基于POLO钝化接触结构的晶硅电池技术及其研究进展

多晶硅氧化物(POLO)结构是在晶硅表面依次生长一层极薄的界面氧化层与多晶硅层所形成的钝化接触结构。基于POLO结构的钝化接触技术不仅能够获得优异的表面钝化特性,而且避免了金属与晶硅表面的直接接触,极大地降低了金属与晶硅表面的接触复合。目前应用POLO钝化接触结构制作的小面积晶硅太阳能电池转换效率高达26.1%,制作的大面积晶硅太阳能电池产业化效率已经超过24.5%。同时POLO钝化接触技术应用于晶硅电池的制作可以承受高温工艺,兼容现有的晶硅电池产业化设备,是未来极具产业化潜力的钝化接触技术方案。本文主要综述了POLO钝化接触结构中载流子的传输机理及相应的量化参数表征方法;对比了POLO结构制备中界面氧化层生长、多晶硅层的沉积、掺杂及氢化处理的方法;总结了多晶硅层的寄生吸收效应、晶硅表面形貌结构、掺杂浓度分布对POLO结构钝化接触特性的影响;简述了POLO钝化接触技术的研究进展及当前POLO电池制作面临的技术难点。

Crystalline Silicon Cells Technology Based on POLO Passivation Contact Structure and Its Research Progress

Poly-Si on oxide (POLO) structure is a passivation contact structure formed by growing a polysilicon layer on an extremely thin interface oxide layer based on the surface of the crystalline silicon. The passivation contact technology based on the POLO structure can not only obtain excellent surface passivation characteristics, but also avoid direct contact between the metal and the crystalline silicon surface, and greatly reduce the contact recombination of the metal and the crystalline silicon surface. At present, the conversion efficiency of small-area crystalline silicon solar cells made with POLO passivation contact structure is as high as 26.1%, and the industrialization efficiency of large-area crystalline silicon solar cells has exceeded 24.5%. At the same time, the POLO passivation contact technology applied to the production of crystalline silicon cells can withstand high-temperature processes and is compatible with existing crystalline silicon cell industrialization equipment. It is a passivation contact technology solution with great industrialization potential in the future. This paper mainly reviews the carrier transport mechanism in the POLO passivation contact structure and the corresponding quantitative parameter characterization methods. The methods of interfacial oxide layer growth, polysilicon layer deposition, doping and hydrogenation treatment in the preparation of POLO structure are compared. The parasitic absorption effect of the polysilicon layer, the morphological structure of the crystalline silicon surface, and the influence of the doping concentration distribution on the passivation contact characteristics of the POLO structure are summarized. The research progress of the POLO passivation contact technology and the difficulties in POLO solar cells production are briefly described.