快速汽相沉积法制备硅薄膜太阳电池

对在重掺杂抛光单晶硅衬底上用ＲＴＣＶＤ法形成硅薄膜太阳电池进行了研究。衬底为〈１００〉晶向ｐ＋ ＋ 型重掺硅片,电阻率为５×１０－ ３Ωｃｍ 。主要工艺过程为：在衬底上生长一层硅薄膜同时掺硼,膜厚３８μｍ ,扩磷制备ｐ－ｎ 结,背面蒸Ａｌ及Ｔｉ／Ｐｄ／Ａｇ 制背电极,正表面在扩散后生长一层ＳｉＯ２ ,前面用光刻剥离法制备Ｔｉ／Ｐｄ／Ａｇ 电极,制成的１ｃｍ ２ 太阳电池,开路电压ＶＯＣ＝ ６１２．８ｍ Ｖ,短路电流ＩＳＣ＝ ２９．３ｍ Ａ,填充因子ＦＦ＝ ０．７５７９,效率η＝ １３．６１。对一些影响电池特性的因素进行了研究,发现硅薄膜的掺杂浓度、发射层的掺杂浓度以及减反射层都对太阳电池的特性有较大影响。     

硅基太阳电池表面织构的研究进展

介绍了单晶硅、多晶硅和硅薄膜太阳电池绒面的不同制备方法,对这些方法所制备的绒面作了比较.最后展望了绒面技术对硅基太阳电池发展的推动作用.     

低纯度颗粒硅带上硅薄膜太阳电池

采用廉价国产硅粉拉制的低纯度颗粒硅带（SSP）作为衬底，利用快速热化学气相沉积（RTCVD）方法外延多晶硅薄膜并制作了转换效率达4．5％的薄膜太阳电池，对衬底和薄膜特性，相关工艺及进一步的研究方向做了探讨。     

颗粒硅带为衬底的多晶硅薄膜太阳电池制备工艺

主要阐述了以低纯度颗粒硅带(SSP—Silicon Sheet from Powder)为衬底的多晶硅薄膜(poly-CSiTF)太阳电池的制备，给出制得的太阳电池I—V曲线和光谱响应曲线并由此讨论影响电池性能的可能因素，着重分析了颗粒硅带衬底的作用。目前，在没有任何电池工艺优化的条件下，在低纯度硅带上制得多晶硅薄膜电池的转换效率通常在5％～7％范围(电池面积1cm^2)。     

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。     

硅基薄膜太阳电池（十）

单结硅基薄膜太阳电池的Ｖoc、Jsc。与带隙之间的实验结果如图48所示。由图中可知,晶体材料基本符合Green的半经验极限,据Kiess的理论数值有一个近乎平行的整体位移,而薄膜电池中多晶CdTe电池离Green极限有一定差距,而无定形非晶硅电池则差距较大,这与薄膜材料的结构、性能、制备工艺成熟程度明显相关。该数据对非晶硅电池的数据显得陈旧,目前Koc达到1V并非难事。     

高效单晶硅太阳电池的研制

简述了高效单晶硅太阳电池的初步研制结果。对电阻率不同的ＣＺ和ＦＺ材料和不同的电池结构进行了实验。为了提高效率，对发射区钝化工艺、分区轻（ｎ＾＋）重（ｎ＾＋＋）扩散、背场、表面织构化技术和氯清洗等工艺进行试验研究。目前制备的最好电池，其效率为１８．６３％。     

晶体硅薄膜太阳电池的衬底材料--颗粒硅带(SSP)的制备

晶体硅薄膜太阳电池（CSiTF-Crystalline Silicon Thin Film Solar Cells)由于具有降低制造成本的空间， 成为目前研究工作的一 个热点。我们将注意力集中在低成本、可连续化的硅衬底制备上，即颗粒硅带（SSP-Silicon Sheet from Powder)制备技术。可以使用不同纯度、粒度的硅粉，经过光聚焦加热熔化，最后得到不同长度、宽度和厚度的颗粒硅带衬底材料。介绍了晶体硅薄膜太阳电池衬底材料的现状，并描述实验室的颗粒硅带制备技术。     

多晶硅薄膜太阳电池衬底选择的研究进展

多晶硅薄膜太阳电池因其转换效率高、寿命长和工艺简化等优点而极具潜力。衬底的选择和制备工艺的研究是目前多晶硅薄膜太阳电池的研究重点。本文对多晶硅薄膜太阳电池衬底选择的研究进展作了介绍。     

非晶硅太阳电池的原理

非晶硅太阳电池是２０世纪７０年代中期发展起来的一种新型薄膜太阳电池，与其他太阳电池相比，非晶硅电池具有以下突出特点：（１）制作工艺简单，在制备非晶硅薄膜的同时就能制作pin结构。（２）可连续、大面积、自动化批量生产。（３）非晶硅太阳电池的衬底材料可以是玻璃、不锈钢等，因而成本小。（４）可以设计成各种形式，利用集成型结构，可获得更高的输出电压和光电转换效率。（５）薄膜材料是用硅烷（SiH４）等的辉光放电分解得到的，原材料价格低。１非晶硅太阳电池的结构、原理及制备方法非晶硅太阳电池是以玻璃、不锈钢及特种…     

Amorphous silicon solar cells

The perfectioning of the deposition techniques of amorphous silicon over large areas, in particular film homogeneity and the reproducibility of the electro-optical characteristics, has allowed a more accurate study of the most intriguing bane of this material: the degradation under sun-light illumination. Optical band-gap and film thickness engineering have enabled device efficiency to stabilize with only a 10–15% loss in the as-deposited device efficiency. More sophisticated computer simulations of the device have also strongly contributed to achieve the highest stable efficiencies in the case of multijunction devices. Novel use of nanocrystalline thin films offers new possibilities of high efficiency and stability. Short term goals of great economical impact can be achieved by the amorphous silicon/crystalline silicon heterojunction. A review is made of the most innovative achievements in amorphous silicon solar cell design and material engineering.     

Modelling of material properties influence on back junction thin polycrystalline silicon solar cells

The influence of polycrystalline silicon properties on the performances of thin back junction solar cells has been investigated by means of a 3-dimensional model taking into account grain size, grain boundary recombination, volumic recombination, and surface recombination. The drastic influence of front surface recombination has been confirmed. The grain size has been shown to be of minor importance provided the grain size is not too small and the grain boundaries are correctly passivated. An optimal base thickness has been determined which is all the smaller that the material is more imperfect.     

The influence of porous silicon on junction formation in silicon solar cells

In this work the results of a structural investigation by SEM of porous silicon (PS) before and after diffusion processes are reported. The formation of PS n⁺/p structures were carried out on PS p/p silicon wafers with two methods: from POCl₃ in a conventional furnace and from a phosphorous doped paste in an infrared furnace. Sheet resistance was found to be a strong function of PS structure. Further details on sheet resistance distribution are reported. The electrical contacts in prepared solar cells were obtained by screen printing process, with a Du Ponte photovoltaic silver paste for front contacts and home-prepared silver with 3% aluminium paste for the back ones. Metallization was done in the infrared furnace. Solar cell current–voltage characteristics were measured under an AM 1.5 global spectrum sun simulator. The average results for multi-crystalline silicon solar cells without antireflection coating are: I_sc=720 (mA), V_oc=560 (mV), FF=69%, Eff=10.6% (area 25 cm²).     

Substrates for thin crystalline silicon solar cells

Choice of substrate for thin crystalline silicon solar cells requires a compromise between cost and quality. There are three generic substrate types, namely a transparent substrate (such as glass), an opaque substrate (such as a ceramic or metal) and low-cost multicrystalline silicon. Glass has the advantage of eliminating absorption within the substrate. However, the larger effective diffusion length, the improved surface passivation and the increased process flexibility obtainable with an opaque substrate, particularly low-cost multicrystalline silicon, may considerably outweigh the modest optical benefits of a transparent substrate. In this paper it is shown that the advantage in effective diffusion length that is required of a cell grown on an opaque substrate in order to offset the light-trapping advantages of a glass substrate is about a factor of two.     

Rie-texturing of multicrystalline silicon solar cells

We developed a maskless plasma texturing technique for multicrystalline silicon cells using reactive ion etching that results in higher cell performance than that of standard untextured cells. Elimination of plasma damage has been achieved while keeping front reflectance to extremely low levels. Internal quantum efficiencies as high as those on planar cells have been obtained, boosting cell currents and efficiencies by up to 7% on evaporated metal and 4% on screen-printed cells.     

High-efficiency multicrystalline silicon solar cells by liquid phase-epitaxy

Thin-film silicon cells produced on crystalline silicon substrates have the potential to achieve high cell efficiencies at low cost. We have used a modified liquid-phase epitaxy growth process to produce very smooth, high-quality silicon films on multicrystalline silicon substrates. Photoconductivity decay measurements indicate that the minority carrier lifetimes in these layers are at least 10 μs, sufficient to achieve cell efficiencies in excess of 16%. This efficiency potential is confirmed in small area cells, which have displayed efficiencies up to 15.4%. Further improvements up to 17% efficiency are possible in the short term, even without the introduction of any light-trapping schemes into the device structure.     

Milestones in the development of crystalline silicon solar cells

The development of crystalline silicon solar cells is traced from their invention to the present day, with an emphasis on the major advances (“milestones”) along the way. The survey covers cells for power generation in space as well as those for terrestrial applications.     

Applying analytical and numerical methods for the analysis of microcrystalline silicon solar cells

The results of numerical device simulations for p–i–n diodes and the closed-form expression of the current–voltage characteristics developed for p–n diodes are compared. It is shown that the closed-form expression correctly predicts the functional relationship between material parameters and device performance of p–i–n diodes. The ideality factor between 1 and 2 is analyzed in detail. The effect of the defect density, the intrinsic carrier concentration, the mobility and the built-in potential on device performance are demonstrated. These insights are applied to analyze microcrystalline silicon thin-film solar cells deposited by chemical vapor deposition at temperatures below 250 °C.     

The influence of drift fields in thin silicon solar cells

The influence of electric “drift” fields in the base of silicon solar cells on device performance is investigated. The drift fields are the result of a nonuniform dopant density in the base material. Numerical modelling is carried out for a range of representative cell structures and two different models for the dependence of the minority carrier lifetime on the dopant density. The cell design variables, in particular the dopant densities and the thicknesses of the device regions, are optimized with respect to the cell efficiency. Comparison of optimized cells incorporating a drift field with those not having a drift field, shows that a drift field can offer only small efficiency advantages for particular cell structures and recombination parameters, and only if large variations in dopant concentration can be achieved.     

Realization of high efficiency micromorph tandem silicon solar cells on glass and plastic substrates: Issues and potential

High conversion efficiency for (amorphous/microcrystalline) "micromorph" tandem solar cells requires both a dedicated light management, to keep the absorber layers as thin as possible, and optimized growth conditions of the microcrystalline silicon (μc-Si:H) material. Efficient light trapping is achieved here by use of textured front and back contacts as well as by implementing an intermediate reflecting layer (IRL) between the individual cells of the tandem. This paper discusses the latest developments of IRLs at IMT Neuchâtel: SiO_x based for micromorphs on glass and ZnO based IRLs for micromorphs on flexible substrates were successfully incorporated in micromorph tandem cells leading to high, matched, current above 13.8 mA/cm² for p-i-n tandems. In n-i-p configuration, asymmetric intermediate reflectors were employed to achieve currents of up to 12.5 mA/cm². On glass substrates, initial and stabilized efficiencies exceeding 13% and 11%, respectively, were thus obtained on 1 cm² cells, while on plastic foils with imprinted gratings, 11.2% initial and 9.8% stable efficiency could be reached. Recent progress on the development of effective front and back contacts will be described as well.