掺银碲基无铅纳米玻璃粉的制备及在正银电极的作用机制研究

With the increasing emphasis on human health, lead-free has become an inevitable trend in the development of electronic products. Glass frit is an important material for the preparation of silver front electrodes for crystalline silicon solar cells. Lead content of silver electrodes can be reduced and the photoelectric properties of the cell can be enhanced by silver paste based on tellurium-based glass frit. However, their application will be restricted since the mechanism of the lead-free tellurium-based glass frit at the silver-silicon interface is not clear and the performance of glass frit is not stable. Therefore, the development of high-performance lead-free glass frit has become challenges and opportunities for future solar cells. In this research proposal, based on the preparation of the lead-free silver-doped tellurium-based nano glass frit by sol-gel method, we aim to analyze the amorphization mechanism of nano glass frit, to construct “chemical-structure-performance” relationship model, to systematically study the mechanism of the lead-free silver-doped tellurium-based nano glass frit in the silver front electrodes, to elucidate the chemical bonding, ohmic contact effect and current transmission principle of silver-silicon interface, to reveal the effects of composition, microstructure and morphology of glass frit on photovoltaic performances of solar cells, and then to realize effective regulation on the thermal and electrical properties of lead-free silver-doped tellurium-based nano glass frit. Ultimately, we hope to put forward the development of lead-free tellurium-based nano glass frit with high-performance.

随着人类对身体健康的日益重视，无铅化已成为了电子产品发展的必然趋势。玻璃粉是制备晶硅太阳能电池正银电极的重要材料，基于碲基玻璃粉的电极银浆能够显著降低银电极的含铅量而提高电池的光电性能。然而，由于碲基无铅玻璃粉在银硅界面的作用机制不明确、性能不稳定而制约其应用前景。因此，开发高性能无铅玻璃粉成为了新的挑战和机遇。本项目旨在运用溶胶-凝胶法制备掺银碲基无铅纳米玻璃粉，分析纳米玻璃粉的非晶化机理，建立玻璃粉的“组分-结构-性能”关系模型。系统研究掺银碲基无铅纳米玻璃粉在太阳能电池正银电极界面的作用机制，阐明银硅界面的化学键合作用、欧姆接触效应、电流传输原理等，揭示玻璃粉的组分、微结构、形貌对太阳能电池光电性能的影响规律，从而实现掺银碲基无铅纳米玻璃粉热学、电学性能的有效调控。在此基础上开发高性能、无铅的碲基纳米玻璃粉。

太阳能电池正面电极银浆主要由银粉、玻璃粉、有机载体和添加剂组成，其中玻璃粉占比4~5 wt%。尽管玻璃粉含量不高，但是它在正银电极中发挥重要作用：它既是氮化硅减反射膜的腐蚀剂和金属银的传输载体，也决定着正银电极的附着力和电池的可靠性。但是目前用于正面银浆的玻璃粉以铅基玻璃粉为主，随着人类对身体健康的重视，无铅化成为了晶硅太阳能电池的必然趋势。本项目提出运用溶胶凝胶法制备掺银碲基无铅纳米玻璃粉：（1）以硝酸铋、硼酸、正硅酸乙酯、碲酸、银铵为前驱体，运用溶胶凝胶法制备TeO2-Bi2O3-SiO2-B2O3纳米玻璃粉和掺银TeO2-Bi2O3-SiO2-B2O3纳米玻璃粉，两者均为微晶玻璃粉，纳米玻璃粉尺寸为200~300nm，玻璃转变温度分别为343度和356度；（2）以银氨溶液为银源，淀粉同时为络合剂和还原剂，通过“一锅法”制备了纳米银@铅基玻璃粉复合粉体。玻璃粉表面银纳米颗粒粒径为20-30nm，其熔点比块状银的熔点低约200度；（3）通过研究基于银粉振实密度以及不同种类玻璃粉对银电极表面形貌和电池性能的影响，可以得出基于86%混合银粉，4%纳米银@玻璃粉，10%有机载体的电极银浆所制的太阳能电池光电转换效率最高，达到18.54%；纳米玻璃粉与铅基玻璃粉的性能基本相当。