Metallic glass: A new approach of solar cell electrode for high efficiency Si-solar cell

For the last few decades, lead-based(PbO-) glass-frits have been used in Ag electrode paste for screen printing metallization on Si-solar cell because of strong contact formation with a low cost. However, due to the electric insulation of oxide glass (OG), even though a great deal of effort has been made to improve the contact resistance between Ag grid and Si-emitter by adding nano-sized fillers, such as nano-Ag or ZnO, etc., there is a huge limitation which could not be easily overcome with an intrinsic electrical insulation property of OG. Therefore, we suggest that the total replacement of OG with metallic glass(MG), which is a conductive, is a new approach to overcome the limitation of electrical properties of Ag electrode paste. In this research, Al-based metallic glass(Al-MG) has been selected with the advantages of high oxidation resistance, low Tg (glass transition temperature) and high solubility in Ag. The contact resistance and specific resistivity of Ag/Al-MG electrode are achieved 0.5mΩcm² and 2.9 μΩcm, respectively, which are comparable to those of electroplating electrode. The performance of Ag/Al-MG electrode is also proved in i-BC (inter-digitated back contact) cell of which conversion efficiency showed above 20.3%. We will discuss about the mechanism of Al-MG electrode contact formations, including a wetting behavior of Al-MG and the reaction steps between Al-MG and Ag during the firing processing.