DEVELOPMENT OF ADVANCED SCREEN-PRINTED AND FIRE-THROUGH METALLIZATION FOR POLYSILICON BASED PASSIVATED CONTACT SOLAR CELLS

Abstract

This thesis focuses on the screen-printed metallization of the doped polysilicon layers used in a passivating contact solar cell. Screen-printed metallization with fire-through (FT) pastes is an important enabler of the commercial success of the polysilicon based passivated contact solar cells. This thesis presents an in-depth analysis of the characteristics of the contacts formed with the FT pastes to the doped poly-Si layers. Contacts to n+ poly-Si are formed with FT Ag pastes while those to p+ poly-Si were formed with FT Ag-Al pastes. The properties of the contacts were analyzed for different physical conditions such as metal pastes, firing temperature, thickness of poly-Si and surface morphology. The contacts were analyzed by measuring the contact resistivity and modeling the recombination characteristics. The observed characteristics are further investigated by analyzing the SEM images. Large area n-type monoPolyTM solar cells prepared using the appropriate pastes resulted in 23% efficiency, while a pathway for efficiencies approaching 26% is presented.