少子寿命值对太阳电池生产的监控作用

研究了太阳电池工艺过程中少子寿命值的变化,揭示了少子寿命值在太阳电池生产过程中的应用.通过比较工艺前后少子寿命值的变化,可以优化生产工艺,提高电池转换效率,改善电池的性能.经过工艺优化后,多晶硅太阳电池(非绒面)的平均转换效率达到14.75%.     

背面结构对铝背发射极n型单晶硅太阳电池的影响研究

研究背面结构对铝背发射极n型单晶硅太阳电池的影响,提出背面抛光结构铝背发射极n型单晶硅太阳电池的制备方法。使用少子寿命测试仪、扫描电镜(SEM)、量子效率测试仪及太阳电池测试仪对电池的表面复合速率、微观结构、量子效率和电性能进行测定。结果表明:对铝背发射极n型单晶硅太阳电池,背面抛光结构优于背面金字塔绒面结构,背面抛光结构可降低电池背面的复合速率、改善p-n结质量、提高量子效率,使电池转换效率提高0.34%。     

硅基薄膜太阳电池(九)

三单结硅基薄膜太阳电池的结构和工作原理1硅基薄膜太阳电池结构在常规的单晶和多晶太阳电池中,通常用p-n结结构。但对于硅基薄膜电池,所用的材料通常是非晶和微晶材料,由于非晶硅内存在大量尾态和悬挂键等缺陷态,载流子的迁移率很低,扩散系数也很低。如果采用通常的p-n结的电池结构,光生载流子在n型和p型中性掺杂区的扩散运动非常小,将直接影响短路电流。此外,由于非晶硅p-n结耗尽层内也存在着大量的缺陷态,会导致势垒区内光生载流子的大量复合。为此,硅基薄膜电池     

低成本绒面硅太阳电池新工艺

在硅太阳电池的制备过程中,将光刻技术与化学镀镍技术结合,一步形成硅太阳电池的正面栅电极与背面电极接触,可缩短生产周期,降低成本,为减少栅电极覆盖面积,提高电池的电性能提供条件。     

空间电荷区和晶界复合对多晶太阳电池基区少数载流子寿命的影响

该文采用多晶硅太阳电池模型，通过引入空间电荷区复合速度来研究空间电荷区复合对少子寿命的影响，从计算结果中发现当复合速率大于10^5cm／s时，空间电荷区的复合影响不可忽略，必须对所测得的寿命值进行修正。     

TDB－100硅太阳电池仿真及P－V特性研究

采用多项式数学模型对ＴＤＢ－１００硅太阳电池实测Ｉ－Ｖ数据进行拟合，可得到电池的实验模型，该模类具有很高的精度。运用这个模型对Ｐ－Ｖ特性进行分析，并根据电池的光照及温度特性，将该模型进行扩展，得到了电池的预计模型。     

TDB—100硅太阳电池仿真及P—V特性研究

采用多项式数学模型对ＴＤＢ－１００硅太阳电池实测Ｉ－Ｖ数据进行拟合，可得到电池的实验模型，该模类具有很高的精度。运用这个模型对Ｐ－Ｖ特性进行分析，并根据电池的光照及温度特性，将该模型进行扩展，得到了电池的预计模型。     

硅太阳电池的制作

太阳电池是一种光电转换器件,它能够直接把太阳能转变为电能,在空间和地面已有许多应用。今后在太阳能大规模应用方面,它将发挥越来越大的作用。太阳电池的种类很多,目前应用最多的是硅太阳电池,这种电池技术上比较成熟,性能稳定可靠,效率较高,能进行批量生产。下面简要介绍硅太阳电池的制作方法。 1.硅片的选择硅片是制作硅太阳电池的基本材料,它可以由纯度很高的硅单晶棒切割而成。选择硅片时要考虑硅材料的导电类型、电阻率、晶向、位错、寿命等。硅片通常加工成方形、长方形或圆形,厚度约0.35—0.40毫米。     

硅太阳电池稳步走向薄膜化

考察了硅太阳电池在光伏产业中所处的地位,分析了薄膜硅太阳电池的发展趋势。指出硅太阳电池在未来15a仍将保持优势地位,并继续沿着晶硅电池和薄膜硅电池两个方向发展。在此发展过程中,两个发展方向的主流很可能会汇合到一起,共同促使低成本、高效率、高可靠薄膜晶硅电池的诞生和产业化,从而继续保持硅太阳电池的优势地位。     

硅纳米线阵列太阳电池的性能分析

采用金属催化腐蚀法分别在(100)和(111)硅片表面制备出大面积垂直排列和倾斜排列的单晶硅纳米线阵列,垂直阵列在300～1000nm波段的平均反射率约为2.5%,倾斜阵列在该波段的平均反射率约为5%。基于垂直阵列和倾斜阵列制作的硅纳米线阵列太阳电池的最高转换效率分别为9.31%和11.37%。倾斜阵列电池的串联电阻比垂直阵列电池有所减小,使电池填充因子增大,性能有所提升。载流子复合是硅纳米线阵列太阳电池中电学损失的主导,使电池性能明显低于常规单晶硅电池。     

Cu5Si–Si/C composites for lithium-ion battery anodes

Cu₅Si–Si/C composites with precursor atomic ratio of Si:Cu = 1, 2 and 4.5 have been produced by high-energy ball-milling of a mixture of copper–silicon alloy and graphite powder for anode materials of lithium-ion battery. X-ray diffraction and scanning electron microscope measurements show that Cu₅Si alloy is formed after the intensive ball milling and alloy particles along with low-crystallite Si are interspersed in graphite uniformly. Cu₅Si–Si/C composite electrodes deliver a larger reversible capacity than commercialized graphite and better cyclability than silicon. The increase of copper amount in the composites decreases reversible capacity but improves cycling performance. Cu₅Si–Si/C composite with Si:Cu = 1 demonstrates an initial reversible capacity of 612 mAh g⁻¹ at 0.2 mA cm⁻² in the voltage range from 0.02 to 1.5 V. The capacity retention is respectively 74.5 and 70.0% at the 40th cycle at the current density of 0.2 and 1 mA cm⁻².     

Physical models for predicting the performance of Si/Si, AlGaAs/GaAs, and Si/SiGe solar cells

Analytical and physical models for homojunction and heterojunction solar cells are developed, and the performances of solar cells made by the Si/Si homojunction and made by the increasingly important and popular AlGaAs/GaAs and Si/SiGe heterojunctions compared. The models developed, which include relevant device physics such as the effective surface recombination velocity at the high-low junction and band discontinuities associated with heterojunctions, correctly explain the solar cell characteristics experimentally observed. Our calculations suggest that the highest efficiencies attainable for AlGaAs/GaAs, Si/Si, and Si/SiGe cells, with optimized doping concentrations but without surface passivation and geometry optimization, are 21.25%, 17.8% and 13.5%, respectively, under 1 AM1.5 sun condition. For concentrator cell applications, the efficiencies improve to about 24.5%, 22.2%, and 22.0% for AlGaAs/GaAs, Si/Si, and Si/SiGe cells, respectively, under 100 AM1.5 suns. While the AlGaAs/GaAs cell possesses the highest efficiency among the three cells, the Si/Si and Si/SiGe cells can achieve a satisfactory conversion efficiency at high sun concentration (22% at 100 suns), making them attractive for concentrator cell applications because their processing is the same as or is compatible with existing silicon technology. Model predictions for two Si/Si and one AlGaAs/GaAs cells compare favorably with data reported in the literature.     

Flexible Amorphous Si Solar Cells

Seasonal and temporal unbalanced demands of electric power are increasing year after year. While an even demand from the load must be maintained in order for the development of a typical solar power generation system for an ordinary usage in the near future, the most important aspect is to develop a low-cost system.

In this paper, the load pattern for a factory is chosen as the subject of the research, which has a lot of advantageous factors such as day-load and stability of the day to day load pattern. The two solar power generation systems which are shown below are investigated: one is connected with commercial power source and the other has equipment for charging the battery using low-cost night electric power. Both systems are simulated using meteorological data and are investigated not only from the energy flow in the systems but also from an economic viewpoint based on current constructive cost. In addition, the influence of the arrangement of holiday load patterns on the effective energy generated by photovoltaic panels are also researched.     

Lattice thermal conductivity of Si/Ge composite thermoelectric material: Effect of Si particle distribution

Embedding nanoparticles (NPs) in a matrix can effectively enhance the phonon scattering by the interface, reduce the lattice thermal conductivity, and improve the thermoelectric properties of the material. However, the understanding of how the distribution of embedded NPs affects the thermal conductivity is still not clear. To explore the underlying mechanism, frequency‐dependent Monte Carlo simulation and the effective medium method are applied to study the lattice thermal conductivity of Si/Ge composite (Si NPs embedded in Ge matrix). The effect of the free path distribution (FPD) of Ge phonon induced by the heterogeneous distribution of Si NPs is introduced into the effective medium method, and then, this method is used to calculate the lattice thermal conductivity of Si/Ge composite when Si NPs are unevenly distributed. Results show that decreasing the separation distance of adjacent NPs can slightly decrease the lattice thermal conductivity. Assuming that the FPD of Ge phonon induced by Si‐Ge interface scattering obeying lognormal distribution and that the deviation σ indicates the degree of inhomogeneity of Si NPs distribution, lattice thermal conductivity of composites with different σ is obtained. It is found that lattice thermal conductivity significantly decrease by more than 40%, with the increase of σ, especially for high‐Si concentrations. The present study indicates that the particle distribution in a composite can markedly affect the lattice thermal conductivity.     

The status of crystalline Si modules

The hope of a fast expansion of solar energy conversion by photovoltaics as a primary energy resource could be undeceived by the high production costs of PV modules The purpose of this work is firstly to discuss both technical and economical reasons yielding the present production cost levels of 4.5 $/Wp for standard crystalline silicon technology and secondly to indicate the development path necessary to achieve a cost of 2$/Wp, which is recognised as a threshold value for an effective use of PV     

Large area thin film Si module

An initial efficiency of 14.1% (J_sc=13.6 mA/cm², V_oc=1.392 V, FF=74.3%) has been achieved for a-Si/transparent interlayer/poly Si solar cell (total area of 1 cm²). Both a-Si and crystalline Si films were fabricated by plasma chemical deposition at low temperature. The short circuit current was enhanced by the introduction of a transparent intermediate layer. An initial aperture efficiency of 11.7% has been achieved for 910×455 mm² a-Si/poly Si integrated solar cell submodule, where the laser-scribing techniques were applied for series interconnections. The results of our first run of 266 submodules in our pilot plant showed the average efficiency of 11.2%, which is applicable for mass production.     

Evaluating influences of impurities on hydrogen production in the reaction of Si with water using Si sludge

Hydrogen has attracted much attention as a next-generation energy resource. Among various technologies, one of the promising approaches for hydrogen production is the use of the reaction between Si and water, which does not require any heat, electricity, and light energy as an input. Notwithstanding the usefulness of Si as a prospective raw material of hydrogen production, the manufacturing process of Si requires a significant amount of energy. Therefore, as an alternative to pure Si, this study used a wasted Si sludge, generated though the manufacturing process of Si wafer, for the direct reuse. Thus, the Si-water reaction for the hydrogen generation was investigated in comparison with pure Si and Si sludge by employing X-ray absorption near edge structure (XANES) to evaluate the feasibility of hydrogen production with the use of Si sludge and to identify the influence of impurities contained in Si sludge. As a result, hydrogen was not produced with the use of Si sludge because of containing Al compound as the impurity. Through the XANES analysis, the formation of SiO(OH)₂ was found as core-shell structure, which potentially would hinder the hydrogen generation.     

Optical confinement of the intermediate layer between Si and alumina substrate in thin film Si solar cells

Enhancement of the optical confinement effect by an intermediate layer (IML) between Si and alumina substrate in thin film Si solar cells was studied. The dependence of the optical confinement effect on refractive index of the IML and on thickness of Si was separately investigated by hemispherical reflectance measurement of the following two series of samples. In the first case, SiO_xN_y, SiN_x or TiO₂ was deposited as the IML in the multilayer, Si/IML/alumina. In the second case, Si layers with different thicknesses were formed. The study showed that in certain conditions the IML could enhance the optical absorption of Si layer in thin film Si solar cells.     

Investigation of Ag-bulk/glassy-phase/Si heterostructures of printed Ag contacts on crystalline Si solar cells

The interface structure of screen-printed silver contacts on a crystalline silicon solar cell has been studied by transmission electron microscopy (TEM). TEM results confirmed that the glassy-phase plays an important role in contact properties. There are at least three different microstructures present in optimal fired contacts. The location where silver-bulk directly contacts silicon is observed through SEM, and this is actually a very thin glass layer in between. In addition, high-density silver embryos on silicon were found for samples fired optimally. The results presented in this study suggest that Ag-bulk/thin-glass-layer/Si contact is the most decisive path for current transportation.     

Deposition and characterization of Al–Si metallic TBC precursor on Mo–Si–B turbine materials

The interfacial reactions of Mo–Si–B with Al–Si metallic coatings during processing to achieve high-temperature corrosion protective mullite coating for advanced turbine materials are discussed. Al–Si is being deposited on the Mo–Si–B substrate material by immersion in liquid Al–Si alloy, molten salt cathodic deposition, and organic electrolysis, to achieve adhesion and compositional gradients across the interfacial region. The interfacial region during Al–Si deposition is the precursor to the formation of compositionally graded mullite by annealing and subsequent oxidation. The optimum Al–Si content of this metallic layer, which will be attained by deposition combined with silicon diffusion from Mo–Si–B, is described. Characterization of the constitution and gradients across the interfacial region is reported. Transport modeling in this precursor layer and the substrate is discussed.