Screen-Printable Silver Pastes with Nanosized Glass Frits for Silicon Solar Cells

Abstract

In this study, silver pastes containing different sizes of glass frits were employed to form the front-side electrodes in order to examine the size effect of the glass frits on the interfacial microstructures between the front-side silver contacts and the n-type silicon emitter layers, which will subsequently affect the electrical performance of silicon solar cells. The interfacial microstructures at the Ag/Si interfaces were investigated by advanced electron microscopy techniques. The transfer length method (TLM) was used to measure the specific contact resistivity of silver electrodes screen-printed on the n-type silicon substrates. The particle size of the glass frits was found to strongly affect the interfacial microstructures and therefore resulted in different specific contact resistivities (ρ c) of the fabricated silver ohmic contacts. Nanosized glass frits showed excellent etching ability during engineered thermal treatments. The samples made with silver pastes containing microsized glass frits showed a thick residual glass layer at the Ag/Si interface, while the silver paste with nanosized glass frits was found to form an interface with less glass residue, which led to lower resistance after otherwise identical processing.