Development of an electrically highly conductive adhesive with a low silver content for the production of solar modules

Due to man-made climate change, energy generation from renewable sources has become increasingly important in recent years. In addition to wind energy, biomass, geothermal energy and hydropower, renewable energies also include photovoltaics. The majority of solar cells used are silicon solar cells. These are mainly connected electrically and mechanically by soldering to form solar modules. Due to the high temperatures and the different expansion coefficients of solder and silicon, the solar cell is exposed to high thermomechanical stress. Soldering is therefore not suitable for some applications, such as the connection of thin-film solar cells.

Electrically conductive adhesives can be used as an alternative for connecting solar cells. The electrical conductivity is ensured by silver particles dispersed in the adhesive. The silver content of the adhesives currently used is usually over 50 % by weight. The aim of this research project is to use an innovative paste concept to significantly reduce silver consumption without impairing electrical conductivity and adhesion strength. To this end, pastes are produced according to the concept of capillary suspensions, so that conductive network structures are formed at a significantly lower particle volume fraction than is the case with suspensions in which the attractive particle interactions are primarily based on Van der Waals forces. In addition, the flow properties of the paste are to be optimized for screen printing so that the new adhesive can be integrated into existing manufacturing processes. The aim of the project is to further reduce resource consumption and costs for the production of solar cells in order to promote the use of photovoltaics for the generation of electrical energy.