Contact resistance measurement techniques for Ag thick-film screen-printed contacts to solar cells

The contact resistance of Ag screen-printed contacts to solar cells has been studied by the implementation of three different contact resistance measurements techniques. It was found that Transfer Length Method (TLM) is not appropriate for evaluating screen-printed contacts to solar cells while a new technique using a special pattern consisting of squares is better suited for this kind of metallization. It is also suggested the existence of an edge effect, making the contact resistance inversely proportional to the contact periphery instead of the presumed inversely-proportional to the contact area behavior. Various contact resistance measurements - on samples with several firing conditions - and scanning electron microscope images seem to validate what previously stated.