| 초록 |
Silver paste has been commonly used to form contacts to the n+ emitter in Si solar cells. The glass frits in Ag paste etch the SiNx anti-reflective coating layer of Si wafer under fast firing. The size and distribution of the Ag recrystallites formed at interface Ag electrodes/Si wafer was studied as a factor affecting ohmic contact with n+ emitter. The purpose of this study is to understand the effect of basicity for the PbO-TeO2-SiO2 glasses on the interface between the Ag electrode and the Si wafer, and on the electrical characteristics of 4-busbar Si solar cells. Thermal properties of frits were measured by a differential thermal analysis and hot stage microscope. The interfaces of Ag electrodes/Si wafer were observed using a scanning electron microscope. As a result, Ag crystallites were distributed uniformly on the Si substrate. The basicity parameter of the glass composition is proportional to the efficiency of the Si solar cells. When the Na2O content is 4 mole% in glass frits, the Ag crystallites of optimal size were formed to increase the efficiency of Si solar cells. It seems that the glass structures have changed with the addition of oxides, and also the reactivity of glass affect a conductive path between the Si wafer and the Ag electrode. |
