背钝化接触晶硅电池的发射极和绒面结构优化及光电性能调控研究

In order to promote the cost reduction and efficiency improvement of crystalline silicon solar cells and realize the ‘grid parity’ of photovoltaics at an early date, in this project, the authors intend to further improve the efficiency of tunnel oxide passivated contact solar cells by optimizing the emitter performance and the light trapping ability. The authors innovatively propose to improve the uniformity of the emitter by new inverted pyramid texture, laser doped selective emitter and alumina/silicon nitride double passivation layer, leading to optimization of the optical and electrical performances of the emitter. Meanwhile, appropriate texture is introduced on the backside of the solar cell with SiO2/n+ poly Si passivated contact, which increases the photo-generated current without reducing the surface passivation performance. While optimizing the silicon solar cell technology to achieve higher conversion efficiency, this project will also systematically and deeply analyze some key scientific problems in crystalline silicon cells, for example, the precise control of inverted pyramid texture, the doping behavior of impurities in different texture, the influence of the front and back texture on light absorption, surface passivation, and carrier transport. Finally, the deep understanding of the key issue in silicon solar cells, which is the conversion between light and electricity, will lead to better design for higher efficiency silicon solar cells.

为了推进晶硅电池的降本增效、早日实现光伏“平价上网”，本项目拟通过优化发射极性能和陷光能力两方面进一步提升具量产可能性的隧道氧化层钝化接触电池的效率。创造性地提出通过匹配新型倒金字塔绒面改善发射极的均匀性，并结合激光掺杂选择性发射极技术和Al2O3/SiNx双层钝化技术，将电池发射极的光电性能提升到最佳值。同时，在电池背面引入适当的绒面结构，结合SiO2/n+ polySi钝化接触技术，使其增加光生电流的同时不降低表面钝化性能。在优化电池技术、获得更高转换效率的同时，本项目拟对晶硅电池中的一些关键科学问题进行系统深入的分析。例如，倒金字塔绒面的精确调控，杂质在不同绒面的掺杂行为，以及正反面绒面结构对光吸收、表面钝化、载流子输运的影响等。通过对晶硅电池中光电转化这一核心问题的深入理解，为后续更高效晶硅电池的设计研发提供方向。

本项目从提高太阳能电池发射极和背面的光电性能出发，系统研究了基于倒金字塔绒面结构的TOPCon电池的光电性能，主要进展如下：（1）通过系统研究铜催化刻蚀条件和后刻蚀条件，成功实现了倒金字塔绒面的批量可控制备。（2）针对倒金字塔绒面设计了Al2O3/SiNx双层钝化减反射膜，并根据光电性能对工艺参数进行了优化。（3）系统研究了多种背面绒面结构、开发了相应的添加剂，发现碱抛光获得的光滑平面具有最优异的电池性能。（4）获得了大面积（158.75×158.75 mm2）转化效率为22.84%的倒金字塔绒面TOPCon电池。