Inert drying system for copper paste application in PV

In this study we show that the electrical characteristics of low temperature polymer pastes are improved by carrying out the curing process in an inert nitrogen atmosphere. In order to reduce the solar cell production costs, numerous scientific works are devoted to the question, whether the commonly used silver paste can be replaced by a copper based paste. However, a major problem with the latter is, that copper tends to oxidate during the thermal treatment. Hence, this work focuses on the development of an inert inline drying system to avoid the oxidation of copper based polymer pastes. For reference, silver based polymer pastes are investigated simultaneously. Therefore the influence of different nitrogen curing atmospheres on the electrical resistance and the weight loss of the pastes is evaluated. The electrical resistance of both silver and copper based pastes is improved by reducing the residual oxygen concentration. To investigate the reason for this, the samples are analyzed by micrographics. Furthermore it is shown, that the weight loss of the pastes shows no dependence on the curing atmosphere.