多晶硅太阳电池表面激光电化学复合阵列织构机理研究

The utilization of solar energy has become a hot-spot of research on new energy. In order to solve the problem of low photoelectric conversion efficiency for multicrystalline silicon solar cells in photovoltaic industry, a new hybrid texturing method combined of laser etching and electrochemical machining has been developed based on the research of the array texturing mechanism. The new process can overcome the defects of traditional method such as disordered distribution and low repeatability. It can effectively reduce the reflectivity of multicrystalline silicon solar cells with high quality texturing of precision controlled and ordered light traps. The mechanism of the hybrid texturing method was revealed by the research on three scientific issues. The issues include the forming law of minimally machining on the surface of multicrystalline silicon with laser machining in liquid environment, the influencing law of the free-carrier generated from the laser-induced multicrystalline silicon on anodic dissolution, and the enhancement effect of ECM actions by the rapid dissolution for passive oxide films with laser irradiation. On the basis of above-mentioned theoretical studies, the advantages of laser etching and ECM were complementary on the object of typical polycrystalline silicon with optimization of process parameters and coordination the actions of the two processes. Then the ideal array optical traps have been machined on the surface of polycrystalline silicon solar cell with the new process. The correspondence between the reflectivity of the polycrystalline silicon surface and the geometric characteristics of array traps was established with morphology scanning and photoelectric detection. All of the research on this project will provide the theoretical guidance for the development of new efficient texturing technology on multicrystalline silicon solar cells.

太阳能的开发和利用已成为新能源研究领域的热点。针对光伏工业中多晶硅太阳电池光电转换效率偏低的问题，研究多晶硅太阳电池表面激光电化学复合阵列织构机理，以探索一种新型复合加工技术，改变传统的无序分布、重复一致性差的多晶硅绒面形貌加工，实现精密可控、有序密布的光陷阱结构加工，有效降低多晶硅太阳电池表面反射率。分别对液相环境下激光作用多晶硅表面微加工的成型规律、多晶硅受激光诱导生成自由载流子对电化学阳极氧化的影响以及激光辐射快速溶解钝化氧化膜对电化学作用的增强效应展开研究，揭示多晶硅表面激光电化学复合作用机理。在此理论研究基础上，以典型多晶硅材料为研究对象，优化工艺参数，协调激光与电化学作用，实现两种加工方法优势互补，完成多晶硅太阳电池表面阵列理想光陷阱结构加工，并通过形貌扫描和光电检测建立多晶硅表面阵列光陷阱几何特征与表面反射率之间的对应关系，为多晶硅太阳电池新型高效绒面技术的研发提供理论指导。

太阳能的开发和利用已成为新能源研究领域的热点。本项目针对光伏工业中多晶硅太阳电池光电转换效率偏低的问题，提出了一种激光电化学复合织构的多晶硅绒面新技术，改变传统的无序分布、重复一致性差的多晶硅绒面形貌加工，实现精密可控、有序密布的光陷阱结构加工。通过追踪光线反射过程结合物理光学罗曼几何法，总结了多晶硅表面光陷阱结构对减反射效果的影响规律，对阵列理想光陷阱结构进行了优化设计以满足高性能减反要求；通过对激光在静态和动态溶液中传输特性的研究，设计了两套多晶硅太阳电池激光电化学复合绒面试验系统并进行了对比实验，优选并优化了复合绒面试验系统以满足多晶硅激光电化学复合阵列织构的要求；基于温度场和电场理论，建立了多晶硅激光电化学复合加工理论模型，通过数值模拟与对比试验，揭示了以激光热力作用、多晶硅阳极电化学腐蚀作用和化学溶液的碱性腐蚀复合而成的多晶硅激光电化学复合阵列织构的材料去除作用过程；通过正交工艺试验，总结多晶硅太阳电池激光电化学复合阵列织构工艺规律，实现高质量绒面加工，有效降低表面反射率，激光电化学复合阵列织构技术制备的多晶硅表面对于波长400-760nm的可见光的反射率整体降低至10％以下，其中对于波长445nm以上的可见光的反射率降低至5％以下；通过表面形貌扫描和光学检测，建立了多晶硅表面阵列光陷阱结构几何特征与表面反射率之间的对应关系。本项目的研究揭示了多晶硅表面激光电化学复合作用的过程和机理，建立了理论模型，探索出了一种新型高效的多晶硅绒面制备技术。该技术有利于提高多晶硅太阳能电池光电转化效率，对于太阳能的开发和应用具有重要意义，也可以为半导体材料的激光电化学微尺度加工提供理论指导。