Pb-free front-contact silver pastes with SnO-P2O5 glass frit for crystalline silicon solar cells

摘要

We developed a new Pb-free Ag paste with a SnO-P2O5 glass frit for front contact electrodes of crystalline silicon solar cells. First, we synthesized SnO-P2O5 glass frits with various compositions, whose glass transition temperatures were 225-245 degrees C, by using a melt-quenching method. It was experimentally verified that the glass component SnO etched through the silicon nitride anti-reflection coating on the Si emitter. Then, four kinds of Ag pastes with various SnO-P2O5 glass frits were prepared, screen-printed on a Si emitter, and fired to fabricate solar cells. The composition of the SnO-P2O5 glass frit affected the surface and interfacial morphology and microstructure of sintered Ag grids, which played an important role in the series resistance and photovoltaic properties of the solar cells. It was worth noting that the cells fabricated with SnO-based Ag pastes revealed no glass layer at the interface between the Ag grids and Si emitter. This differed from cells fabricated with Ag pastes containing Pb- or Bi-based glass frits. The highest efficiency of 7.2% was achieved for cells fabricated with the Ag paste containing 67SnO-33P(2)O(5) (mol%) glass frit at a firing temperature of 950 degrees C and a time of 5 min. This was because this Ag paste possessed the densest structure and lowest interfacial contact resistance. (C) 2016 Elsevier B.V. All rights reserved.