【作者】 郑新霞；

【导师】 张晓丹；

【作者基本信息】 南开大学 ， 信号与信息处理， 2011， 硕士

【摘要】 提高转换效率、降低成本是目前研究硅基薄膜太阳电池的两个关键问题。基于微晶硅电池的硅薄膜叠层电池可进一步拓宽硅薄膜电池的光谱吸收范围,提高其转换效率。单室沉积硅薄膜电池可大幅降低设备制造及维护成本。因此单室沉积硅基薄膜叠层太阳电池成为目前国际研究热点。本论文在比较成熟的非晶硅电池以及产业化单室制备的非晶硅/非晶硅叠层太阳电池基础上,开展基于单室沉积微晶硅电池的硅薄膜叠层太阳电池的研究工作。论文的主要内容与研究成果如下：一、研究了前氢等离子体处理对微晶硅薄膜初始生长阶段的影响,结合拉曼光谱和原子力显微镜的测试结果进行了相关的理论分析。通过对本征层材料的纵向结构及p/i界面的调控,实现了对单结微晶硅电池开路电压和短路电流的有效控制。1、针对微晶硅薄膜初始阶段生长对随后体材料的生长以及对p-i-n型电池p/i界面的影响,本论文提出采用前氢等离子体处理方法增加微晶硅薄膜生长初始阶段的成核密度,以使材料结构更为致密、改善纵向结构特性、降低非晶孵化层厚度。2、针对本征层材料纵向结构特性对微晶硅太阳电池性能的影响,本论文通过调节微晶硅电池中本征层材料沉积参数(硅烷浓度和辉光功率),实现对本征微晶硅薄膜纵向结构的调控。结果发现：电池性能主要取决于电池纵向结构的有效控制,开路电压和短路电流密度与p/i界面和本征层的初始生长有关。该结果对基于微晶硅基叠层电池的研究奠定了很好的基础。3、通过对电池本征层材料特性的优化、p/i界面污染的控制以及合理陷光结构的采用,在具有一定绒度的ZnO衬底上获得了光电转换效率达7.47%的单室沉积的单结微晶硅太阳电池。二、对基于单室沉积微晶硅太阳电池的非晶硅/微晶硅叠层太阳电池进行了研究。1、电流匹配是影响叠层电池转换效率的关键因素。本论文在固定顶电池厚度情况下,通过调节底电池的厚度,达到叠层电池电流的匹配。2、在电流基本匹配的情况下,通过调节底电池反应气体的硅烷浓度,进一步优化叠层电池性能。3、通过优化不同的微晶硅底电池本征层预氢等离子体辉光时间,控制电池p/i界面特性,使电池的开路电压和转换效率得到了提高。4、采用ZnO/Al复合背反射电极,1cm2单室沉积非晶硅/微晶硅叠层太阳电池的初始转换效率为11.04%；100cm2单室沉积非晶硅/微晶硅叠层电池组件的初始转换效率为9.53%。三、在单室中制备非晶硅/非晶硅/微晶硅三结叠层太阳电池。1、基于规模化生产的单室沉积的非晶硅/非晶硅叠层电池,本论文提出引入单室沉积的微晶硅电池,以进一步提高其转换效率。通过对生产线上单室制备的非晶硅/非晶硅叠层电池进行氢等离子体处理刻蚀非晶n,然后沉积微晶n,达到与底电池形成良好的隧穿结。2、通过优化n/p隧穿结以及微晶硅底电池的沉积条件,采用ZnO/Al复合背反射电极,制备出初始转换效率为9.52%单室沉积的非晶硅/非晶硅/微晶硅三结叠层太阳电池。将生产线上的单室沉积的非晶硅/非晶硅叠层电池效率,提高了两个多百分点。更多还原

【Abstract】 For silicon thin film solar cells, high photoelectric conversion efficiency of the solar cell and low cost are two key issues. Tandem solar cells based on microcrystalline silicon solar cells deposited in a single chamber can make much more use of solar spectrum and then has a great potential to increase the conversion efficiency. Plasma deposition of thin film silicon based solar cells in a single-chamber reactor leads to considerable simplifications and reduced costs as compared to multi-chamber processes. So, Tandem solar cells deposited in a single chamber system become a hot research topic of photovoltaic technology. In this thesis, based on the a-Si:H solar cells made by our laboratory or the a-Si:H/a-Si:H tandem solar cells realized in industry using completely single chamber deposition technique, Tandem solar cells based on microcrystalline silicon solar cells deposited in a single chamber were studied. The main research topics and results are described as follows.First of all, Combining Raman and AFM analyses, effect of pre-hydrogen glow discharge on initial growth of intrinsic microcrystalline silicon thin film were systematically investigated. The short circuit current density (Jsc) and open circuit voltage (Voc) were controlled though adjusting silicon concentration and deposition power.1. Considering the importance of initial growth of intrinsic microcrystalline silicon thin film for the subsequent bulk growth and p/i interface in p-i-n solar cells, in this thesis, pre-hydrogen glow method was used to improve nuclei density and reduce the thickness of amorphous incubation layer. The nuclei density obviously affects the subsequent bulk growth and also made the film more compact.2. Considering the significant relationship between the performance ofμc-Si:H solar cells andμc-Si:H thin film structure evolution along the growth direction, in this thesis, silicon concentration and deposition power were adjusted to controlμc-Si:H structure evolution along the growth direction. The result indicates that the performance ofμc-Si:H solar cells mainly depends on the well controlledμc-Si:H structure evolution along the growth direction, but the Jsc and Voc related with p/i interface and initial growth of intrinsic microcrystalline silicon thin film. The above result is very beneficial for modifying tandem solar cells based on microcrystalline silicon solar cells.3. Through the optimization of i layer and p/i interface inμc-Si:H solar cells and incorporation of light trapping,μc-Si:H solar cell with 7.47%(Area=1cm2) initial conversion efficiency was fabricated on a ZnO substrate with certain texture.Secondly, the performance of the micromorph tandem cells were improved by varyingμc-Si:H i-layer thinckness, silane concentration, and pre-hydrogen plasma time.1. Current matching of component cells is very important for tandem cells. In this thesis, fixed the thinckness of top cells at 250nm, current can be matched by adjusting the thinckness of bottom cell i-layer.2. Based on current matching of component cells, silane concentration for the i-layer of bottom cells was optimized for enhancing the performance of a-Si:H/μc-Si:H tandem solar cells.3. Pre-hydrogen plasma had an impact on the performance of p/i interface. Through optimizing pre-hydrogen plasma time, open circuit voltage and conversion efficiency of solar cells were improved.4. An initial conversion efficiency of 11.04% was achieved for micromorph tandem solar cell using ZnO/Al back reflector. Furthermore,100cm2 micromorph tandem module with 9.53% initial conversion efficiency was also obtained.Thirdly, a-Si:H/a-Si:H/μc-Si:H triple junction solar cell were fabricated in a single chamber system.1. Based on the a-Si:H/a-Si:H tandem solar cells realized in industry using single chamber deposition technique, H plasma glow was introduced to etch oxide on the surface, then aμc-Si:H n layer was deposited to obtain good n/p junction.2. a-Si:H/a-Si:H/μc-Si:H triple junction solar cells with 9.52% conversion efficiency have been successfully fabricated by changing deposition conditions for n/p tunnel junction andμc-Si:H bottom solar cells in a single chamber developed by our own. The photoelectric conversion efficiency of a-Si:H/a-Si:H tandem solar cells a-Si:H/a-Si:H/μc-Si:H triple junction solar cells show a increase of more then two percent improved efficiencies compared to a-Si:H/a-Si:H tandem solar cells realized in industry.更多还原