pt alloys are detected. The voltammetric behavior of the electrodes is investigated; a correlation with literature results for PtMo/C catalysts prepared by other methods is established. The formation of soluble species and the aging effect are discussed.     

Experimental and modeling studies of C2H4/O2/Ar, C2H4/methylal/O2/Ar and C2H4/ethylal/O2/Ar rich flames and the effect of oxygenated additives

The addition of dimethoxymethane (DMM or methylal) and diethoxymethane (DEM or ethylal) to a rich ethylene/oxygen/argon flame has been investigated by measuring the depletion of soot precursors. Three rich premixed ethylene/oxygen/argon (with and without added methylal or ethylal) flat flames have been stabilized at low-pressure (50 mbar) on a Spalding–Botha type burner with the same equivalence ratio of 2.50. Identification and monitoring of signal intensity profiles of species within the flames have been carried out by using molecular beam mass spectrometry (M.B.M.S.). The replacement of some C₂H₄ by C₃H₈O₂ or C₅H₁₂O₂ is responsible for a decrease of the maximum mole fractions of the detected intermediate species. This phenomenon is noticeable for C₂–C₄ intermediates and becomes more effective for C₅–C₁₀ species, mainly when C₃H₈O₂ added.A new kinetic model has been elaborated and contains 546 reactions and 107 chemical species in order to simulate the three investigated flames: C₂H₄/O₂/Ar, C₂H₄/DMM/O₂/Ar and C₂H₄/DEM/O₂/Ar. The reaction mechanism well reproduces experimental mole fraction profiles of major and intermediate species, and underlines the effect of methylal and ethylal addition on species concentration profiles for these flames.     

Preparation and electrochemical properties of layer-structured LiNi1/3Co1/3Mn1/3−yAlyO2

Layer-structured LiNi_1/3Co_1/3Mn_1/3−yAl_yO₂ has been synthesized via a sol–gel method. The lattice constants of LiNi_1/3Co_1/3Mn_1/3−yAl_yO₂ decrease with the concentration of aluminum ions. XANES analysis further confirms that the valence of cobalt ion is 3+, and that of Ni is between 2+ and 3+ in LiNi_1/3Co_1/3Mn_1/3−yAl_yO₂. With doping aluminum ions, the redox centers for the electrochemical reaction change from nickel ions alone to both nickel and cobalt ions. The amounts of de-intercalatable lithium ions are affected by the concentration of aluminum ions; however, the extracting efficiency of lithium ions is improved by doping aluminum ions. Among all the samples, LiNi_1/3Co_1/3Mn_0.23Al_0.1O₂ exhibits the best capacity retention and the least irreversible capacity.