光伏晶硅Lamb波非接触缺陷检测传感器及成像系统研制

The silicon solar batteries, as green and environment-friendly energy resources, have already attracted extensive attention from all over the world. However, the various defects(e.g.,the cracks) of the silicon wafer will adversely affect the photoelectric conversion efficiency of the batteries. It means that how to quickly and effectively detect the defects with an in-situ non-contact method and improve manufacturing technologies to guarantee the quality of product is of great academic significance and engineering application value. The project proposes a new non-contact method to detect the defects of the silicon wafer by using Lamb waves, and also develop a novel non-contact Lamb waves transducer and imaging system for testing, including 1) to investigate Lamb waves propagation in the silicon wafer with a consideration of the effect of the silicon wafer's anisotropy, and mainly to research the displacement distribution of asymmetric modes and the conditions on generating the wave modes; 2) to optimally design and develop a gas-based piezoelectric composite line-focus transducer, to characterize the relationship between the physical size and resolution of the transducer, the structural style and acoustic impedance, the volume of components and acoustic impedance,the frequency and damping, other parameters and piezoelectric properties, etc., and mostly to focus on the matching of acoustic impedance and the improvement of manufacturing technologies; 3) to solve the acquiring of experiment data, signal processing and the construction of imaging system. And primarily to deal with high speed data acquisition, processing, imaging technology, etc. 4) to construct an integrated detecting and imaging system, and also to verify the detection of the defects in the silicon solar batteries.

硅太阳能电池作为绿色、环保的新能源受到全球广泛关注。然而，晶硅中的各类缺陷（如裂纹等）对电池的光电转换效率影响颇大。如何非接触快速有效地在线检测硅太阳能电池晶硅中的缺陷，进而改进制造工艺，确保产品质量，具有重要的学术意义及应用价值。项目提出一种Lamb波非接触检测晶硅缺陷的新方法；研制一套新型的非接触Lamb波传感器及检测成像系统，包括：1)研究Lamb波在晶硅中的传播特性，考虑晶硅（如单晶硅）的非各向同性对波传播的影响，重点研究低阶非对称模态的波结构及产生条件；2)优化设计、研制气体基压电复合材料线聚焦传感器，研究探头几何尺寸与分辨率、复合结构形式和材料体积组份与声阻抗、频率与衰减以及各参数与压电特性等关系，重点研究传感器的声阻抗匹配与制造工艺；3)研究数据采集、信号处理与成像软件系统。重点解决数据高速采集、处理、成像等关键技术；4)集成构建检测成像系统，并验证太阳能电池晶硅缺陷的检测。

晶硅是太阳能光伏领域中的重要原材料之一。在单晶硅及单晶硅太阳能电池片的生产和使用过程中，可能会产生各种类型的损伤，这将导致其光电转换效率的降低，进而影响正常的发电过程。空气耦合超声检测技术因具有非接触、检测方便等特点，被广泛地应用于材料的在线检测。本项目基于空气耦合超声检测技术，开展了光伏晶硅Lamb波非接触式缺陷检测方法研究，并研制了一系列气体基压电复合材料空耦传感器及成像检测系统。. 首先，研究了单晶硅中的导波频散理论和频散曲线计算方法，揭示了导波在传播过程中的频散特性；建立了空气耦合条件下激励/接收 Lamb 波的条件，研究了低阶模态 Lamb波的入射角与频率之间的关系，并分析了单晶硅材料的各向异性对 Lamb 波传播特性的影响；提出了单晶硅片中 Lamb 相速度和群速度的测量方法，分析了 Lamb 波与单晶硅片中不同深度、不同取向裂纹缺陷的相互作用机理，并提出了基于相关函数法的裂纹缺陷检测技术。其次，基于空气耦合超声检测技术，建立了气体基 1-3 型压电复合材料仿真模型，优化设计了传感器结构参数；研制了一系列基于气体基 1-3 型压电复合材料的空气耦合超声传感器，并进行了声阻抗匹配研究。再次，进行了单晶硅片中裂纹缺陷的成像技术研究及单晶硅太阳能电池片中裂纹缺陷的扫描检测技术研究；集成了空气耦合超声检测平台，研制了自动化空气耦合超声检测系统。最后，对影响空气耦合超声检测的因素进行了分析。